#55 Food for Thought: Unpacking Nutritional Science

Dr. Carol Loffelmann, Assistant Professor, University of Toronto


February 27, 2019

What's the science behind the new and improved Canada Food Guide? Is the hype surrounding the keto diet and intermittent fasting supported by evidence? Can your genetic code tell you what diet is best for you? In this installment of Raw Talk, you'll find out! Dr. Carol Loffelmann shares how she leveraged her scientific and medical expertise as an anesthesiologist and Assistant Professor at U of T on her journey to becoming an advocate for evidence-based nutritional guidelines and the health benefits of a low-carb, high-fat diet. Expanding on this, you'll hear about the glycemic index from the man who created it, Dr. David Jenkins, a Scientist at Li Ka Shing Knowledge Institute. Dr. Hoon-Ki Sung, Scientist at Sick Kids Hospital, also takes us through how intermittent fasting actually works and what happens in our fat cells. To learn about the future of food, we spoke with Dr. Daiva Nielsen, Assistant Professor at McGill University, about nutrigenomics and how genetic variation affects individuals' response to diet. Finally, we chowed down on the Beyond Meat Burger, made with 100% plant-based protein, with MD/PhD candidate Amy Khan. Your hunger for nutritional knowledge will be satisfied after this one!

Written by: James Saravanamuttu

Canada Food Guide
Food Guides From Around the World
Canadian Clinicians for Therapeutic Nutrition
Dr. Jenkins' Top 10 Healthiest Foods
Science of the Impossible Burger
MacLean's Less Meat, More Choice
Ultimate Veggie Burger Taste Test

Mashup Clip 1 [0:03] Health Canada is updating a decade old Food Guide. Canada's new food guide-. Long awaited update to Canada's Food Guide-. I mean, what would happen if I ate nothing but McDonald's for 30 days straight? It's the diet you've all been waiting for-. Hey, so you're interested in starting intermittent fasting-. The keto diet, it sounds like the magic formula. The environmental impacts of the food system are daunting, it's responsible for a quarter of our green house gas emissions. What we're going to try today are the first thin slices of steak we have produced in a lab setting.

Grace Jacobs [0:38] Is it just us? Or do you find yourself overwhelmed with all the information out there about what, when, and how much you should be eating? We all know that we should eat a healthy, balanced diet. But what does that really mean in practice, it's definitely not as easily done, as it is said. When you're stressed or have a lot of work to do, or just tired, it's much easier to just simply pick up something or order in. On the other end of the spectrum, there seem to be an increasing number of people who are taking their nutrition to the other extreme, with strict diets to cut out all sugar or involve fasting. Today we're gonna explore different aspects of nutrition and diet, including common misinformation, and evolving recommendations for a general healthy diet released in Canada's new food guide just last month. We're also going to talk about some of those interesting diets that we seem to be hearing more and more about, like the keto diet or intermittent fasting. Finally, where's the future of food going? As we continue to learn more. Have you heard of meatless meat or nutrigenomics? Don't worry, we've got you covered. Hi, listeners. I'm Grace, and welcome to raw talk podcast's 55th episode.

Grace Jacobs [1:49] We first wanted to learn a bit more about Canada's new food guide and what this means for health for Canadians. So I spoke with Dr. Carol Loffelmann, a co founder of the Canadian clinicians for therapeutic nutrition. This group advocates for evidence based dietary guidelines and education, and did a lot of work to try and make sure that the development of our recent Food Guide followed and reflects this approach. Carol hasn't always been an advocate for nutrition though, and is also an anesthesiologist at St. Michael's Hospital here in Toronto.

