Office Hours: How to Choose the Best Diet for Your Body

0:29Welcome to Office Hours. your own health. And for many of you, your family's health too. And you might not feel it all the time, but you have far more power and agency than you realize. I'm glad you're here.

0:42This episode is brought to you by Function Health, empowering you to live 100 healthy years with over 160 lab tests at just$365 a year. Sign up today at functionhealth.com slash mark and use code mark 2026 to get$50 towards your membership. Hi, Dr. Hyman. This is Christine from Pennsylvania. And I really want to start 2026 making better choices with food. But there are so many diets out there. I just don't know which one is right for me. There's so much conflicting information. can you just break down what the best diets are and who they're for? Thanks for your question, Christine. Funny enough, a few years ago, I wrote a book called Food, What the Heck Should I Eat?

1:29I wanted to call it What the F Should I Eat? But my publisher wouldn't let me. But it's the question that pretty much everybody asks and asks me, what should I eat? What's the best diet? Should I be keto? Should I be paleo? Should I be vegan? Mediterranean. What's the truth about food? What's the best diet? Well, the truth is the best diet is the one that works for your biology. We're all different. There isn't one size fits all. And the beautiful thing about functional medicine is it is personalized. It's personalized. It's about you and your unique biology. You're not a homogenous human. And that's how medicine studies things on homogenous humans, you're an individual with individual needs, genetics, issues, health concerns, all which need to be taken into account when deciding on what's the best diet for you.

2:21So functional medicine helps you understand how food affects your body. It's not based on ideology or belief. It's based on biology. So I would say don't let your ideology run over your biology, which a lot of people do. I see people, for example, be vegan and be really unhealthy and miserable. Other people can thrive on it. So really it's important to understand what's going on for you. So we're going to answer the top questions that we get about diet. We're going to hopefully provide some clarity for people feeling overwhelmed by all these conflicting advice. And we're going to get into the foundational principles first of what you should understand about food.

2:54What should everybody understand before choosing a diet? And there's some universal principles that I apply to everybody. First, eat food. You know, real food, whole food, unprocessed food. I mean, some processing is fine. Obviously, if you get a can of tomatoes, that's processed food, but it's actually something you can recognize. A can of sardines is processed, but minimally processed. So minimally processed or whole food, very, very important. Definition of food is something that helps support the health and development and growth of an organism. And honestly, what most people are eating in America today is not definitionally food.

3:29It's a food-like substance. The second principle, really important, is that food is medicine. it's not like medicine it is medicine we call this a dark matter of nutrition there are anywhere from 140 ,000 to some people say 3 million different molecules in food in different plants and foods that have biological effects on our body and regulate our health and well-being you might have heard of saying you know take turmeric which is like a spice that's using indian cooking and curcumin, which is the molecule in there, is anti-inflammatory. That's food is medicine. You might be told eat broccoli because there's molecules in there that help with detoxification like sulflorophane and they've been shown to actually prevent cancer.

4:12So you really understand food is medicine. Everything you put in your body is a drug. It's going to hurt you or harm you. The third principle is really, really important is that we're all different. So personalized nutrition is really important. We're all biochemically individual and we all respond differently to different diets. So really important. A few other key important concepts here is regulating your blood sugar is such a key concept. If you don't have a balanced blood sugar, if you have high blood sugar, high insulin, you know, a lot of starch and carbohydrate, this is going to screw up your blood sugar and blood sugar metabolism.

4:43And the reason it's important is it connects to almost every known chronic illness. And not just heart disease, not just obesity, not just diabetes, not just cancer, dementia, but also mental health. We're now finding there's whole fields of metabolic psychiatry where they put people on a keto diet and cure schizophrenia or bipolar disease using that approach. Next concept, really important, as I mentioned, ultra processed foods, what we used to call junk food, it's the real problem. It's not actually food. Technically, definitely it's not food. It's a deconstructed science project that's reassembled into things that look like food that are highly engineered to be addictive.

