Habits and Hustle - Episode 510: Layne Norton, PhD: The Best Diet to Follow + Is Diet Coke Actually Bad For You

Episode Date: December 12, 2025

Ever wondered which diet actually works? Or if artificial sweeteners are as dangerous as the internet makes them sound? In this Fitness Friday episode, I sat down with nutrition expert Dr. Layne Norton to cut through the diet noise. We break down why personalization beats every trend, what the research really says about diet soda and sweeteners, and why the “best diet” looks different for every person. If you want straight answers, not fear-based headlines, this conversation will challenge a lot of what you think you know. Dr. Layne Norton is the founder of BioLayne, a company built on science-driven coaching and real-world experience. He has coached more than 70 athletes to pro status and helped thousands rethink nutrition with evidence instead of hype. Layne holds a BS in Biochemistry and a PhD in Nutritional Sciences, where he trained under one of the leading researchers in protein metabolism. What We Discuss: (00:00) The truth about the best diet for weight loss (00:38) Why adherence drives long-term results (03:29) How to find the diet style you can actually sustain (06:56) Diet soda and real weight-loss evidence (08:25) Artificial sweeteners and gut health research (10:41) What aspartame really breaks down into Thank you to our sponsors:   Therasage: Head over to therasage.com and use code Be Bold for 15% off  Air Doctor: Go to airdoctorpro.com and use promo code HUSTLE40 for up to $300 off and a 3-year warranty on air purifiers. Magic Mind: Head over to www.magicmind.com/jen and use code Jen at checkout. Momentous: Shop this link and use code Jen for 20% off  Manna Vitality: Visit mannavitality.com and use code JENNIFER20 for 20% off your order  Prolon: Get 30% off sitewide plus a $40 bonus gift when you subscribe to their 5-Day Program! Just visit https://prolonlife.com/JENNIFERCOHEN and use code JENNIFERCOHEN to claim your discount and your bonus gift. Amp fit is the perfect balance of tech and training, designed for people who do it all and still want to feel strong doing it. Check it out at joinamp.com/jen  Find more from Jen:  Website: www.jennifercohen.com Instagram: @therealjencohen   Books: www.jennifercohen.com/books Speaking: www.jennifercohen.com/speaking-engagement Find more from Layne Norton, PhD:  Website: www.biolayne.com Instagram: @biolayne

Hi, guys. It's Tony Robbins. You're listening to Habits and Hustle. Crush it. Hey, friends, you're listening to Fitness Friday on the Habits and Hustle podcast, where myself and my friends share quick and very actionable advice for you becoming your healthiest self. So stay tuned and let me know how you leveled up. Before we dive into today's episode, I want to thank our sponsor, Momentus. When your goal is health span, living better, and longer, there are very few non-negotiables. One of them, quality. And when it comes to supplements designed for high performers, nobody does it better than Momentus. Momentus goes all in on NSF certification.

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Now, if we look at does one diet stand out as better than the others, so there's two studies I'm thinking of. There was one looking at four different diets and one looking at 14 different diets. Both were systematic reviews, and they looked at long-term weight loss. And what they found was basically no diet performed better than another diet. But in one of them, they stratified people, regardless of diet type, from least adherent to most adherent. And wouldn't you know it?

From least adherent to most adherent, there was a linear reduction in body weight. So again, I know this sounds very much like a cop-out, but whatever you can stick to, whatever you can sustain is going to be the best diet for you. Now, that appears to be extremely individual. I've had people say to me, I did intermittent fasting, and I didn't even feel like I was dieting. I've had people say, I tried everything, and I did low carb, and it felt easy. I've had people say, I did a plant-based diet, and I was saying, so full all the time. It felt easy. If you're going to lose weight and keep it off, you have to

follow some form of restriction. But you should choose the form of restriction that feels the least restrictive to you and also don't assume that it'll be the same for everybody. So for me, I tried the whole eat clean 20 years ago when I was getting into bodybuilding when I found out was I was binging on the weekends. And I remember one day I just had like mowed down a whole pizza and I was like, you know, I feel like it's not the pizza itself that's, you know, screwing me up. It's the fact I'm eating the whole thing. Yeah. So I'm going to try and hit these calories and protein and carbs and fats and let myself,