Dr. Carol Loffelmann [2:15] I myself grew up in the 80s, in school where we learned the Canada Food Guide. I went to medical school in the 90s, where we learned the Canada Food Guide. I tried to apply the Canada Food Guide to my own life and health, and there was a point where I was trying to ship some baby weight and the baby was four years old. So it didn't really qualify anymore. But I went to the medical literature and I read the most recent reviews, and what should be done. Indeed it said you should eat less and move more. So I tried to doing that. I did a lot of extra exercise, and I did further cut down fats as they said that I was supposed to do. Instead of losing weight, I put on weight. I had a lot of hunger at the same time because exercise makes you hungry, you work up an appetite. I was talking to one of my other anaesthesia colleagues explaining the challenges that I was facing, and she said, "oh, you should try the Paleo diet." I knew that that was something that she was doing, and I thought, "oh, yeah, sure, that goes against everything". All that saturated fat, that's going to be bad for me, there's no way that I can do that. So the Paleo Diet is a way of eating that mostly removes the processed foods from one's diet. In doing so, you end up eating more fat to make up the caloric difference, because if you focus on whole foods, that's what's present. You've got the same kind of amount of protein that you're eating, there's more fat and less ultra processed carbohydrates. So it looks on paper as if you're doing the wrong thing, if you believe the paradigm that we grew up in the 80s 90s and early 2000s. The other thing that the Paleo people do is that they try to recreate the kind of foods that you would have eaten in the Paleolithic time. So they also don't eat dairy. But I wasn't about to give up dairy. So I started to look at what well what's the science underlying it because I saw enough people being able to apply those kinds of that structure to the way that they eat, to get benefit. They leave the Western diet pattern and they move to something that is less processed and they begin to find improved nutritional health, body health, sleeping, decrease acne, decreased signs of PCOS (Polycystic Ovary Syndrome). There's a bunch of things that people were saying we're getting better and so I went to see if there any science behind this and lo and behold, there have been researchers all along saying, "wait a minute, don't drop the fat in your diet, but do drop the ultra process and the easily absorbable sugars that contribute to your diet and see what happens." So then I followed what happens next? If you do that, if you put less on your plate, less in your mouth, less gets to your gut, what happens at the next step? Well, as it turns out, your hormones change in their response to the food that you eat. So instead of making this a willpower focused, eat less, move more, you reframe, and retrain your body to express the normal hormonal responses, that we probably, through wisdom, figured out which foods were good for us, that we abandoned in a large part since the 70s, when they told us to eat low fat. Low fat really doesn't taste good. Low fat requires additives in order for it to be palatable. Unfortunately, those additives tend to trigger one to eat more, or leave you only full for a shorter period of time. Many people have an experience of "hanger". Hanger is the 2.5 hour feeling that you get when your professor is talking for a little bit longer than maybe you had anticipated, and the cereal and skim milk that you had for breakfast is sort of passed into your system, and been partitioned, because that's what your body's supposed to do. But now you're left, because of your internal hormones, with sort of this energy deficit and you get a clear message saying, "you better find something else to eat more quickly." You don't get that if you're eating a nutritious, satiating and satisfying first meal of the day. You really change what hormones come into play at the next meal. It's interesting where that came from, that came from messages for people who were using insulin to manage their type one diabetes. If your insulin only lasted certain amount of time, then you needed to eat again. Otherwise, you were actually at risk of having a mismatch between your energy availability and insulin activity. So we changed a very specific instruction for a small subset of the population and moved it to a global message. That's what I'm afraid that we're doing currently with the global message.

Grace Jacobs [7:26] Carol's discuss the health benefits of cutting out processed foods and focusing on eating a high fat, low carb diet. Which is the opposite of what we're often told. What's really happening in our bodies when we intake carbohydrate, though? One of the most important hormones in our metabolism is insulin.

Dr. Carol Loffelmann [7:41] Yes, so we're gonna move into a hormone centric way of looking at the way that your body mass is distributed. The master hormone and all of this is insulin. Insulin goes up in response to your carbohydrate load primarily, a little bit too protein, very little to fat. What you want, mostly from all of your hormones across your body, is a spike in response to stimulus, and then a fall. I've just put my finger in the air for the listeners, and I've put it back down again. If you can imagine that that would happen, each time that you eat, you want your insulin level to fall again, because insulin is a fat storage hormone. Everybody knows the effect of insulin on sugar, that's to stuff sugar into cells so that you don't have too much glucose in your blood system, but that's not its only effect. It has multiple effects at different levels along the y axis of my finger going up and down. So what happens over time is, if you are insulin sensitive and you eat a meal that your body can respond to the load of carbohydrate that's in there, your insulin will spike and your insulin will come down. It's the point at where it comes down, that stops storing fat and actually allows the lipases in your fat cells to let go of the stored energy so that you can convert now back to burning fat. Most people's metabolic rate is completely covered by aerobic processes, which run on fat through your mitochondria. It's not a glycolytic life that we're leading as humans, unless you're sprinting and you can only do that for a very short amount of time. What happens though, is if your next feed, if you think about that falling insulin level, if your next feed comes too quickly, you eat a doughnut at the first meeting of the day, your insulin has to respond again. So your pancreas has to sense the sugars coming by let the insulin out to, again, decrease the amount of sugars in your bloodstream. The amount of sugar is in your bloodstream is a thing that we're trying to keep in a very tight homeostatic amount, area, or numbers. If you never got to the point of where your insulin fell, then you've just stored and stored. So you've got two storage episodes with your two feeding episodes and have never released. If that happens,again, if that happens again, and if that happens again, now your baseline insulin never gets to the point of decreasing enough to allow the lipases in your adipocytes to release your other alternative fuel, your resting fuel. Now you're running on the fuel that is supposed to help you run, specifically. When that goes through your mitochondria, you actually make more reactive oxygen species, not so good for inflammation, it says at the cell level to become insulin resistant. So like "we have lots of fuel in this cell, now, you can save it for something else, we don't want it here." As that happens to each of the different tissues, and that will happen at different amounts, and again different levels on the y axis of of insulin, you end up having this storage only and a resistant response at the cellular level. So if you keep doing this over, and over, and over again, and it's easy to do in the western food environment, if you have a low fat cereal, with some low fat, milk and some juice... thankfully, juices out of the Canada Food Guide now, so hopefully, nobody's having juice. But if you walk down the street, there are lots of juice places that are open commercially, that don't look empty when I walked by them. So people are still drinking this, we can say one thing but people's behavior, and what drives that behavior is pretty interesting. But people's behavior is different... If over time you keep your insulin level high, you have hyperinsulinemia, your insulin resistance is high, you need more released over time, and more tissues become insulin resistant. So when you look now at research, there's insulin resistance of the brain, insulin resistance of the bone, of the synovium, of the kidney, the liver, of the fat cells. Then what do those fat cells do? They get overstuffed, they start secreting their own cytokines, they start changing the chatter between your fat and your muscles. Muscles have their own signaling molecules myokines, and you change the way that your body runs, and you change it away from a fat burning mode. So you're now you're reliant on sugar, that changes your behavior. You can't access it, you become hungry, you eat what's available, walk down the street, you're going to have that same stimulus again. So the Western food environment seems to be the vector of these diseases. Because insulin receptors are on all those different tissues, they all display abnormal phenotypes. Which one you display as an outside disease depends on you. So there are some women who in their teens will already have polycystic ovarian syndrome, and that is related to hyperinsulinemia. We have cystic acne, hidradenitis suppurativa, that's another skin condition affects both men and women. These are not diseases of old age, which used to be called sugar, diabetes, your great grandparents they would build up over time. So their insulin spikes kept going, their tissue insulin resistance, which does seem to increase as you age, would start to add up, and you would see people develop these diseases in their 60s and 70s. We have teenagers with type two diabetes.