5:16And they're the real issue. And it's 60 % of our diet. It's almost 70 % of kids' diets and that's the real problem it's not real food it's not carbs or fats or protein or plant foods or animal protein those are those are things we should be eating the next is focus on quality like quality matters and you know if you're looking at something make sure you know what it is like if you pick up some a package and it's got 45 different ingredients and you don't recognize most of them and you wouldn't have in your kitchen cupboard just don't eat it so be careful so michael pollen said it very well. He said, if it grows on a plant, eat it.

5:51If it's made in a plant, don't eat it. Skip it, right? Yeah, lots of great sayings. Like if your great-grandmother wouldn't recognize it, you know, probably don't eat it. But what's a Lunchable or a Go-Gurt, you should probably eat that or a Pop-Tart. I didn't know what that was, right? Next, let's kind of get into some of the diets and the pitfalls, the benefits, who thrives on it, which diet may be helpful for different people. So we got a lot of questions about keto. Let's talk about keto. What is keto? Keto essentially means a extremely high fat diet, which is low carbohydrate, moderate protein.

6:20Usually about 70 to 75 % fat. And this diet's been around in medicine for quite a while. It was actually the diet that was used to treat type 1 diabetics back before we had insulin, because it basically helped them stay alive. It's what we used to treat epilepsy when no drugs would work. So it's been used in medicine for a long time, but now it's getting a lot more play. As something that can reverse diabetes, that can help with mental health issues, There's whole fields of metabolic psychiatry now that focus on this. And basically, when you eat a low-carb, high-fat, moderate-protein diet, it shifts your body from burning sugar to burning fat for fuel.

6:54So think about your body like a hybrid. You can have gas or electric. So gas is dirty fuel. That's carbohydrates. That, that's clean burning fuel. That's like electric. So you can think about your body as being able to switch back and forth. When you switch into fat burning, that's called ketosis. And when you cut carbs low enough, usually below 20 to 50 grams a day, your liver starts making ketones and you basically get this incredibly clean fuel source for your brain and your body. And it stabilizes your blood sugar, reduces insulin, helps your body tap into stored fat for energy. It helps you lose weight.

7:28It's great for dementia, diabetes, for cancer, for mental health issues. It's quite a therapeutic diet. And so what do you eat when you're on a keto diet? Well, a lot of fat. So avocados, nuts, seeds, olive oil, good quality protein, pasture-raised eggs, fish that's clean, poultry, hopefully pasture-raised, organic, grass-fed meat. All these things are great. Non-starchy veggies, you can eat those like broccoli, spinach, green, asparagus, whatever. You can have some berries, like a little bit of fruit, but not much. But you get no grains, no sugar, no beans, no starchy foods. and what happens when you get on a keto diet is people will lose weight and reduce cravings it immediately shuts off the sugar craving this is quite amazing and in not only weight loss but significant weight loss you know you can have a weight loss that i think is probably more effective than the glp ones this has been shown for example in these studies by berta health which uses a keto diet for type 2 diabetes and it's very powerful uh it'll lower your blood sugar it'll lower your insulin, it'll improve your cognitive function, mental clarity, focus, it'll reduce inflammation, it'll improve your energy, so many things that it benefits from.

8:39So what is it actually good for? If we have diabetes, type 2, even type 1, it can be very helpful if you know how to manage it. PCOS, which is a condition that women get that causes infertility and waking and abnormal periods and heavy bleeding and acne and high testosterone and very effective pre-diabetes, diabetes brain fog cognitive issues dementia we've used it in autism we use it in alzheimer's we use it in in depression bipolar disease schizophrenia cancer therapies i mean it's quite amazing as a dr siddhartha mukhaji who wrote the emperor of all maladies is doing a lot of research on keto diets and cancers and finding extraordinary benefits when people do keto they can make mistakes and it can be bad they can have crappy keto right you might be able to much dairy or not a fiber or other issues.

