How many times have you heard that a certain diet is going to be the best way to lose weight? If you spend any time on social media at all, you've probably even heard about the latest fad.

Here is the only weight loss technique that actually works. It's intermittent fasting.

Intuitive eating example. Check this out in case you're sick of dieting, but you'd like to get to and stay at your happy weight.

Ladies, if you're serious about losing body fat. Here's why protein is going to be your BFF.

If you follow a ketogenic diet, you will lose weight very fast.

This is nothing new. Dieting fads or tricks have been around for centuries. In the 20 years that I've been a health journalist, I've heard about so many different types of diets. It's amazing. All of them claim to be the next big thing, but I think in recent years, even more Americans than ever are trying dieting. And perhaps that's no surprise. After all, obesity rates continue to rise. But that is also the issue, right? Obesity rates are rising despite more people dieting. And at the same time, most people realize that dieting rarely leads to long term weight loss. It is a vicious cycle. One study shows that as many as 80% of people who lost weight through dieting and exercise regain most of that weight back. And then there is the yo yo nature of all this, which can make subsequent attempts to lose weight even more challenging. So then what is the solution?

The US population would do best getting rid of the crappy carbs and adding healthier fiber containing carbs and healthier unsaturated fats.

Christopher Gardner is a Stanford University professor. He has spent decades studying nutrition and all the different ways that people eat. If you Google this topic, his name is sure to pop up because he is sort of a superstar in this health space. Now, the message you just heard from Professor Gardner may sound pretty simple. It may sound like something you've heard before, but here's the issue" most people still don't do it for all sorts of different reasons. And to be fair, I know that actually eating a diet that prioritizes whole foods and fruits and vegetables is sometimes easier said than done. But here's the thing that really made me want to speak to the professor. His research shows that two people following the same exact, quote unquote healthy diet can have wildly different results.

Somebody gained 15 pounds and somebody lost 50 pounds and everything in between.

Now, why would that be? If eating a quote unquote healthy diet isn't enough for everyone? Where does that leave us? In order to answer that question today, we're going back to the basics. I'm Doctor Sanjay Gupta, CNN's chief medical correspondent. And this is Chasing Life. There's this golden rule in the dieting world that the solution to losing weight is to burn more calories than you eat. It's simple: calories in, calories out. So I decided to start there by asking Professor Gardner if a calorie deficit was in fact necessary to lose weight.

It is not the only thing, but it is the main thing. And it's mostly diet, not exercise, because exercising makes you hungrier and you eat more calories. So there's a really nice summary, Sanjay. In 2013, that was the combination of the American Heart Association, the American College of Cardiology, and the Obesity Society. And they had summarized all the evidence for diets. And they had like 20 different diets, and they had all the papers on them. It was very methodical. They said there's more evidence for some than others. Some of the studies are higher quality than others. And at the end of the day, they said, bottom line is, on every one of these diets, people lose weight when there's a calorie deficit. That was one of the main conclusions, and it was sort of as simple as that.

All right so counting calories is the main thing as he said. But it's not the only thing. There is more to this story.

Okay, Sanjay, we have done a mathematical formula. And based on your age and weight and physical activity level and and gender, you probably need this number of calories a day to maintain your weight. And I'm going to say it's 2800 just for the sake of argument. And so to lose weight you need to be in a calorie deficit. So we're putting you in this program. And if if you want to lose a pound a week, it's going to be have to have to be a 500 calorie deficit per day. If you want to lose 2 pounds a week, it's a 1000 calorie deficit and your immediate reaction should be, Holy crap. You want me to eat every single day? 500 calories or a thousand calories less? I'm going to be hungry all the time. This sounds miserable, right? So psychologically, you're you're not setting yourself up for success very well.

Losing the first pound. That's easier than losing the second pound, which is easier than losing the third pound. And so on.

So let's say you wanted to lose 20 pounds and you managed to get a 3500 calorie deficit. You would probably lose about. And maybe the second pound would come off with a 3500 calorie deficit. But the further you go, it has to be a bigger and bigger and bigger deficit. And that's why because people's bodies react to that and they become more metabolically efficient. And so the same calorie deficit won't do it for you. That's why people's weight loss starts to plateau. You can't just disappear. You can't just have a 3500 calorie deficit and all of a sudden be gone. So the longer you do this, and the more weight you lose, the more discouraging it becomes, because it actually takes more effort to lose the next pound, which is psychologically demoralizing for some people.

This means if you're following the same diet over time, it will actually be harder for you to lose weight. Our bodies are going to fight us every step of the way. You see, your body wants to hang on to weight. It's part of survival. And here's where it gets even more interesting. Professor Gardner's research suggests that even when different individuals follow the same diet, the results can really, really vary.