Grace Jacobs [14:13] To learn more about the changing hormone levels and our body's response to carbohydrates, James sat down with Dr. David Jenkins, who created the glycemic index. He's a university professor at U of T and a physician scientist at St. Michael's Hospital in the realm of nutritional sciences. His research focuses on the relationship between food and diabetes and cardiovascular diseases.

James Saravanamuttu [14:33] Could you tell us what exactly is the glycemic index?

Dr. David Jenkins [14:35] Well, it's simply looking at the degree to which the blood glucose rises after a meal rises and falls after a meal. In other words, the hump in blood glucose that you get after a meal, do different foods produce different humps? Does all carbohydrate produce the same hump and if so, if they are different, can you standardize it? So all we did was standardize the postprandial rise and fall in blood glucose over a two hour period for normals, and a three hour period for diabetics. We standardized against, initially glucose, but that was really not very palatable. So I've preferred to have a standard white bread, which gives a pretty similar blood glucose response always on the glucose scale, white bread is usually 71. So if you adjust the white bread to 100, then all the foods become either above white bread, or below white bread. It's also not only easier to test in observation... you have to test these glycemic indices in groups of human beings, and others groups of people look at the test, and then they take the test and take the control, and we look at the the test food over the standard foods and that was glucose, so white bread, and multiply that by 100. So just the percentage rise that one gets against the standard, because most people don't drink glucose, and never come across it in their diet. So it's sort of almost an irrelevance. It's good for academics, but not very good for practical instruction of patients. Nobody's going to remember the glycemic indices of different foods. That's why I think, ones taken this more academic topic, and tried to make it more easily accessible to ordinary people. So that if I say to you that in general, beans, peas, lentils, legumes, pulses, have a low glycemic index that's good enough for you. You can then realize that you could have a lentil stew, or soup, or chickpeas or hummus, and you would probably be getting low glycemic index food, they're not going to raise your blood glucose that much. If I say to you, and I say it advisedly, that if you take processed foods, and if you take processed breakfast cereals, which don't have much fiber in them, then you will get a very high rise in blood glucose. If you take something like potatoes or rice, on average, they will be just about the same as bread perhaps a little bit lower for some. For the glutinous rice that you get in your Chinese restaurant, you can pick up in your chopsticks because that's a little more hydrated, that actually gives a bigger rise in blood glucose because digestive juices can get to it and attack it more readily. Fruit, especially temperate climate fruits, apples, oranges, and these sort of things tend to be lower glycemic index. So fruit, vegetables, beans, peas, lentils, things like pumpernickel bread, the German type, heavy rye bread with whole grains in them, they tend to be digested more slowly, and they give a flatter blood glucose rise. Interestingly so does pasta by comparison with bread. So pasta is tends to be lower than bread...

James Saravanamuttu [18:06] ...regardless of say whole grain or white?

Dr. David Jenkins [18:09] ...regardless of white or brown. In fact, white or brown in terms of bread doesn't make much difference. The brown is obviously one thinks is better, because it's got more minerals, it's got more protein in it. So I mean, I would always advocate brown irrespective of glycemic index. But pasta is interesting, and pasta is probably a very good food. The problem with pasta is, it's very difficult to restrict. In other words, if you see a serving of pasta on a plate, you'll be sad. You tell someone, "that's just too little." No one needs a serving of pastor, so you eat two, or three, or four servings of pasta in one go. That's where pasta got the bad name. It's not because it's a bad food. It's a good food, but it's it's just too tasty.

James Saravanamuttu [18:53] Right now, you mentioned the benefits of legumes earlier, and just context in this room where there's quite a bit of cans of...

Dr. David Jenkins [19:01] ...cans of peas. Well we try and make sure that patients, when they go away, they take some with them. Just to to educate them basically, go and take them, go and try them. Because many people have never eaten beans, peas, and lentils. They think that's just prison food.