9:28So I think you need to be careful to eat a healthy keto diet and it doesn't have to be bacon and steak and cream. It can be a very, very healthy version. And we show what that's like in my practice at the Ultra Wellness Center and we teach people about it and you can also learn about it on our website. We have a lot of content about it. So how do I know that keto is not working for me? You might just pay attention to how your body's feeling. The first few weeks, you get what we call the keto flu, but you can mitigate that by taking electrolytes and having a lot of fluid. Because when you go keto, what happens is you stop having all these carbohydrates, your insulin levels drop, and insulin makes you retain water and sodium, or basically salt, and you retain a lot of water.

10:07So you dump a lot of water, you can get electric light imbalances, and you can feel a little like dehydrated and achy like the keto flu. But you can mitigate that by taking electrolytes, by drinking a lot of water, and that'll really help. But you can get other things. If you're not working, you might be feeling tired, you might be constipated, you might have sleep issues, hormone issues. so you just kind of watch what's happening with your body. Should we be on keto forever? I don't think so. If you can correct the problem that you're facing, great. Some people might need to be on it forever.

10:32For example, if you have a really significant condition like schizophrenia or severe bipolar disease and your body responds really well, you probably don't want to go back to doing what you're doing. So it's really a great reset for a short-term metabolic reset. It shouldn't be something I think people do forever unless you have certain conditions like epilepsy or really serious conditions. But for many people, it's worth a try. And it's very helpful for controlling a lot of issues. One of the questions that came up with listeners who submitted questions was, is the keto diet good for women dealing with hormone issues?

11:04Well, it can be, but you have to be nuanced about it. It's good for stabilizing blood sugar and insulin, which are the major drivers of hormone dysfunction like PCOS, perimenopausal symptoms, weight gain. And it can be helpful. And short term often works best, so don't be on forever. So it may be sick local keto or modified keto rather than strict long-term keto. And if you don't know it's helping, well, you'll have more energy, less cravings, improve cycles, reduce belly fat. But if it's hurting you, you also know you'll feel bad. And not just for the first few weeks when you get the keto flu, but after you adapt, which takes about three weeks, fatigue, hair loss, poor sleep, anxiety, weird periods, and then maybe a sign it's not good for you.

11:43What about long-term? Is it okay to do long-term keto? Well, for most people, it's a tool, not a permanent lifestyle. So 4 to 12 weeks is where you often will see the most benefit. But, for example, if you're type 2 diabetic, you want to be probably keto until your diabetes refers, and then you can add in more carbohydrates when you're more inbound and back-to-life resilient, but you have to be careful to watch what's happening. If you are on keto long-term and you're strict, it can cause issues with your thyroid, cortisol levels, gut function, but a lot of people do really well on it. Long-term, a better option would be what we call cyclical keto or modified keto, which is kind of low carb most of the time with some whole food carbs like sweet potatoes, fruit, squash, beans.

12:23That's kind of what I do. I don't really do keto. I don't check my ketones, but I do eat a pretty low starch and sugar diet, but I will add a lot of sweet potatoes or some fruit, things like that. And just pay attention to your body. If you feel bad, it's not working for you, so pay attention. Can you do keto and avoid dairy? Yeah, you can do keto and be vegan. You can do keto and avoid dairy. And often a lot of people do better on dairy-free keto, right? You can have dairy-driving inflammation, acne, cravings, digestive issues, irritable bowel, and you can do other fats like avocados, olives, olive oil, coconut products, nuts and seeds, eggs, fatty fish, fatty meats, non-starchy vegetables.