'It's called DIET FITS. Let me see if I can remember the acronym - diet intervention, examining the factors interacting with treatment success. And so this has been based on a previous study that we've done called A to Z. And A was Atkins and O's Ornish and Z zone. And T was a traditional health professionals diet. And in the original study comparing a bunch of very popular diet books that were New York Times bestsellers other than the traditional approach, 75 women aged 300 altogether for a year had tried these books, and the difference between the diets was just a few pounds. But the difference within each diet was 60 pounds. Like somebody getting the same advice had dramatically different results than somebody else, and very specifically from the onset. We said, we know in this world of of trying to lose weight that there's a calorie balance issue. And what we really want you to find is a diet approach that you don't just do for this study, but you maintain afterward. If you only do it for the study, if it's only a diet you go on and then a diet you will go off when you're done. That won't help. It has to be something that you can maintain. So we don't want you to be hungry. We want you to eat till you're satiated. And if you are still hungry, we're going to ask you to look us in the eye. You're not done. You're gonna. You might have to add on your low carb diet, more carbs back on your low fat diet, more fat back. And that's where for you, socially, you can't be hungry all the time. They lost 6,500 pounds collectively. They lost 12 pounds on average. And in the end, we saw the same thing. And low, healthy, low carb and healthy low fat. Somebody gained 15 pounds and somebody lost 50 pounds. And everything in between. Now is this huge range of variation.

I want to make sure you got that. Even when following the same diet, some people gained 15 pounds and some people lost 50. The same diet followed closely to make sure it was the same diet, and it still had this huge difference. Why? Well, Professor Gardner believes there is another absolutely critical predictor of success. And that is not only how much you are eating, but how hungry you are after you eat. It's called satiety. Do you actually feel full?

I haven't quite figured out how to do this study yet, but I. I think it's hugely satiety or satiation. And there's there's two aspects of this. One is stop eating sooner. Now I'm going to miss the word on this. There's a great Japanese word for eating till you're 80% full.

Hara hachi bu.

Thank you very much. Okay, so that's the word I knew I was going to blank on. And then the key is: when is your next meal? So are you satiated? For a long time. You'll hear some people say, I had this thing and it was great, but oh my God. An hour later I was hungry and I had to eat again. So kind of the key to this calorie deficit is stopping your meal soon enough to not overeat and having a long enough space till the next meal so you're not making up for that calorie deficit in the next few hours. I think satiety is a huge factor here. I often ask people in some of my talks, would you be more full and for longer on steel cut oats with nuts and berries or with cheesy eggs? And Sanjay, I often get half the audience saying one and half the audience saying the other. It's actually surprised me how many times I've seen the room split. Like, these are very different breakfasts. I am here, but I didn't test it. I just asked sort of what their perception was and their perception was very different.

And I mean, I guess the obvious question is, why do you think there is such a split and just basic things like that? Steel cut oats, nuts, berries, things like that versus cheesy eggs. I, I have my own answer, I think, but I'm just like, why the perception difference?

My hunch is there's something really about satiety that's different if you choose healthy. So I throw up, everything goes out the window. If one group is choosing a healthy version of one diet and a crappy high sugar, high white flour version of the other, and they're both choosing the healthiest foods in that group. It will work for some of them, and it won't work for others. And I think there's some satiety or satiation here when you say, well, God, if you're so convinced of this, why don't you test it? And we have horrible metrics for satiety.

Now, for what it's worth, in my mind, I'm more of an oatmeal guy. But I think Professor Gardiner raises this really fascinating point that what we find most satiating can really vary. And that means it's really important to choose foods this way. The healthiest options, yes, but also the ones you know are going to be the most filling for you and your body. So how do you find the foods that are most satisfying, most satiating for you? I'll ask Professor Gardner after the break. I think I know how you can answer, but when you put it all together, is there a type of diet that does seem to be generally the most effective? Again, people will vary. But you know, you talk about keto, you talk about paleo. There was an article that just came out today on intermittent fasting. What do you think? And maybe I'll take even a step further and ask, what do you do? How do you eat with all that you know?