Grace Jacobs [19:17] As we mentioned, a new version of Canada's Food Guide was just released this January to replace the previous 2007 one. This version is a lot simpler with a single plate with many different images of food types within the three categories. Recommendations are that half of your diet is vegetables and fruits, a quarter protein, and a quarter whole foods. They've done away with specific serving sizes, having dairy as its own food group, and recommend a reduced meat intake. There's also a part of the guide on healthy food habits that encourage cooking at home, being mindful of what you eat, and eating with others as often as you can. There's a clear consensus that it is a step forward in providing more accurate and healthy informations to Canadians. There's been a lot of praise that the guide is less industry influenced. We asked our guests what they did and didn't like about the new guide.

Dr. Carol Loffelmann [20:01] So I do think there are several areas that they got very right. One is Canadians need to learn how to cook, we have lost generations of people to easily prepared meals, which are often food based, not whole food based. So if more Canadians knew how to prepare a simple, nutritious, nutrient dense meal that would go a long way already in reclaiming the kind of diet that sustained us for millennia. I think that the caution against sugars and severe limitation of sugars, especially to young Canadians, is a big step forward. When we were there at Health Canada, they said, "Well, we did the same scientific review and ended up with low sugars. So you like that, right?" And we said, "Yes, we do like that. You don't need to change it." But we think a full scientific review would have also found that so we don't want them to change that, that's for sure. I think that getting rid of juice is a great idea. Getting rid of sugar sweetened beverages is a great idea. Getting rid of chocolate milk from schools is a great idea. We have reversal of that decision in one of the maritime provinces recently, which was a big disappointment. That was a political decision, but it's not a decision for health. So much better is to substitute all those drinks with water, and if you're going to include dairy in your diet, whole fat milk, not skim milk.

Grace Jacobs [21:56] With the release of the previous 2007 Food Guide, there was also an indigenous specific food guide released for First Nations, Inuit and Metis. The main differences between these were the presence of more traditional meats and foods, such as bannock. The new food guide is considered a step forward because it acknowledges the social, cultural and historical factors that can affect Indigenous people. It includes an emphasis on including culture and food traditions, and the recommendations for healthy eating habits. There is also talk of plans to create more distinct Food Guide versions that are resource specific to geographic region, as well as translated into local indigenous languages. However, there's pushback that the plate of food doesn't represent frozen alternatives for Canadians that don't have access to fresh options, or examples of the culturally diverse food that is eaten across Canada. Carol talks about the importance of this and acknowledging that Canadians come from diverse backgrounds. Also, if you want to hear more about Indigenous perspectives on health in general, take a listen to our recent episode number 53.

Dr. Carol Loffelmann [22:54] We think that their messaging on traditional foods for the Indigenous population is excellent. I think that in addition to the last ability to cook those foods, the last cultural aspects that came along with that the procurement of the foods, the sharing of the foods, I think that a move back towards that would be great. But each Canadian comes from their own cultural heritage of way of eating. That I think if you went back and looked at what made your great grandparents healthy, if you were to adopt something like that in the Canadian context, then you'd probably find yourself either staying nutritionally healthy or moving back towards health. Eating with others, being social, is a really good thing. So they have chosen a single dietary pattern of eating and are trying to apply it to the whole population. While we have evidence that the current population approaching 88% of us already can't tolerate the amount of carbohydrate that's on that plate. We think that their messaging with their pictures at least, around their whole grain category actually has a large number of refined grains within it. People aren't eating wheat berry salad, they are eating what they think is whole wheat pasta, which is still a highly refrain, refined grain product. And even some of those fruits that are there. If you're metabolically unwell, it's going to be too much for you based on that insulin centric hypothesis.

Grace Jacobs [24:40] We now turn back to Dr. Jenkins for his thoughts on our new food guide. Dr. Jenkins has long been active in advocating for a healthier diet for Canadians by formulating nutritional guidelines for the treatment of diabetes, as well as the food industry by working with loblaws and the development of their blue menu products.

Dr. David Jenkins [24:55] I think what they've emphasized is plant foods fruit vegetables, they've also really made a push not to have too much refined carbohydrate foods, which tend to be higher glycemic index. So they've they've cut those down a little bit, they've suggested eating more plant protein foods, which tend to reduce the postprandial blood glucose response to a meal. So in a way, what they've done is they've been a little bit more specific than previous guides, in making $1, more low glycemic index than one would have gotten normally. I think what they've done too is they've done a responsible thing in really emphasizing the plant food component of your Dart, which is new. They've had a certain amount of flack, obviously, from the Canadian Beef Council, and the dairy farmers. They've obviously objected to the fact that they've been, as it were downgraded in terms of importance. But I do think that was not an unexpected move. It's happening internationally, and Canada is simply going along with what is the science internationally, it's not sticking its head in the sand as it were, and still doing what it was always doing. But always when there's change, some people get distressed, and one one feels sympathetic for the people whose jobs may be in jeopardy. I think that that they went as far as you can go. I think one can only do these things incrementally. I think they probably thought that making their first statement, you should eat more fresh fruits, vegetables, whole grains, cereals, legumes, and concentrate on plant proteins. That was a big departure from the previous and I think so it's, I just hope, and they do have one sentence, which I would like to have been two or three sentences, they have one sentence talking about mentioning the word environment, actually in the in the Food Guide. And I think that's important, because I think other nations have been doing that. And I think Canada will have to step up. And this is one of the one of the concerns that for example, the beef industry may be responsible for 14% of greenhouse gas. It's one of the major agricultural contributors to greenhouse gas emissions. So again, these things have to be understood.