13:05All that clean keto can be done without dairy. And it often is more anti-inflammatory. Okay, next diet. We did keto. What about paleo? Well, this is kind of what most of us evolved with eating. We were hunters and gatherers. We didn't grow grains. We didn't have beans. We didn't have a lot of the starches. We did have roots. We had, you know, I went to the Hadza tribe and visited them in Africa. And, you know, we dug up some really fibrous root under a tree that was like a yam or something that they ate. so they eat some of that starchier stuff but it was very low in sugar and starch and basically it's a whole food anti-inflammatory of eating and it's sort of how our ancestors usually eat before we had any agriculture right before we grew anything now obviously way before the industrial revolution and and these are foods that your body is naturally designed to digest to thrive on and it avoids all you know modern ultra-processed food and industrial agriculture as best you can so what is a paleo diet?

14:04well it's unlimited vegetables fruit a good quality protein grass-fed meats poultry fish eggs nuts and seeds lots of good fats avocados olive oil coconut herbs and spices the things you're going to avoid are obviously all the processed ultra processed food refined sugar dairy because we weren't milking uh woolly mammoths or saber-toothed tigers grains which we didn't grow grains so wheat corn rice beans and obviously a lot of the industrial seed oils i don't think are great to eat because they're mostly oxidized If you can get the expeller-pressed ones, I think they're fine. But mostly industrial processing, I think it should be avoided.

14:42And when you are in paleo, you'll see a lot of benefits. There's actually a diet that's called the autoimmune paleo diet, which is really good for autoimmune disease, particularly inflammatory bowel disease, because it reduces inflammation and supports gut healing, helps balance your blood sugar, helps energy, helps with autoimmune issues, as I mentioned, and metabolic issues. So it can be very helpful for blood sugar. And people say, oh, is paleo too restrictive? Well, if you want to eat junk food, yeah. But it basically removes mostly industrial foods and just focus on quality food. What we should be eating, you know, protein, veggies, fruits, nuts, and seeds.

15:14And people who have gut issues, have autoimmune issues, have blood sugar issues, they do well on paleo. And the people who are doing it wrong may be eating too much meat, not enough veggies, overdoing, quote, paleo treats. So basically simple whole food that's anti-inflammatory. You got to eat like your health depends on it because it does. Food is medicine. And that's why I partnered with Function Health and with Sweetgreen to create a limited time menu. Now, I've always loved Sweetgreen because they make delicious food packed with flavor without compromising their values. They have real relationships with farmers.

15:47It's food cooked fresh every single day with avocado and olive oil only and absolutely nothing artificial. I looked at the data. Hundreds of thousands of Function members have showed the same nutrient caps everywhere. Magnesium, vitamin D, omega-3s, KB vitamins. These nutrients affect your energy, they affect your mood, and they affect how your body handles inflammation. And many people's levels are just off. So we built five new menu items where every single ingredient has a purpose. For example, the nutrient power plate, the spicy reset bowl, the iron boost bowl, the steady energy bowl, plus my favorite, it's my personal favorite, the omega salad.

16:23It has miso glazed salmon and avocado that's rich in omega-3s to support calming down inflammation. And it's got leafy greens, raw carrots, chickpeas to boost fiber and antioxidants. Try the function menu now at your nearest Sweetgreen or order at sweetgreen.com. And if you want to know what you need to work on, visit functionhealth.com for over 160 lab tests at just$365 a year. That's a dollar a day. This is how we get to 100 healthy years. Start now. All right, what about vegan? It's about 2 % of the population, although they have probably an outsized marketing team Because somehow the world believes that a vegan diet is the most healthy diet.

17:03Unfortunately, that's not true. It can be one way of eating for some people that do well with it and other people do not. And we have to be very careful and understand what to supplement with. And by definition, it's a deficient diet. If you are consistently vegan and you don't take the right supplements, you will become deficient in iron, in many nutrients that you need to thrive. And you can be low on iodine. You can be low on iron. you can be low in b12 you can be low in omega-3 fats so you want to be really careful what do you eat if you're a vegan well it's just plant food vegetables fruits whole grains beans legumes you know lentils chickpeas black beans nuts and seeds plant-based oils herbs spices plant-based protein powders you don't eat meat you don't eat poultry you don't eat fish you don't eat seafood you don't eat eggs you don't eat dairy and honey some people don't eat honey because bees make it i guess i don't know and there's a lot of reasons people can be vegan be ethical and i can't argue with that if you philosophically believe that you don't want to hurt animals i respect that but you have to realize that when you're growing and i wrote about this in my book food fix if you're growing vegetables in america more anywhere and you're doing it at scale you're using machines you're killing the soil you're using combines to to pick things and you're killing a lot of animals you're killing rodents you're killing birds you're killing obviously insects you're killing all kinds of of of animals.