if I feel like I want something, let myself have it. And wouldn't you know it? I had no problems after that. And you were able to stop at just a little amount? Yep. Now, that's my personality, my psychology, right? So I'm somebody like, if I know I can have it, it makes me actually want it less. Right? So I track my calories. I track my protein. I track my carbs, my fats. Now, for some people, that feels very overwhelming. It feels extremely restrictive. They just say, well, I'd rather just like reduce my carbohydrate intake and not worry about it. Okay. Yeah. Depends on who you are.

But again, but funny enough, when I got into coaching people, I thought, well, I've got the solution. I'll just have everybody do this flexible dieting thing. And this will solve all the problems. And of course, you know, learned, hey, dumb, dumb, not everyone's like you. What did you find for the people that you've trained, of all the people you've trained, what has been, what has worked the most in terms of what you've seen? Well, flexible dieting has worked the most, but that's a selection bias because people come to me because they know I'm a flexible dieting guy. Right. And so then they end up wanting to gravitate towards that. And I'll always tell people in low carb or fasting, like, they're like, look at all these people who've gotten all these results. I'm like, yeah, because they're coming to you because they're already sold on that. Exactly.

So what I would say is, like, listen, you know, I think that this is great news, personally, because it means the world is your oyster. Whatever dietary strategy helps you, like, be able to be consistent, just do that. I mean, we have, like, a nutritional coaching app that we designed an algorithm-based coaching app. What's it called? It's called Carbon Diet Coach. So it's, like, basically, like, one-on-one nutrition coaching, but for a fraction of the price. So $10 a month. That's great.

And it's all algorithm-based algorithm that I helped write. But we don't, when it comes to dietary preference, we give people options. Do you want to be plant-based? Do you want to be low-carb, ketogenic? Do you want to be balanced? Do you want to be low-fat? And you can pick, and then even within those, we let you shimmy the numbers a little bit. So you can really get to something.

And we don't say, hey, you've got to eat five meals a day or three meals a day or eight meals a day. You get to pick based on what you feel is most sustainable for you. you in terms of dietary strategy. Oh, that's great. So, you know, I really think that reframing this stuff is like we get into these diet wars. Everybody wants to be the winner and have their diet be best.

And I'm like, shouldn't the goal be to like just figure out what works for people? Right. And when people say, you can't lose fat eating carbohydrates. I'm like, how many millions of examples of people eating low fat, higher carb diets and losing fat and getting very lean do we need before we say, well, that's obviously not true. 100% true. I think people get so, and I'm guilty of this, it's like they find whatever worked for them

and then try to justify why it's the best thing to do. It's almost like we're just like, it's like teams, right? Totally true. It goes to politics, the whole thing. It goes with everything, but it's also like, because we want to, we don't, to change our mind is very difficult. Oh, yeah.

Right? And so if we have that in our brain, it takes a, is it cognitive dissonant? Is that what it's called? Cognitive dissonance. Yes. Great example of that. And this is an example.

of politics, but I think there was a study done like 10 years ago. And they showed both Democrats and Republicans facts that would either support or refute, like directly refute a position they held, right? Yeah. What they found is that whether it refuted or supported their position, both things were equally as effective as causing the person to become more entrenched in their beliefs. So when they presented facts to these people, and it didn't matter if it was Democrats or Republicans, this is a people problem. This is not a party problem. When they presented facts to Democrats and Republicans that refuted a position they held, people did not take the other side. They did not admit they were wrong. It actually caused them to double down. And that's what's called

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Okay, I didn't ask you about artificial sweeteners, like stevia versus aspirin. Because I think you did something on Diet Coke. Like everyone, because if you were at, if you hold a Diet Coke around these days, You might as well just hold like a machete and like, you know what I mean? Like, it's unbelievable. Like, God forbid you have a Diet Coke. I'm like, that's my biggest weakness is, you know, whatever. You don't think it's as bad as people think it is.