Grace Jacobs [27:29] The release of the new food guide comes at a critical time as chronic diseases such as type two diabetes, and cardiovascular disease, that can be prevented or greatly reduced by proper diet, become more and more prevalent.

Dr. Carol Loffelmann [27:41] Right now, 57% of the calories of teenagers in Canada, come from ultra processed foods. So if you eliminate those foods, and they did this in a randomized control trial, and in teenagers who had fat signs of fatty liver disease. If you get rid of the ultra processed, not even go very low carb... they still let them eat things like bagels, but they didn't let them have pop... you can see reversal of these conditions. So what's great is that your underlying evolutionary heritage, what you have gotten from your great grandparents is just waiting to have the right nutritional signals presented to you and then you can respond, it can't all be as simple as that. People are also looking at the microbiome changes that happen. They're discovering new communications between your gut and your brain, to between the neurotransmitters that are made from your gut and end up affecting your behavior in your brain.

Grace Jacobs [28:46] It's exciting that negative consequences from poor diets can be reversed with a change in behavior and food choices. Carol told us more about her experience with how high fat low carb diets can be helpful for improving health, and how her advocacy work with Canadian clinicians for therapeutic nutrition is making an impact.

Dr. Carol Loffelmann [29:05] I do see enough times and enough evidence that this sort of approach can be a therapeutic, very powerful tool for people. Canadians are doing it right now with or without their physicians. So, as part of my outreach, I guess my advocacy is to create capacity within the Canadian healthcare providers. As such, we created Canadian clinicians for therapeutic nutrition, providing a space for people to really question our training, question the current paradigm and see, "why are my patients getting better not following what I learned?" Everyone remembers back to their first week in medical school where they say 50% of what you learn is incorrect in medicine. If you only knew which 50 percent that was, well, this is a big part of the 50%. If we can do a course correction, if we can put people on a different path, and say it's okay to try this, I will follow you as you do this, that's very empowering for patients. As I said, there's a large movement out there, people who are doing it, and they want physicians to be there and supportive of them in trying this. So we're supporting each other in trying to look critically at the science and apply or teach our colleagues about this new sort of insulin centric model, hormone centric model, get away from the eat less move more model, and see why it didn't work and see what are the limitations of this as well. There are some people who can remain insulin sensitive, and they don't get that insulin resistance, no matter what they eat, we all know those kind of people. Even those people as they age sometimes can get thin on the outside fat on the inside cytokine storm from their belly fat and that sort of thing. Anyway, it's not for everybody, there's estimated 12% of the people who don't need this.

Grace Jacobs [31:10] So what was the process like to create the new food guide, or decisions about what was considered healthy, informed by scientific evidence?

Dr. Carol Loffelmann [31:17] We tried to impress upon Health Canada and the MPP, or sorry, MPs that if you do good science, you'll get good policy. Good science means looking at studies. We compared that to what they did, and that was to read reports. They read reports about the Dietary Guidelines for Americans, and they compared Canada's message and their message. If it matched, they declared that strong evidence. But that's not going back to primary studies, then they did the same thing for the World Health Organization. What we think a better way would be to do a large systematic review, using the accepted ways of studying other studies, rather than the reports of other other groups. We want that to be done by people who have very little skin in the game. So it will be best to have people who were trained in epidemiology, but really hadn't done any nutrition work up until this point, because we think that there are some possible biases that can change the questions you ask. So when we look at their scientific approach, it would be considered non standard. We just ask that it would be more standard and more rigorous. It's like this because this is how we have always done it. I think there are some influential people who didn't have any problem with the last round, because it worked for them. It worked for their blood marker of interest, that you can change someone's LDL, LDL C, which is a calculated value in Canada, that's a lipid protein that carries cholesterol around your body and changes a lot with diet. So we have had a focus on that, and even our current one that's the only biomarker that's mentioned in the Food Guide. Those other hormones changes that I talked about is not mentioned. The probably stronger markers like triglycerides, and HDL, the good cholesterol, they show better improvements with the kind of diet that I've just been talking about as well.

Grace Jacobs [33:59] Carol expanded more on why perhaps the process that Health Canada used wasn't as thoroughly scientific as we would hope.

Dr. Carol Loffelmann [34:06] Why we might end up with the food guide that we have? So I think rather than a scientific document, this is a political document. I think that Health Canada, while well intentioned, did not have the people power, the time, and the finances to do a proper scientific review. So it's understandable that they would go and look to other countries to try and save on... find some economies there. But those other guidelines were deemed unscientific because they didn't do a proper review either. So I think that we're in this bit of a catch 22.

