The Weight Loss Scientist: You've Been LIED To About Calories, Dieting & Losing Weight: Giles Yeo
Steven Bartlett (host), Dr Giles Yeo (guest), Narrator
In this episode of The Diary of a CEO, featuring Steven Bartlett and Dr Giles Yeo, The Weight Loss Scientist: You've Been LIED To About Calories, Dieting & Losing Weight: Giles Yeo explores why Your Brain Fights Weight Loss: Giles Yeo Exposes Diet Myths Geneticist and Cambridge professor Dr. Giles Yeo explains why body weight is far more biologically constrained than most diet culture admits, and why our brains aggressively defend our current weight. He argues that calories are a blunt, often misleading tool and that food quality, processing, fiber, and protein matter far more than raw calorie counts.
Why Your Brain Fights Weight Loss: Giles Yeo Exposes Diet Myths
Geneticist and Cambridge professor Dr. Giles Yeo explains why body weight is far more biologically constrained than most diet culture admits, and why our brains aggressively defend our current weight. He argues that calories are a blunt, often misleading tool and that food quality, processing, fiber, and protein matter far more than raw calorie counts.
Yeo dismantles popular myths around keto, juice, gluten, alkaline diets, veganism, and exercise-as-weight-loss, replacing them with evidence-based, nuanced principles that can be applied to almost any eating pattern. He stresses that sustainable change comes from working with, not against, human biology and the food environment.
Beyond individual choices, Yeo frames obesity as a global public health emergency driven by cheap, ultra-available calories and policy failures, not simply personal irresponsibility. His mission is to destigmatize obesity so policymakers can rationally address food environments, affordability, and support.
Throughout, he emphasizes that loving food, maintaining muscle, and modest, realistic dietary shifts (especially more fiber, adequate protein, fewer added sugars, and slightly less meat) will do far more for long-term health than perfectionism, restriction, or pseudoscientific fads.
Key Takeaways
Your Brain Defends Your Current Weight—Expect a Rebound Fight
When adults lose even a small amount of weight, the brain perceives a threat to survival and deploys automatic mechanisms to restore the prior weight. ...
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Calories Are Crude: Focus on Protein, Fiber, and Added Sugar
A calorie only tells you how much energy is in food, not its quality or how your body will process it. ...
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Food Processing Changes How Many Calories You Actually Absorb
Caloric availability—the energy you can extract from a food—depends heavily on processing and cooking. ...
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Not Everyone Can Reach (or Maintain) the Same Body Size
Body weight is influenced by hundreds to thousands of genes, including key pathways like leptin and MC4R that regulate hunger and fat sensing in the brain. ...
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Exercise Helps Maintain Weight Loss, But Won’t Do the Losing for You
For most people, exercise is a poor primary strategy for losing weight. ...
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Fruit Juice Isn’t a Health Drink—Eat the Fruit Instead
Orange and apple juice have roughly the same sugar concentration as Coca-Cola (~12%), and the sugar is biochemically the same. ...
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Obesity Is a Systems Problem—Make Healthy Food the Easy, Cheap Default
We now live in a 'feast–feast' environment where calories are cheaper and more available than ever (about 1,000 calories for 90p in the UK). ...
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Notable Quotes
“Everyone's brain hates it when they lose weight. The moment your weight starts to go down, it goes, 'This is reducing my chance of survival.'”
— Dr. Giles Yeo
“The calorie tells you absolutely nothing… I would like to see a world where we are more concerned about the quality of food we are feeding ourselves than just the pure caloric content.”
— Dr. Giles Yeo
“There is health at many sizes, but there is no health at every size. The moment you go past your own safe fat‑carrying capacity, you will become ill.”
— Dr. Giles Yeo
“Veganism, plant‑based in particular, is a diet for the privileged people who can choose to do so. We do not need everyone to be vegan.”
— Dr. Giles Yeo
“Exercise is a good weight‑loss strategy if you’re an Olympic athlete or a Tour de France rider. For muggles like you and me, it’s a good weight‑maintenance tool, not a way to lose weight in the first place.”
— Dr. Giles Yeo
Questions Answered in This Episode
You described a 'safe fat‑carrying capacity' that varies between individuals and ethnicities. Practically, how could a clinician or patient know when someone has exceeded their own safe capacity before overt diseases like diabetes show up?
