{"id":4049,"date":"2026-06-13T06:29:43","date_gmt":"2026-06-13T14:29:43","guid":{"rendered":"https:\/\/www.nehrlich.com\/blog\/?p=4049"},"modified":"2026-06-13T06:30:04","modified_gmt":"2026-06-13T14:30:04","slug":"the-obesity-code-by-dr-jason-fung","status":"publish","type":"post","link":"https:\/\/www.nehrlich.com\/blog\/2026\/06\/13\/the-obesity-code-by-dr-jason-fung\/","title":{"rendered":"The Obesity Code, by Dr. Jason Fung"},"content":{"rendered":"

Amazon link<\/a><\/p>\n

Disclaimer: I have not independently verified any of the scientific claims below. This may be pseudoscience, but it sounded convincing to me.<\/i><\/p>\n

I had always believed that body weight was a function of calories in and calories out, but Dr. Jason Fung’s book The Obesity Code<\/i> convinced me that was too simplistic. He explained how the human body was designed to survive periods of famine and inconsistent food supply (it was hard and uncertain work to hunt animals!) by kicking into energy saving mode, slowing down bodily functions where there are less calories available. When there are excess calories, the body stores them away as fat to be accessed the next time calories are unavailable. <\/p>\n

This biological process is called homeostasis, where the body is designed as a system<\/a> that will return to its current “set point”, much like a thermostat in a house that turns on the furnace when the house gets too cold, or turns on the air conditioning when the house gets too hot. This is also true of our happiness, where people tend to have a baseline level of happiness that they will return to after shocks, both positive (winning the lottery) or negative (experiencing death or sickness). Homeostasis explains why it’s so hard to change weight, because our body adjusts biological processes to burn more or less energy to return to its “set point”. <\/p>\n

Fung claims that insulin is the hormone that regulates the set point for our weight, because it “facilitates the uptake of glucose into cells for energy”. When we eat, carbohydrates are converted into glucose circulating in the bloodstream, and insulin is released from the pancreas to move the glucose into storage for later use, some of it going to glycogen in the liver for immediate use, the rest going towards creating fat. But when insulin levels are higher, the set point increases and the body will “increase fat mass to reach the desired body set weight”. This becomes a problem because “Available calories are diverted to increase fat, leaving the body short of energy (calories). The body’s rational response is to try to get more calories. It increases the hormonal signals of hunger … and metabolism slows to conserve calories needed for fat growth by shutting down other functions.” In other words, more insulin leads to higher obesity, because insulin diverts more of the calories we ingest into fat storage, and the body tries to get more calories to make up the difference. <\/p>\n

So how does insulin relate to the nationwide trend towards obesity? Fung identifies two factors: 1) we are eating more processed food with more sugar\/corn syrup\/sweeteners and 2) we are eating more often. <\/p>\n

Both of these lead to higher glucose levels in the bloodstream, because 1) more glucose is being ingested and 2) constant snacking means the body isn’t able to process glucose out of the bloodstream before the glucose is elevated again. The result is that our body releases more insulin to try to bring the glucose levels back down, but it doesn’t work because of the constant intake of more food\/glucose. Thus, the higher insulin becomes normal and the body weight set point increases, facilitating fat creation. <\/p>\n

Even worse, the higher levels of insulin leads to cells developing insulin resistance, where they need more insulin to get the same results, similar to how the more coffee you consume, the more coffee you need to get to the same level of alertness. But if glucose levels persist, the body releases yet more insulin, which creates more insulin resistance and higher insulin levels in the bloodstream, increasing the body weight set point. This creates a vicious cycle over time where higher insulin resistance leads to higher levels of glucose in the bloodstream (because insulin is less effective), which triggers the release of more insulin, which leads to higher insulin resistance, and around we go again. <\/p>\n

This insulin resistance cycle can lead to what is called metabolic syndrome, a precursor for heart disease, strokes and diabetes, characterized by elevated blood sugar after fasting (high glucose levels), high blood pressure, large waistline (fat accumulation), elevated triglycerides and low HDL (“good”) cholesterol. In other words, if you want to reduce your chances of strokes, heart attacks and diabetes later in life, you need to avoid insulin resistance. <\/p>\n