Grace Jacobs [34:48] Although there were still some shortcomings with the guide and the process to create it. It is overall a huge improvement that will hopefully positively impact Canadians. So we've talked about a healthy diet in general and the higher fat diet, paleo. But another trendy diet we're sure you've heard of is the keto diet. This is also a low carb high fat diet, but with much more of an emphasis on the high fat portion, with it making up 60 to 80% of your intake. This approach is meant to promote ketosis a state in which the body burns fat for energy instead of relying on sugars from carbohydrates. While keto seems to be all the rage, with proponents claiming everything from increased weight loss to a better overall health, is there any science to back up the ketogenic diet? Well, it turns out the keto was actually used in a medical context to help patients manage certain conditions including diabetes and epilepsy. Patients with epilepsy for example, both high and low blood sugar levels can trigger a seizure. Ketogenic diets promote more protein intake, which in turn helps to stabilize blood sugar levels in children and adults who did not respond to seizure medications. A low carb, high fat, ketogenic diet has been shown to actually help reduce seizures. Keto diets are being recommended for patients with diabetes as a way to help improve their glycemic control. Dr. Carroll often spoke in depth about the insulin response system, which also benefits from the keto diet. Max sat down with Dr. Hoon-Ki Sung, who received his MD and PhD in South Korea before hopping over the pond. In 2014, Dr. Song established his own lab and studies adipose and metabolic biology at the translational medicine program at SickKids Research Institute. Recently, Dr. Hoon-Ki has taken an interest in intermittent fasting and published a paper in cell research that has gained international attention for its mechanistic look into fat changes resulting from intermittent fasting.

Dr. Hoon-Ki Sung [36:31] For me, I am doing 16:8, meaning that I'm not eating for 16 hours. But my own eating is happening within eight hours. If you search the internet about intermittent fasting, there are a lot of different type of intermittent fasting, like 5:2 IF (intermittent fasting) or 16:8, or five days per month. Evolutionary human beings and human fat is most one of the most important organ to survive during this ice age or, you know, food scarcity. Especially we are very interested in the hibernating animals. The fat tissue is very important because they can store a lot of energy in the fat, white adipose tissue. But human being these days, we don't use the stored energy at all because we always eat something. So we have sufficient or more than sufficient and that's why our fat uses only one function of our fat... we use only one function, the storage function. We never ever use the stored energy from the fat. White adipose tissue is like a regular fat we can think about. Brown adipose tissue maybe some people don't know about this one because in human and adult human, we believe that brown adipose tissue does not exist anymore. Brown adipose tissue is a heat producing organ. During our perinatal period, brown adipose tissue is very important to maintain our body temperature. But in adults it was questionable whether we still have brown adipose tissue or not. Recently, it was discovered that brown adipose tissue still exists in our adult body, and it is activated by cold or exercise. Whether it is related with the fasting or not, it's not known yet. So brown adipose tissue is heat producing fat tissue to cope with cold weather, while white adipose tissue is just an energy storage organ. Obviously, intermittent fasting has profound impacts everywhere in our body. But what we found is in white fat, color change was dramatic even with one day of fasting. That makes sense because during the fasting time, we should use the energy from the fat tissue. So that's why dramatic change has been happening in white adipose tissue and that's why we just focus on white adipose tissue. What is going to happen there?

Max Strauss [39:44] Was it conversion of white to brown tissue? Or transformation of white?

Dr. Hoon-Ki Sung [39:48] Yeah, actually that is still not very clear whether we are stimulating a stem cell to differentiate into brown like cell in white adipose tissue, or we are transforming white fat into brown like fat. So here I'm saying brown like fat, because this brown like fat is different from brown fat. They are in white adipose tissue, but they look like brown fat. That's why we call them beige fat. When we did an isochoric study... because, there is another type of diet program like calorie restriction... but our aim is, without calorie restriction, whether it's just the eating pattern change, within couple of hours can it have a calorie restriction like benefit or not? So when we did an animal study, we fast animal for one day, but the other two days they're eating whatever they want. So actually, then they compensate eating the amount of food for two days, then it was almost the same amount of three days of free feeding animals for the intake amount. So that's why without any calorie restriction, we have some metabolic benefits.

Grace Jacobs [41:24] Additionally, a recent paper published in Cell Metabolism looked at the relationship between fasting and the circadian rhythm, our body's natural clock.

Dr. Hoon-Ki Sung [41:32] They actually specifically tested whether circadian rhythm dependent fasting is better or not. The paper actually says that it is totally circadian rhythm independent, but fasting dependent benefit is existing. So meaning that maybe regardless of circadian rhythm, maybe fasting itself is actually getting some benefit, or fasting itself is actually dominating or overriding the circadian rhythm.

Grace Jacobs [42:07] Dr. Sung also talked about some limitations or adverse effects of intermittent fasting, things often not highlighted in the majority of internet literature.