18:26In fact, there's about 7 billion animals estimated to be killed every year in the growing of vegetables. You can't kind of get out of the cycle of life that you're in. Environmental concerns, I think that this is a long conversation. I wrote a lot about it in my book, Food Fix, and I'd encourage you to check out the new version, which is coming out February 2026 called Food Fix Uncensored that I co-authored with my wife. I get a revised version, Brianna, and it's quite disturbing when you kind of look at, you know, what is the truth about environment? It's not actually animal agriculture itself that's inherently bad.

18:58It's how we do it. Someone said it's not the cow, it's the how. So industrial capo or feedlot farming or growing of animals is really bad. It's bad for you. It's bad for the environment. It's bad for the animals. It's just bad. But regeneratively raised animals or grass-fed animals, very different, very different impact. And they've been shown to actually reduce carbon emissions. If you look at a regenerative, this was a life cycle analysis done by an independent company, looked at Impossible Burger, which is made from soy and industrial soy specifically, which is, you know, GMO soy, pesticides, herbicides, all that stuff, versus a regeneratively raised burger, which means you grow the animal in a way that's close to mimicking nature as possible, moving them around from different fields and, you know, basically almost wilding them.

19:45found that you had to eat one impossible burger. If you did that, you would add three and a half kilos of carbon to the atmosphere. If you ate a regeneratively raised burger, you would remove three and a half kilos of carbon from the atmosphere. So you have to basically eat one regenerative burger to offset the carbon emissions of an impossible burger. So it's really important to understand that there's ways of raising these animals that can be done at scale in a way that's very, very important. Now, if you're vegan, I would encourage you to do function health labs because you can be deficient in a lot of nutrients that we check, including B12, which is the most common, iron, because plant-based irons are really hard to absorb, omega-3 fats, and you get some from plants, but not really converted well and not the forms we need, low in zinc, low in iodine, low in vitamin A.

20:31We have a lot of things that are really important, low in vitamin D. And vitamin D comes from things like fatty fish or the sun, which if you're in the sun, you'll get it. that often can be low in protein and low in muscle mass, which is a problem, and low in choline. And these are all important nutrients for your health, for the brain, for your body. Now, if you're looking at the question of, can you be healthy on a vegan diet? Well, the answer is yes, but you have to supplement and you have to be a whole foods-based vegan diet. You can't be a chips and soda vegan. You have to really know what you're doing and it's a lot of work.

21:03And you need to look at the nutrients that are really deficient in these people, which is B12, iron, omega-3, zinc, protein, choline iodine and a lot of others that can be a lower insufficient now some people actually feel worse on a vegan diet and actually can gain weight because they're eating a lot of carbs they're eating lower protein they're having higher blood sugar spikes and they often are having to rely on ultra processed vegan junk food which is not good and it's hard to to go out and be in the world and be a vegan when you do your function health labs you're going to check a lot of the things that you need to know you know your iron status your omega-3 status your b vitamin status B12 status.

21:40You can look at zinc. You can look at, you know, vitamin A and a lot of other nutrients that are really important. So the key here is that a plant-based size can work, but only when it's real food and real plants, not processed, fake food. And be aware of what you need to supplement and make sure you're getting a protein and your muscle mass is good. You want to do DEXA scans. You don't want to be just kind of hoping it's going to be good for you. And notice how you feel. A lot of people don't feel well. I had one patient who was in infertility because she wasn't getting the nutrients she needed and she was able to actually start eating animal protein again and got pregnant.