Yeah. So my answer would be my diet is a whole food plant based diet. And let, let me frame it this way. So there's another publication that's, from maybe 2019, 2020 from the Journal of American Medical Association that I have been showing almost every talk I've been giving for the last few years. And it's very fun because it's American trends of protein, carbs, and fats over 20 years. In this particular paper, they started by showing proteins, carbs and fats. And so the the range has been very stable or the levels have been very stable over those 20 years, and it's pretty much around 18% protein and around 30% fat and around 50% carbohydrates. And that's the main graphic. And then the next graphic is types of protein, types of carbs and types of fats. And so the protein is almost always about 10%, animal protein and 6 or 7 plant protein ish. But call the plant ten for now just so that we have ten and ten, let's call it 20% protein. The fat very consistently 10% mono unsaturated, 10% polyunsaturated, 10% saturated, ten 1010. So that's 30. The carbs is about 10% good healthy carbs. So now we have ten, ten, ten, 10%. That's 60. 40% is crappy carbs. 40. Like, it, like, hits you over the head. Everything else is ten. And the added sugars and the simple, quickly absorbed refined carbohydrates are 40. And so here's my take: if you eat a plant based, it could be vegetarian, could be all the way to vegan. I'm happy to go into that, but I'd really rather just say sort of whole food plant based, not a lot of junk food. If you were to get rid of all 40% of the added sugar and the refined grains that are sort of the crappy carbs that are in this graphic, I posit to you that a couple of people would do great doing all that with healthy carbs. They just wouldn't have any more fat. This would end up being a low fat vegan diet. And a couple of let's say I took 100 people. 2 to 5 would be okay there. And then we got some keto people who are doing all that fat. They replaced all the 40% with fat. So now it's a very low carb diet and very high fat diet, and 5% would do great. And they'll be very vocal on social media, and there will be a social influence of media influencer to say that, that 90% of the population would benefit from some balance. So take those 40% and make some of them healthy carbs, whole grains, beans. God. Americans don't eat enough beans. More beans, more vegetables and some more avocado. Some whole fat yogurt, some fatty fish, some nuts and seeds. So healthy fats and healthy carbs take that 40%. And I think in that range, you would find different people succeeding on what looks like very different diets because of most of the 40 was fat, or most of the 40 was carbs, but not all of it. Like the extremes only work for a couple people, but they do, and they're very vocal when it works. But the US population would do best getting rid of the crappy carbs and adding healthier fiber containing carbs and healthier unsaturated fats, which means you could be Mediterranean around quite a range. But it's it's not all the packaged, processed crap that we get in the US, which is 40% of calories.

I've been a medical reporter for over 20 years now, and I feel like we try and give really helpful health content, with regards to how people should nourish themselves. And I think that if you talk to people, I think they generally agree that the majority of our diet should come from whole plant based foods as much as possible, and yet we still don't do it right. So the it's not an information gap out there, I don't think I think most people know what what they should eat. What what do you think's going on?

I think it's a food environment. 24/7 we're advertised with convenience foods that the food industry has made tasty. If you layer salt, sugar and fat on top of each other in complex ways in inexpensive, convenient foods. It's really hard to turn those foods down. The old lays potato chip out if you can't eat. Just one was very intentional. It was made so it would fire dopamine reward pathways in your brain and you would want another one. You couldn't have one cookie. You wanted the whole sleeve of cookies, did you? Did you mean to do that? No. Not really. But so the most fun I've been having, Sanjay, is addressing this taste issue. So I think it's a huge problem in the US is that health and taste have been dissociate. You ask someone what they would like and aspirationally they would like to eat that way, but they like good food that tastes good and they will tell you I'd rather have the better tasting food than the healthy food, which is a little mind boggling to me because there's amazing amount of great tasting healthy food.

So with all the caveats you've given about calories and and they matter to a point. But after a while, your body starts to acclimate to reduced calories. So how much you eat and what you eat? We've talked about what about when we eat? Is there merit to intermittent fasting?

So the intermittent fasting thing, the data, you know, I don't I don't know how much time. We probably don't have another hour to go into this. But the data are not very compelling, in my opinion, for intermittent fasting. And part of the reason it's not compelling is because of all the versions. So if I could just quickly run through sort of the Valter Longo five days of fasting a month out of 30 days or another type is a full fast for two days a week out of seven days every week. What seems like the more popular is the type of fasting that's within a 24 hour period. It's called time restricted eating. It's either a normal window of eating might be 16 hours for a person, so 12 or 10 or eight would be time restricted. Eating. Seeing that they stick to that can be a little difficult, but I haven't seen any studies where they've really compared the eight hour to the ten hour to the 12 hour window for what? And for how long is it for weight or is it for fatigue or is it something else? It's a hard thing to study and publish with clean results of the studies that are published. I'm not really very impressed, and I am very concerned because the intermittent fasting, the allure of it, as I understand it, is of all the things that your listeners have been hearing me say today, like, oh God, that guy from Stanford is so friggin confusing. You said, like everything under the sun, there's like too many rules. Intermittent fasting. You look at your watch. Is it time to eat? No. Okay. I'm not going to eat. Wait, let me look again. Oh, I get to eat now, and there's no emphasis on quality, right? So if it's just a window, I fear that people say it's the window so I can have the pint of ice cream, or I can have the cookies, or I can have whatever, because the most important thing is the window. And I really appreciate how simple that rule is. And it it is really helping me because I'm not eating the rest of the day, and it is a trick to help me achieve that calorie restriction by just saying, it's not time to eat. And you alluded to this before, there's actually two terms appetite and hunger. Hunger is a physiological state. Appetite is I could eat something. I saw a billboard. I'm actually or we all know that second stomach we have and felt like I didn't have another bite of dinner. But dessert? Oh, I could totally have dessert. I have, like, a second stomach. I don't have hunger for dessert. I have an appetite for dessert because you just showed me the dessert tray, which is so undermining.