Like, it's like, right? I mean, I'll tell people, do you want to discuss feelings or do you want to discuss what the data actually says? I want the data. So if we look at the effects on like type 2 diabetes, on weight loss. So if you look at correlation data, which is basically what characteristics do people who drink more diet sodas have? Well, you can find a correlation between obesity and diet soda. And so they've gone, aha, see, it's causing people to be fat. Well, that's like saying basketball is causing people to be tall.

Right. Yeah. Right? But if we actually look at the randomized control trials where they substitute diet sodas instead of regular soda, they see significant loss of body. body weight. And actually, people say, well, it's not better than water. There was a recent network meta-analysis done where they compared diet soda versus regular soda, water versus regular soda, and water versus diet soda. The people drinking diet soda lost a little bit more weight than the people drinking water. Stop it. Now, that's, diet soda is not a fat burner, okay? They're just eating

less. So what that suggests is people are, if they're substituting with water, they're still seeking out that sweet taste somewhere else. So now people will say, well, that's just weight loss. Like, it can't be healthy for your gut microbiome and whatnot. So there's only a couple studies in humans on the gut microbiome. Most of it's been in petri dishes and high-dose rodent studies. It does appear that some of these artificial sweeteners do change the gut microflora. However, what we don't know is, is it a bad change, good change, or neutral?

We don't know those things? We don't know those things. No. And I've talked to several, one of my colleagues who did her master's at Illinois when I was doing my PhD in my lab, Suzanne Def Kona, is one of the world's leading researchers on the gut microbiome. And I asked her about diet soda, and she said, when it comes to gut health, it's one of the last things I'm worried about. Really? Yeah. So, for example, so there was a study done where they showed that, you know, artificial sweeteners, I don't know if it was aspartame, I think it was sucralose.

Which is Splenda? Yeah. Yeah, Splenda. They showed that, and it does appear to be artificial sweetener dependent. I don't know if Aspartame changes the gut microbiome. There was a study looking at it. I can't remember exactly which one it was. I know Suquilose did.

But if you look at the microflora that it changed in terms of reducing and increasing, they did note an increase in the production of things like butyrate and propionate. So if you go and look at the literature on buterate and propionate, guess what? They actually appear to have health benefits. benefits. So now I'm not saying that artificial sweeteners are necessarily good for your gut. What I'm saying is we don't know. But what I'll tell you is this. If I can get somebody to stop drinking regular soda and drink diet soda and they lose 50 pounds, and every time I post about this, there'll be multiple people say, all I did was cut out regular soda and drank diet soda and I lost

50 pounds, 70 pounds, 100 pounds. You're going to have a hard time convincing me, regardless of whatever is happening with the gut microbiome, which we don't know, that that person is not healthier now for having lost 50 pounds. That is amazing. So where did this all come from? It's the naturalistic fallacy, which is if something is artificial, it must be bad for us. But if you look at, like, what aspartatein breaks down into, it's aspartic acid, phenylalanine, and then it breaks down to the methanol.

Oh, gosh, methanol. Let me get to that. Aspartic acid and phenylalanine are amino acids. You get 20 times the aspartic acid and phenylalanine in a steak that you do in a diet soda, all right so let's just let's just take those out of it okay the methanol you it's such a small amount your body can easily metabolize it and i believe you get more methanol in like a glass of tomato juice than you do in diet soda really so because you have to understand while a coke is like 40 grams of sugar artificial sweeteners are hundreds of times sweeter than regular sugar so aspartame i think

is 200 times sweeter than sugar, and sucralose is like 600 times sweeter. So you're talking about milligrams of this stuff. It's a very, very small amount, which is why, again, when they cite these rodent studies, where they're giving a thousand times the dose of what they would normally give humans, I kind of go, who cares?

It doesn't matter. I'm not saying people should drink diet soda. I'm not encouraging it as a weight loss tool. What I'm saying is right now, if somebody wants me to say that it's bad for you, I don't think you can objectively say that. Do I think it warrants further investigation? Of course.

But again, if it's a tool that helps people lose significant body weight and keep it off, then I think it's a net win.