Geneticist and Cambridge professor Dr. ...
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In the study you mentioned where people front‑loaded versus back‑loaded calories but lost similar weight, hunger was the main difference. How would you advise someone who naturally isn’t hungry in the morning but wants to leverage that fullness benefit without forcing big breakfasts?
Yeo dismantles popular myths around keto, juice, gluten, alkaline diets, veganism, and exercise-as-weight-loss, replacing them with evidence-based, nuanced principles that can be applied to almost any eating pattern. ...
Get the full analysis with uListen AI
You were highly critical of claims that there is 'no safe dose' of animal protein. What specific epidemiological or mechanistic evidence most directly contradicts that claim, and where do you think a reasonable 'upper limit' for red and processed meat should sit?
Beyond individual choices, Yeo frames obesity as a global public health emergency driven by cheap, ultra-available calories and policy failures, not simply personal irresponsibility. ...
Get the full analysis with uListen AI
Your three-number framework (16% protein, 30 g fiber, ≤5% added sugar) is compelling. Could you walk through a realistic day’s meals that hits those targets using common supermarket foods, including some convenience items, for someone with limited time and money?
Throughout, he emphasizes that loving food, maintaining muscle, and modest, realistic dietary shifts (especially more fiber, adequate protein, fewer added sugars, and slightly less meat) will do far more for long-term health than perfectionism, restriction, or pseudoscientific fads.
Get the full analysis with uListen AI
You’ve argued that making healthier food cheaper and more convenient is the key systemic fix. What concrete policy levers (e.g., reformulation standards, targeted subsidies, advertising restrictions) do you think could be implemented in the next five years without provoking overwhelming political or industry backlash?
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Transcript Preview
Do we get fatter with age? (drums play)
Yes. (whoosh sound) Between 20 and 50 years old, the average person will gain about 15 kilos in weight. (whoosh sound)
I don't wanna be that guy. What can I do?
Okay, so- (bell rings) Dr. Giles Yeo.
He's the world-leading expert on fat and how to burn it.
His book is called Why Calories Don't Count. What you eat does matter. (bell rings)
Let's talk about how we fix the obesity. How we burn fat. Mm. How we all get into a healthy weight. (bell rings)
Everyone's brain hates it when they lose weight. We're talking even a few pounds. It goes, "This is reducing my chance of survival." The moment you stop the diet, the weight will come back on. (drums play)
Calories are not accurate. What's the truth?
The calorie tells you absolutely nothing. Zero. (whoosh sound) So if you actually look at a stick of celery, raw, it's got only six calories. (whoosh sound) If you cook the celery, that six calories becomes 30 calories. (whoosh sound) Understand the limitations and caveats of calorie counting. (bell rings)
Veganism. (whoosh sound) What are the general stereotypes that need addressing?
Veganism, plant-based in particular, is a diet for the privileged people who can choose to do so. We do not need everyone to be vegan. (whoosh sound)
Sustainable weight loss. What is the way that you would suggest to do that? The simple way?
Okay. It is the set of numbers that you can apply to whatever diet you like. So the first is- (bell rings)
Let's talk about something else which I feel like I was lied to about-
Oh, God. (laughs)
... which is juice.
Oh, yes. (drums play)
I just wanna start this episode with a message of thanks. A thank you to everybody that tunes in to listen to this podcast. By doing so, you've enabled me to live out my dream, but also for many members of our team to live out their dreams too. It's one of the greatest privileges I could never have dreamed of or imagined in my life to get to do this, to get to learn from these people, to get to have these conversations, to get to interrogate them from a very selfish perspective, trying to solve problems I have in my life. So, I feel like I owe you a huge thank you for being here and for listening to these episodes and for making this platform what it is. Can I ask you a favor? I can't tell you how much, um, you can change the course of this podcast, the, the, the course of the guests we're able to invite to the show, and to the course of everything that we do here just by doing one simple thing. And that simple thing is hitting that subscribe button. Helps this channel more than I could ever explain. The guests on this platform are incredible because so many of you have hit that button. And I know when we think about what we wanna do together over the next year on this show, a lot of it is gonna be fueled by the amount of you that are subscribed and that tune into this show every week. So, thank you. Let's keep doing this. And I can't wait to see what this year brings for this show, for us as a community, and for this platform. (electronic music) Giles.
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