Dr. Hoon-Ki Sung [42:16] We also observed some sort of adverse effects of intermittent fasting, for example, what if we stop? We found that there is a yo-yp phenomenon. If you stop intermittent fasting, the body weight gain sometimes goes up very quickly. But it is also very important to know why this is happening. So then we can provide a much better diet program.

Grace Jacobs [42:47] Running off of that Dr. Sung also spoke to why looking at IF system models are interesting, the state of the IF field, and where he thinks IF is going in the future.

Dr. Hoon-Ki Sung [42:56] We use some genetic models, statistically modified diabetes model or obese model. Sometimes, intermittent fasting didn't work for them, but we found that there is some different benefits from that model. So that's why we are studying more tissue, different tissue, as well as different model, but also potential adverse effect as well. You know, if we can figure out that issue, why it didn't work, then maybe we can actually develop some new drug target, or new method of intermittent fasting, or combination of a drug and maybe exercise with intermittent fasting. So that's why you know, whenever we have this issue, we actually are happier. Because if you say, you know, everything is working very well, it's not very interesting. Sometimes we don't see huge benefit, then we are very curious why genetically modified model ob/ob mouse model... which is your leptin deficient animal models... they are very, very obese, they are very diabetic, so it didn't work. In terms of the body weight, it didn't work, but glucose homeostasis, still, intermittent fasting was improving this glucose homeostasis. So that's why, even if there is no body weight benefit, maybe some other benefit is existing. But in the future study, we want to study the molecular mechanism of how intermittent fasting is bringing some metabolic benefit even without body weight loss.

Grace Jacobs [44:39] The landscape of nutrition has been changing, and so far in this episode, we've explored various types of diets that have gained popularity in recent years, as well as recent changes to Canada's Food Guide. Where are we headed from here though? What is the future of food? There seems to be an increasing public recognition of the way that land is used and the ethical issues surrounding food production and agriculture, as well as growing concern about climate change. Reflective of this, several companies are bringing meatless meats to the mainstream with features that make them more like meat than ever before, including similar textures and even bleeding, which is an effect created with beet juice. Meatless meats are made with plant based proteins from sources like potato, wheat MP proteins. The world of food science is transforming food as we know it. We want to investigate one of these new options a little bit closer: beyond meat, which is now available at A&W. So what makes it so special? Swapna chatted with Amy Khan, an MD, PhD at the University of Toronto, who also joined us for our 50th episode on medical devices. She shared why she's excited about beyond meat and what makes it stand out for her.

Dr. Amy Khan [45:41] So I'm not a vegetarian. Sometimes I like eating meat. But I've noticed as time goes on, after seeing the moral and ethical concerns regarding animal husbandry, I think I've been feeling more and more guilty about eating meat. I wanted to see if it would be possible to decrease how much meat I eat overall, and see if there was an actual acceptable meat alternative that was yummy and tasted like meat. That's a huge challenge to meet, consumers expectations about what meat tastes like, what it feels like in your mouth, if it bleeds, how it smells, how it works in a burger. I didn't think that the beyond meat burger could meet those expectations.

Swapna M [46:29] Sounded like it did meet those expectations? That is really a motivation, the ethical considerations behind it and the environmentally friendliness of those options.

Grace Jacobs [46:42] As Amy share she is a fan of beyond meat as a meatless burger both for ethical reasons, but also based on the taste.

Dr. Amy Khan [46:48] It is soo good. It looks like meat. It smells like meat. It sizzles like meat. I was watching the grill cook, cook it. I feel vegetarian sometimes feel like a second class citizen, because they don't have as much care and attention brought to their kinds of products. This burger is a burger. It looks, it tastes, it feels, smells just like meat. It's a full experience. Exactly. It's a full experience of a burger, how you envision a burger in your mind. What I like best about it is that it gives meat eaters like me, because I am a meat eater, i'm not a vegetarian, it gives me a way not to eat meat, but still feel satisfied.

Grace Jacobs [47:36] Amy is one of the many Canadians choosing to include more meatless meat, or alternatives, to their diets. What else does the future of food hold? Maclean's projects that Canadians will continue to become more informed consumers. The way that we access food will continue to blur the line between grocery store and restaurant, with the upswing of a variety of different delivery trends, and that we'll see a continuation of a growing market for greater choice and more individualized options. National Geographic commentary touches on the possibilities of gene editing edible packages, and the innovative greenhouses changing the way we grow and consume food. Another direction we see is nutrigenomics. But what is this? Nutrigenomics is the idea of a personalized diet tailored to your very own genome. Swapna sat down with Professor Daiva Nielsen, who is an Assistant Professor at McGill University School of Human Nutrition, to learn more.

Dr. Daiva Nielsen [48:24] So nutrigenomics is the science of how individuals respond differently to the foods that they consume. It can encompass two components, it can really be how you metabolize nutrients differently depending on variation in your genes. But it can also be how the foods that you eat affect the expression of your genes and how that can influence your physiology and health outcomes.

Swapna Mylabathula [48:47] Why would we want to tailor our diets to our genome?

