Jay Shetty & Giles Yeo ON Why You're Not Losing Weight

Have you ever meticulously counted every calorie only to feel frustrated when the scale doesn't budge, or worse, when you feel hungrier and less satisfied than ever before?

In this On Purpose episode, Jay Shetty welcomed Dr. Giles Yeo, genetic biologist, author of Why Calories Don't Count and Gene Eating, and a professor at the University of Cambridge, where his research focuses on how our genes influence feelings of hunger and ultimately, body weight. He reveals that while the physics of energy remain constant, the nutritional reality of how our bodies process food is far more complex than a single calorie number suggests.

Busting the Calorie Counting Myth

Calorie counting has been a dominant weight loss strategy since the early 1900s, popularized by Lulu Hunt Peters, a Los Angeles-based clinician. Peters encouraged people to think about eating 100 calories of pie or 100 calories of bacon, rather than just a slice. Yet Dr. Yeo warns that counting calories alone is not an effective way of maintaining a healthy diet.

Today, people are more worried about the numerical values than the actual quality of their food. Dr. Yeo told Jay Shetty that our diets have generally worsened in quality over the past decades, and calories have never been cheaper. He explained that 500 calories of fries vary enormously from 500 calories of steak on a micronutrient level.

Our bodies handle the three main types of macronutrients differently: carbohydrates, fats, and protein. The body expends varying amounts of energy in the two-step process of utilizing food: digestion (converting food into fatty acids, amino acids, and sugars to pass the gut wall) and metabolism (transporting those components to the cells for energy conversion).

Protein is the most complex macronutrient because it contains nitrogen. For every 100 calories of pure protein consumed, the body can only utilize about 70 calories, meaning protein counts are consistently 30% inaccurate due to the energy released as heat during processing.

Fat, on the other hand, is nearly 100% available. Then, the availability of carbohydrates depends heavily on fiber. Refined carbohydrates, such as pure sugar, are 98–99% available. Carbs without fiber (like white bread) require about 5% energy to deal with, while whole-meal carbohydrates containing fiber require 10%. Due to the energy investment required to metabolize different macronutrients, calorie counts are likely 5% to 10% inaccurate everywhere.

Cooking and Processing Affect Calorie Absorption

According to Dr. Giles Yeo, a major flaw in calorie counting is the assumption that the body absorbs all calories equally, regardless of how the food is prepared. He told Jay Shetty that processing and cooking drastically increase the calories available to the body.

For example, 100 calories of corn on the cob will be only partly absorbed by the body. If we desiccate, mash, or turn it into cornbread, then the body will absorb a significantly greater caloric amount. Similarly, a medium-rare steak cooked for 5–8 minutes requires more effort to extract 400 calories than the same 400-calorie steak that is minced, made into a ragu bolognese sauce cooked for two hours, layered into lasagna, and cooked again for three hours. The extensive cooking and processing make calorie extraction much easier.

Historically, cooking was beneficial; Dr. Giles Yeo explained to Jay Shetty that the invention of fire made it easier to extract energy, contributing to brain growth because humans spent less time focused on acquiring food. Today, however, the ease of calorie extraction is detrimental to our health.

The Rise of Ultra-Processed Food

The prevalence of obesity began to worsen steadily starting around the mid-1980s, and it’s inherently linked to the increasing accessibility and convenience of food. Dr. Yeo discussed with Jay Shetty that early fast-food manufacturers like McDonald's initially aimed to create an affordable, consistent product.

However, convenience gradually amplified the obesity issue through drive-throughs, supersizing, and delivery services like Deliveroo or Uber Eats, allowing consumers to order food without leaving the couch. According to Dr. Yeo, these steps increased the ability and ease of obtaining foods that also became cheaper.

Dr. Giles Yeo told Jay Shetty about the European paradox, where Americans often report losing weight while on holiday in Europe despite eating pasta and pizza. The likely factors are increased physical activity (walking more while touring) and food being predominantly made from scratch and less processed. The biologist asserted that a significant problem in the US and the UK is that 50% of total calories often come from ultra-processed, packaged foods.

Genetics, Weight, and Metabolism

Dr. Yeo told Jay Shetty that weight is more biological than people think; we inherit fat mass between 40% and 70%. This means that roughly half of our body weight is driven by biology, while the other half is influenced by our environment. Genetics dictate the efficiency of processing food and how much energy is burned vs. stored, including where it's stored.

Due to genetic factors that dictate how we metabolize food, some individuals can naturally consume more without gaining weight, while others may maintain the same weight despite eating less. Dr. Yeo explained that if someone is genetically predisposed to eating more, it will always be harder for them to lose weight compared to others. Physical abilities such as running fast are also genetically influenced and play an equally important role in maintaining or changing your weight over time.

Dr. Giles Yeo told Jay Shetty that our bodies actively fight weight loss. When we lose mass, the brain perceives it as a threat to survival and activates homeostatic measures, making us hungrier and lowering our metabolism. So, a person who lost 10% of their body weight must permanently eat less to maintain that new weight than someone who never weighed that much. The only way to increase metabolism is through exercise, and the most effective long-term strategy is to build muscle mass.

The Genetic Consequences of Fat Storage

While the genes influencing why people overeat are generally universal, the consequences of that weight gain are highly genetically and ethnically driven. Dr. Yeo shared with Jay Shetty that certain populations, like South Asians and East Asians, are smaller-framed and cannot gain as much weight before tipping into disease.

A study comparing Polynesians and South Asians in New Zealand showed that the Polynesian population could reach nearly double the Body Mass Index (BMI) of the South Asian diaspora before reaching the same risk of Type 2 diabetes.¹ Dr. Yeo explained to Jay Shetty that this difference is influenced by the capacity to store fat safely: the safest place to store fat is within the fat cells that act like balloons and grow bigger or smaller. The number of fat cells remains the same, but as they fill up, the fat is forced into internal organs like the liver and muscles. Since these organs are not designed for fat storage, our bodies become prone to illness.