22:12Now, is it possible for vegans to have great bodies without protein powders? This is a great question. It can be possible, but it takes a lot of work and you need to combine a lot of different plant proteins, beans, lentils, seeds, whole grains, and probably a lot of things like tofu and tempeh, which are concentrated sources of protein to meet your need for amino acids in the right balance so that you can actually build muscle. The data is really clear. If you eat a vegan diet compared to an animal-based diet or a diet that includes animal food, you are not going to be able to build muscle as well on a plant-based diet compared to a diet that includes animal protein.

22:49It's just what the science shows. It's not my opinion. It's just a fact. Now, what happens is a lot of people who want to do muscle building will use protein powders, And you can't probably get enough beans and lentils and grains to actually get the protein. You need to really build muscle unless you supplement. And you want to get about 30 grams of protein per meal and quality protein. And plant proteins have low leucine, which is a really key amino acid that stimulates muscle synthesis or muscle growth. So if your muscles aren't being stimulated, then you're not going to grow. And if you don't have leucine, you're not going to grow muscles, which is really important for longevity.

23:26If you're plant and you have whole foods, if you're a vegan, that's fine. Protein powders can be helpful for athletes or other people needing higher protein, but some of these plant proteins are full of lead and other contaminants. So you really got to be careful of what you're doing. And they're going to be full of other added ingredients and weird stuff. So really be careful and just listen to your body. You know, like how are you feeling? You know, are you tired? Are you weak? Are you cravings? Are your muscle loss? Are your hair thinning? How are your nails? Like pay attention to what your body's telling you.

23:53It's the smartest doctor in the room. Now, what about tofu, soy? Does that affect estrogen? Big question. Basically, no. If you're eating whole traditional soy foods, tofu, tempeh, amame, miso, natto, these are fine. If you're eating, like drinking a gallon of soy milk a day, that's not normal. Most people don't do that. I never did that historically. And all the industrial soy, also I would stay away from a lot of industrial hydrolyzed proteins and soy, quite harmful and can be carcinogenic. In fact, A study of the NIH showed that when you fed animal rats whole soy, they were fine, prevented cancer.

24:30But if you increased the processed soy, it actually increased cancer. And these are breast cancers. Whole food soys don't raise estrogen levels. They can actually help reduce cancer risk in women that are hormone-related cancers. So don't worry about it. They have something called phytoestrogens, which sound like estrogen, but they're basically more like blockers. They block the stronger harmful effects of the estrogens we're exposed to, both environmental chemicals, which are estrogen-like, or from our own estrogen. So when you're choosing soy, have organic whole food soy, not processed soy oils, or soy protein isolates, or fake meats, those are bad.

25:06Now, some people do have soy allergies, so beware. That's in your body, but otherwise, I think it's fine. All right, now, there's a couple more things we're going to cover. One is the Mediterranean diet, and you hear a lot about this. It's the most researched diet in the world, but I want to kind and I do a caveat with that. Because it's the most researched diet in the world, doesn't mean it's the best diet in the world. Now, what is the Mediterranean diet? Who knows, right? It could be pizza and pasta or it could be fish and olive oil and vegetables, right? So countries like Greece, Italy, Spain, I love because they have really delicious food.

25:37And people who eat in this way, in a traditional way, have a longer life, they have better health, they have lower inflammation. So in a good Mediterranean diet, not a pasta and pizza diet, but a good Mediterranean diet be lots and lots of veggies lots of good fruit lots of extra virgin olive oil fish and seafood nuts and seeds lots of beans lentils herbs and spices and they do have meat they have whole grains some and eggs and poultry and and they do have meat i mean i was in sardinia they served you know lots of pork and pig uh and they have prosciutto and all kinds of stuff so they do eat that stuff red wine is optional i don't think wine or alcohol is a health food i think the Everything else they do is so good, and they drink wine, and they live long, but it's not because of the wine.