Dr. Daiva Nielsen [48:50] It's a great question. Actually, there's some debate on that in terms of who would be able to feasibly have access to their genetic information. Right now, we're not at a time where people are routinely being tested to learn about their genetics. But we do see the availability happening more through consumer genetic tests, people do have the option of learning about this, and they do have to pay to have that testing done. But there is some some evidence that tailoring the diet to an individual's genetic profile could have some health benefits. There's some nice examples for example, caffeine metabolism, sodium response, saturated fat response, how the genetics really do make a difference in how someone will respond to those components of the diet. So there could be a health advantage in knowing that and kind of restricting either your sodium or your your saturated fat or caffeine, if you know that you would do better to restrict those components of the diet. Slso I think that neutral genomic research can reinforce some public health messages around nutrition. So we know in general people shouldn't be over consuming sodium or saturated fat, and people should be mindful of caffeine. There have been some initial studies that have not really supported that there could be more favorable effects of tailoring the diet to the genome than just following general healthy eating recommendations. There are some limitations to some of the previous work, and so we really need prospective studies where you know the genome in advance, you put people on a specific diet, and you follow them over time to look at the outcomes and their health status. Those studies are just getting underway. There is a study happening here in Canada in London, Ontario, of the success that individuals will have with weight loss if they follow a DNA based diet plan versus a control diet that's not tailored to the genome. So i'm quite interested to see what the outcome of that study will be. So there's still more research to be done to really understand the the benefits of tailoring at the genome level. But an individualized diet, it doesn't necessarily have to be tailored to genetics, you can individualize a diet based on current health status, based on current nutrient intakes. If you know that the nutrient profile of someone's typical diet is lacking in certain ways, you can individualize based on that information. So there's there's many different ways you can individualize a diet, and I do think that we will be seeing revolutions in dietetics and diet recommendations that factor in a lot more individual factors. It doesn't need to just be genetics, I think we're going in that direction eventually, that there's still some work to be done with the genetic content, but you can individualize on a number of variables. I think that's becoming more popular.

Swapna Mylabathula [51:41] So something else that I wanted to ask you was what does the Israel 21 c study tell us, and as we learn more about the field of nutrigenomics, are we finding that what we know about nutrition... for example, how our bodies respond to ingesting sugar... is really just a smaller part of a much bigger picture?

Dr. Daiva Nielsen [52:00] The Israel 21 c study is really fascinating. I think that was just such a cool investigation. The findings that came out of it are so fascinating. So for anyone who's not familiar with that study, it was an investigation of a lot of phenotypic information on individuals in terms of their their body weight status, their health status, their dietary intakes. They did continuous glucose monitoring on those individuals for a week, so that's every five minutes, you get a glucose reading of the blood sugar levels. So a lot of data, and they used very advanced computational methods with machine learning to try and understand relationships between all of that data they had collected and how someone's blood sugar would respond. So they were able to identify foods that these research participants responded to differently. In some cases, or I guess, in most cases, meals that were very similar, there were different responses at the individual level. It could have been due to many of the variables that they had in their algorithm, whether it was due to microbiome differences, physical activity differences, even considered sleep. In the paper, they talked about how even for the same person eating the same food, depending on how much sleep or how much physical activity they had done before they eat those foods, that would impact their blood sugar response afterwards. So there's so many moving parts, it's a lot of complexity to really study how someone responds to something that they consume. But it did show that one size does not fit all and people respond differently to the foods they eat. So I think in nutrition, we're in a really exciting time to understand at a finer grain level, how people respond to foods and how you can really try to increase the health benefits of a nutritious diet. For individuals, it will be a challenge, because it's not even if you have the perfect diet tailored for that specific person, there's no guarantee that they can or will follow it. There's sort of economic reasons to consider, there's the food supply, so there's a lot of effort between multiple players that will happen, I hope, for the future of food to have all these different variables considered and help people maintain and achieve a healthful dietary pattern.

Grace Jacobs [54:20] Looking forward the future food is in our hands as consumers leaning towards more choices, including ones that are ethically and environmentally conscious, together with increasingly individualized diets. We hope you learned as much as we did about the direction Canada's taking for nutritional guidelines, and the mechanisms underlying diets such as low carb, high fat, and intermittent fasting, in addition to their advantages and disadvantages. Special thanks to our episode team, James, Swapna, and Max, who was also our audio editor. We'd love to hear what you thought of this episode. Send us an email or tweet us at Raw Talk Podcast. Until next time, keep it raw.

Grace Jacobs [54:57] Raw talk podcast is a student presentation at the Institute of Medical Science in the Faculty of Medicine at the University of Toronto. The opinions expressed on the show are not necessarily those of the IMS, the faculty of medicine, or the university. To learn more about the show, visit our website rawtalkpodcast.com and stay up to date by following us on Twitter, Instagram and Facebook at rawtalkpodcast. Support the show by using the affiliate link on our website when you shop on Amazon. Also, don't forget to subscribe on iTunes, Spotify, or wherever else you listen to podcasts and rate us five stars. Until next time, keep it raw.

Dr. Hoon-Ki Sung [55:37] Surely I didn't eat the breakfast, I ate pho for my lunch.

Max Strauss [55:43] Like Vietnamese? I love me a good Vietnamese soup.