Hey, look, I've done so many interviews about this topic, but this point that you've made a few times now about satiation, which makes total sense to me if it fits. I think that that's a really important takeaway here. And to add a little bit of texture to it, to remind the audience that that it takes a little bit of time again for satiation to set in. So with the hara hachi bu, the reason that they said eat to your 80% full is because within a certain amount of time, 15, 20 minutes, whatever it may be, you will feel 100% full. So never stuff yourself. Which which I think I don't think that's the one size fits all sort of dietary plan that people probably want, but I think it goes it goes a long way. Obviously pay attention to how many calories you're eating. Pay attention to the quality of the calories that you're eating. Maybe if you care about it, pay attention to when you're consuming those calories. But for the most part, let your brain and your stomach work in some sort of harmony here. It's a system that works if you let it sounds like.

Totally agree. And I have one more tip for the listeners here, and it's something that I hope you'll like. The phrase stealth nutrition. Stealth nutrition is actually something I learned from teaching Stanford students. And a colleague of mine and I, Tom Robinson, decided to teach a class called Food and Society. We shook hands and said we won't ever talk about health. He's a pediatrician. I'm a nutrition scientist. We're only going to talk about, the environmental consequences of food, animal rights and welfare, human labor issues and slaughterhouses and the way fast food workers are treated. And we're not even going to find scientific papers. We're going to find popular books by Michael Pollan and Marion Nestle and Eric Schlosser and Jonathan Safran Foer and have them. It's going to be a discussion based class, and we're just going to find the readings for them and let them discuss them. Almost every student in the class changed their diet. Some went vegetarian. Some only bought grass fed beef because the environment, some of them stopped going to fast food restaurants. Never for health. All for these other reasons. And so I really like the frame of stealth nutrition, not in a deceitful way. So the stealth part isn't deceiving them. The health part is pointing out how many societal consequences are at your food choices. So imagine that you started your diet for the week, and you see that chocolate chip cookie and you say, I can really start the diet tomorrow. I don't really have to start today because if I wait one more day, it only affects me. Once you take this course, the students say, oh my God, my food choices affect society. So if you have these societal impact influences out there to help you stick with that choice you're making. So please, let's put healthy and good taste back together. Let's think about societal impacts of that. And that's bio hack our satiety a little bit. I think those hints would go a long way.

'Those are great takeaways, professor. And it rings true. You know, I think about a whole, a plant based, a whole food diet for my health. You and I both share this concern about heart disease again with my three teenage daughters, when I talk to them about food, they. They echo exactly what you said. You're absolutely - I mean, it's interesting. They care about the world. They care about the environment. I say this look at how much water it takes to make a hamburger. You know, whatever it might be, whatever sort of thing clicks with them, and they really take it to heart. I see it how it affects their food choices. And again, they're not thinking about health and they're not even thinking about weight. They're thinking about a larger a larger ecosystem, which is, I think, actually kind of inspiring if young people are thinking that way.

So, yeah, I really think that's true that that. And if you start thinking that way about food, I'm gonna have to start thinking that way about Democrats and Republicans and war. And like this broader thinking about food, more sensible will just sort of feed into some of the other issues in the world. And we'll all sit down and have a great tasting healthy meal together.

[laughs] You know I got to say, I really enjoyed that one. I enjoyed the conversation with Professor Gardner. I learned a lot. Think about calories, yes. But also really think about the foods that make you feel full. Really pay attention to that. And coming up next week on the podcast, we're going to talk to someone who's been doing a lot of thinking about diet culture. Actress and activist Jameela Jamil.

It's not a noble crusade, it's I'm just protecting my mental health. I don't want to see images of what I could look like if I were more attractive and perfect. That's not good for anyone.

That's coming up on Tuesday. I hope you'll join us. Chasing life is a production of CNN audio. Our podcast is produced by Eryn Mathewson, Jennifer Lai and Grace Walker, our senior producer and showrunner is Felicia Patinkin. Andrea Kane is our medical writer and Tommy Bazarian is our engineer. Dan Dzula is our technical director. And the executive producer of CNN Audio is Steve Lickteig. With support from Jamus Andrest, John Dionora, Haley Thomas, Alex Manesseri, Robert Mathers, Leni Steinhart, Nicole Pesaru, and Lisa Namerow. Special thanks to Ben Tinker, Amanda Sealy, and Nadia Kounang of CNN Health and Katie Hinman.