The Obesity Code: Unlocking the Secrets of Weight Loss

by Jason Fung - On the phenomenon of Obesity and how to overcome it.

I have been on intermittent fasts for the last 3 years and I wanted to know if I am doing it right. Yeah, that thought came rather late to me. Let me tell you why.

I thought I had this whole calorie deficit shit figured out and the more calories you burn, the more weight you lose. Starting in 2021 with 800 calories of workout a day I was at 1200 calories a day in 2023, when Tennis Elbow hit me. I had no other choice but to take it easy. You cannot do any exercise if you cannot move your hands; can’t even run.

I took a week off and then got back on the treadmill. I reduced from 1200 calories to 800 calories, with no weight gain. From 800 calories to 500 calories, with no weight gain. From 500 calories to 300 calories, again, no weight gain. And I was like what the fuck!

Why was I killing myself in the first place? Was I doing everything wrong?

And thus began my search to find the right diet book and the more I dug the more I realised all books are shit. That is how I arrived at the Obesity Code. This is not a diet book. It is a book that explains obesity. It explains the mechanisms that are at work in your body which convert food into energy and food into fat.

I just happened to have bought Ultra-Processed People quite by accident. But reading these two books together was a revelation. I think both are equally important, dealing with adjacent subjects and very important for everyone to read. Hence I am releasing the two blogs together along with the podcast.

In order to avoid flooding your mailbox, I will stagger this by a day. I hope you learn something new from this.

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I will just summarise the things that I learnt from the book.

The greatest contributor to calorie burn in your body is Basal Metabolic Rate. It burns between 2000 and 3000 calories a day (Unless you are doing hard work in Siberia where you could end up burning up to 5,000 calories a day). Just for reference, if you are running a 10-minute mile, you would have to run for 6 hours to rack up 3000 calories. Exercise helps you workout your body but is not necessarily the main reason you lose weight. It has an important role and you will see that later.

Counting calories alone is not the solution. 1000 calories of broccoli is not equal to 1000 calories of coke. The softer the food, the easier the calorie absorption is. Fluids get absorbed the fastest. Calorie counting in and of itself is useless. What matters is how you get those calories. 1000 Calories of watermelon would be the equivalent of eating 3.5 Kg of watermelon, nearly impossible in one sitting. 1000 Calories of Coke is 2 litres of Coke, you could drink that much in one sitting and still want to eat after that.

All diets have been written out by food companies and as a result today we are in a place where we are advised to have 6 meals a day to lose weight. The only thing this accomplishes is that you end up eating more AND you do not get enough time fasting which allows your insulin level to diminish.

The ONLY thing that contributes to weight increase is the insulin level in your body. Insulin is generated by the pancreas when there is excess glucose in the blood. Insulin converts glucose into fat. Higher insulin results in more glucose being turned into fat.

Once you eat a meal, the body generates insulin. This moves all the excess glucose into fat. If you eat 6 times, the body keeps generating insulin constantly. This disallows the insulin level from falling down.

Resistance -

If you are the kind of person who drinks once a year and you happen to have 5 glasses of wine, you will be drunk. If you have a habit of drinking every day and you have 5 glasses of wine, you might even be able to drive back with that much alcohol in your blood. The more you are subjected to something, you develop a resistance to it. The same goes for insulin. If your body is constantly producing Insulin, the body stops responding to Insulin and you develop Insulin Resistance, hence the glucose in the blood remains high resulting in diabetes.

Cortisol is the stress hormone. This is often generated when you have a fight-or-flight situation when more energy is needed. Cortisol triggers result in fats getting converted to glucose and flooding the bloodstream to power the fight or flight. In the modern world, we neither have to fight nor is there a need for flight when we are stressed. If you are not using up this glucose, Insulin gets produced to convert this glucose back to fat.

High Stress = Cortisol = Blood glucose = Insulin Production = Fat accumulation + Insulin resistance

Lack of sleep, tension, anxiety, essentially all the trappings of our modern world result in high cortisol levels. If you are stressed, go take a jog, at least you will burn the glucose in your blood. This is where exercise plays a critical role, it uses up the glucose stream in your blood and helps regulate the body better.

When you eat food, after a point you produce satiety hormones and you cannot eat anymore. The problem is that the same satiety hormones do not act when the food is ultra-processed Carbohydrates. We have not evolved a hormone for this since this is a recent invention. After you finish eating an entire meal, if I offer you some more vegetables you will not feel like eating at all, but if I offer a dessert no matter how full you will be able to have it! People call it the second stomach, but really, it is food that will fool your satiety hormones.

In the 1950s in the process of vilifying fats, the entire food industry pushed everyone towards carbohydrates. Multi-grain became the ‘in’ thing. This resulted in a shift towards eating more carbohydrates. As a consequence, our food composition shifted towards more and more processed carbohydrates. Everything was fat-free and glucose-heavy.

Glucose is less harmful than Sucrose which is less harmful than Fructose. For the purposes of diabetes, people often look at Glucose content and hence the glycemic index. Most carbohydrates have a high glycemic index. Every fruit has fructose and unlike glucose, it has a low glycemic index which means, it does not translate into high blood sugar immediately.

Fruits also come with a good helping of fibre. This protects from consuming too much fructose. But when consumed as juice or any other such way it is devoid of fibre it is possible for us to consume a huge quantity of it without knowing. This screws with the insulin metabolism and hence causes obesity. Every single fruit juice is bad, cold-pressed or not. The problem also is that the food industry hawks us many foods that are made with high fructose corn syrup as foods with low glycemic index; which is true, but the processed fructose is bad for your health.

He breaks down the three main food groups, Carbohydrates, Proteins and Fats and explains that each has its own merit. The lack of merit arrives from the manner in which it gets served to us.

Carbohydrates are not bad by themselves but grains that we consume today are highly refined. They take grains which have fibre and fat and strip them of both. The fibre makes sure we feel sated. It also takes away from the taste of the food. Fat on the other hand reduces shelf-life. So both are removed, which makes the carbohydrates dangerous to us. We can end up consuming a lot more carbohydrates than our body needs and in a manner where the elements that would balance it out are absent.

Proteins are good for health but should be consumed in moderation. The body has a limited capacity to absorb the nutrients and they also come loaded with animal fats. Legumes and other such plant proteins come with a fair helping of carbohydrates.

Natural fats are good for health contrary to what has been said. Fats from nuts and natural oils which are extracted by non-chemical processes through wood or stone grinding are very good for health. There is a reason the Mediterranean diet involves the lavish use of olive oil and they soak even their breads in olive oil and have it.

Fasting is good for health. The human body has evolved for fasting over long durations. Fasting for a 24-72 hour duration helps boost metabolism and also helps cleanse the body while at the same time using up stores of fat. It definitely does not reduce lean body mass or muscle mass immediately. This is part of the reason every religion has a fasting tradition.