Focusing on Protein, Fiber, and Sugar

Dr. Yeo explained to Jay Shetty that, instead of counting calories, there is a formula to keep you on track with your diet, and it is applicable for everyone, regardless of their culture or diet. You need to look at:

• Protein intake;
• Fiber intake;
• Free sugars.

The biologist suggests aiming for 16% of your daily energy intake to come from proteins. It can come in the form of meat, tofu, or beans, depending on your dietary preferences. However, make sure not to overeat protein if you have a sedentary lifestyle, as it will be converted to fat and can strain your liver and kidneys.

Fiber is crucial for our overall well-being. Dr. Yeo told Jay Shetty that we need to double the daily fiber intake and aim for 30 grams a day. The primary source of fiber is fruits and vegetables, so it's essential to include them in your diet throughout the day.

Lastly, the biologist advises the listeners to limit the intake of free sugars, which are detached from fiber. Some of these are orange juice, honey, or maple syrup. You need to ensure that your energy intake from sugar doesn't exceed 5%, he added.

Deciphering Food Labels and the Health Halo

As we began to understand the importance of healthy foods, some companies redesigned their packaging to give consumers the impression that their product is of higher quality than the competition. Dr. Yeo shared with Jay Shetty a few examples, such as green packages for protein chips or the prominent display of healthy foods on cereal packaging, which consumers subconsciously interpret as healthier.

The biologist advises the listeners to focus on protein when reading labels specifically. 

Make sure to also check the sugars and the various names under which it may be disguised on packaging. Then, analyze your diet over a week (including weekends) and observe your habits. Instead of obsessing over the nutrition of one specific item, this assessment allows for flexibility while maintaining overall nutritional goals.

Dr. Yeo explains to Jay Shetty that sugar isn't chemically addictive in the way drugs like crack cocaine are, so the idea of food addiction isn't accurate. While sugar does stimulate the brain's reward system (the same pathways activated by things like alcohol or sex), he argues that eating it reflects an addictive behavior, not a true biological addiction that would trigger withdrawal symptoms if stopped suddenly.

Discipline and Environment Control

Dr. Yeo highlights that strong biological and environmental forces, such as genetics and the easy availability of cheap, convenient food, push people to overeat, making behavior change essential. He told Jay Shetty, "I think willpower is simply the physiological manifestation of how much you want that item of food and whether or not you say yes or no. "

Environment greatly matters, too, especially the socioeconomic status. People in the lowest 20% income bracket are more than twice as likely to experience obesity compared to those in the highest 20%, even though genetics are the same across groups.² So, the biologist suggests two of the most effective behavioral strategies:

1. Out of Sight, Out of Mind – Control the environment you can, starting with your home. By removing tempting foods like chips or chocolate, you add friction to impulsive eating, and getting them would require extra effort, which often allows the craving to fade.
2. Plan for Cravings – Instead of wishing cravings away, expect them and prepare for them. For example, if they typically strike at 8 p.m., have a healthier option ready. Be aware that this step requires being honest about your eating habits and planning ahead to reduce temptation.

Weight Loss Drugs and the Danger of Malnourishment

Dr. Yeo explained to Jay Shetty that weight loss drugs like Ozempic are powerful because they make people feel fuller and eat less. Yet he warns they should not be used as cosmetic or "red-carpet" tools, but remain reserved for people who are genuinely unwell or at risk of disease.

The biggest risk of cosmetic use is that these drugs don't improve diet quality or habits. The biologist added that someone might eat less of a poor diet, lose weight, and still become malnourished if they miss out on protein, fiber, and essential nutrients. So, taking the drug without lifestyle changes is a form of self-starvation.

Dr. Giles Yeo shared with Jay Shetty that the healthiest way of keeping your weight under control is to stop obsessing over single foods' calories and move your focus to the bigger picture. Check your diet over the course of a week and understand its nutritional value rather than the calorie count.

More From Jay Shetty

Listen to the entire On Purpose with Jay Shetty podcast episode “Giles Yeo: The #1 Reason You’re NOT Losing Weight (Follow THIS Diet and Start Losing Weight TODAY!)

” now in the iTunes store or on Spotify. For more inspirational stories and messages like this, check out Jay’s website at jayshetty.me.

‍Disclaimer: The practices described are based on personal experiences and preliminary research. They are not medical advice, nor are results guaranteed. Individual outcomes vary, and some claims are still being studied. Always consult a qualified healthcare professional before beginning any new health, wellness, or therapeutic practice.

¹Krishnan M, Phipps-Green A, Russell EM, Major TJ, Cadzow M, Stamp LK, Dalbeth N, Hindmarsh JH, Qasim M, Watson H, Liu S, Carlson JC, Minster RL, Hawley NL, Naseri T, Reupena MS, Deka R, McGarvey ST, Merriman TR, Murphy R, Weeks DE. Association of rs9939609 in FTO with BMI among Polynesian peoples living in Aotearoa New Zealand and other Pacific nations. J Hum Genet. 2023 Jul;68(7):463-468. doi: 10.1038/s10038-023-01141-5. Epub 2023 Mar 2. PMID: 36864286; PMCID: PMC10313811. 

²Adams J. Addressing socioeconomic inequalities in obesity: Democratising access to resources for achieving and maintaining a healthy weight. PLoS Med. 2020 Jul 28;17(7):e1003243. doi: 10.1371/journal.pmed.1003243. PMID: 32722678; PMCID: PMC7386612.