So how do you interrupt or reverse the insulin resistance cycle? Lower the glucose levels in the bloodstream by reversing the two obesity factors I listed above: 1) eat more natural foods, especially less simple carbohydrates which result in glucose spikes in the bloodstream, and 2) eat less often. Fung and others recommend intermittent fasting, either by regularly fasting for a day, or by restricting the hours in which one eats. For instance, one recommended routine is 16\/8, fasting for 16 hours, and eating only in an 8-hour window each day e.g. from 10am to 6pm. <\/p>\n

The guiding principle here is that managing your weight is about reducing glucose levels to manage insulin release, not about eating less or exercising more. <\/p>\n

I had wondered why I didn’t manage to lose weight when I was exercising 15+ hours a week, including long bike rides, doubles volleyball games and ultimate frisbee. But I hadn’t changed my diet and in fact, ate more carbs, figuring that I could eat more calories since I was exercising so much. That diet meant that I was on the verge of metabolic syndrome with borderline high numbers across 4 out of 5 indicators; in particular, I likely had insulin resistance since my fasting blood sugar levels were high. After reading Fung’s book, I realized that was because in addition to eating lots of carbs, one of my vices had been drinking a lot of soda, so my bloodstream was constantly elevated with glucose. <\/p>\n

After reading this book and Peter Attia’s Outlive<\/i><\/a>, I changed my diet by addressing the obesity factors listed above: 1) eating less carbs and more natural foods (and mostly eliminating soda and carb-based snacks like chips and candy) (the Glucose Goddess tips on reducing glucose spikes<\/a> were helpful), and 2) eating less often, especially no late-night snacks, aiming for 13\/11 intermittent fasting most days, eating breakfast at 8am and dinner by 7pm. <\/p>\n

And that diet change made a difference. In the first couple months after changing my diet, I lost 10 pounds and my body fat percentage went down by 4% even though I didn’t exercise more – I had managed to reset my body weight set point to a lower number. In the two years since then, I have lost a few more pounds and my body fat percentage has continued to decrease (now at 15%), so this was not a fad diet where I quickly gained the weight back – this has been a sustainable change to my body composition. <\/p>\n

Fung’s book was helpful to help me learn more about the science of how the body manages fat and weight. But unless you really want to understand the hormonal mechanisms and see the citations, you can probably skip the book and just follow the advice above or Tim Ferriss’s Slow Carb diet<\/A> to get similar results. <\/p>\n","protected":false},"excerpt":{"rendered":"

Amazon link Disclaimer: I have not independently verified any of the scientific claims below. This may be pseudoscience, but it sounded convincing to me. I had always believed that body weight was a function of calories in and calories out, but Dr. Jason Fung’s book The Obesity Code convinced me that was too simplistic. He […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[59,3],"tags":[],"class_list":["post-4049","post","type-post","status-publish","format-standard","hentry","category-health","category-nonfiction"],"_links":{"self":[{"href":"https:\/\/www.nehrlich.com\/blog\/wp-json\/wp\/v2\/posts\/4049","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.nehrlich.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.nehrlich.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.nehrlich.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.nehrlich.com\/blog\/wp-json\/wp\/v2\/comments?post=4049"}],"version-history":[{"count":12,"href":"https:\/\/www.nehrlich.com\/blog\/wp-json\/wp\/v2\/posts\/4049\/revisions"}],"predecessor-version":[{"id":4061,"href":"https:\/\/www.nehrlich.com\/blog\/wp-json\/wp\/v2\/posts\/4049\/revisions\/4061"}],"wp:attachment":[{"href":"https:\/\/www.nehrlich.com\/blog\/wp-json\/wp\/v2\/media?parent=4049"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.nehrlich.com\/blog\/wp-json\/wp\/v2\/categories?post=4049"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.nehrlich.com\/blog\/wp-json\/wp\/v2\/tags?post=4049"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}