Chapter 5: The Overfeeding Paradox

Jul 12, 2019


Click here to watch a replay of the Facebook LIVE discussion. 

You Will Learn

  • What is the overfeeding paradox?  
  • What is your body set weight?  
  • What is leptin’s role in obesity?  


About Dr. Fung, Author of The Obesity Code and The Diabetes Code

Dr. Jason Fung is a medical doctor, nephrologist by trade, who specializes in kidney disease, type 2 diabetes, and obesity. He acknowledged that traditional medicine wastes time and resources attempting to treat symptoms of disease, rather than the cause of disease.  

You can purchase The Obesity Code book HERE. Most information in this post is direct from this book. 


Overview of the Book

Here is an outline of the book. Today I’m covering Chapter 5 in Part 2 of the book. 

  • Part 1: “The Epidemic,” explores the timeline of the obesity epidemic and the contribution of the patient’s family history. It highlights the underlying causes of obesity. 
  • Part 2: “The Calorie Deception,” reviews the current caloric theory in depth and highlights the shortcomings of the current understanding of obesity. 
  • Part 3: “A New Model of Obesity,” describes how hormones are involved in the development of obesity. These chapters explain the central role of insulin in regulating body weight and describe the vitally important role of insulin resistance. 
  • Part 4: “The Social Phenomenon of Obesity,” dives into childhood obesity and why obesity is associated with poverty. 
  • Part 5: “What’s Wrong with Our Diet?,” explores the role of fat, protein, and carbohydrates, the three macronutrients, in weight gain. In addition, it examines one of the main culprits in weight gain - fructose - and the effects of artificial sweeteners. 
  • Part 6: “The Solution,” provides guidelines for lasting treatment of obesity by addressing the hormonal imbalance of high blood insulin through proper nutrition, sleep, and stress management. 


What is the Overfeeding Paradox? 

The overfeeding paradox is that excess calories alone are not sufficient for weight gain. This is another hole in the theory that in order to lose weight we need to eat less and exercise more.  

Dr. Fung discusses several research projects that prove our bodies are not a scale, balancing calories in and calories out.  

In one example, a man did two experiments eating 5793 calories per day for 21 days. In the first experiment, these calories came from a low-carbohydrate, high fat whole food diet. His diet was comprised of 10% carbohydrates, 53% fat, and 37% protein.  

According to the calorie math, he was supposed to gain 16 pounds. But he actually only gained 2.8 pounds and lost over an inch from his waist. So he did gain a little weight but not nearly what was to be expected, and the weight he gained was lean mass.  

For his second 21-day experiment, his 5793 calories per day diet came from a traditional American diet high in processed foods and refined carbohydrates, with a macronutrient breakdown similar to the U.S. dietary guidelines. His diet was comprised of 64% carbohydrates, 22% fat, and 14% protein. This go around he actually did gain the weight. He gained 15.6 pounds and his waist circumference increased by 3.6 just 21 days!  

This experiment proved that your weight and waistline depend much more on the quality, not just the quantity of calories in your diet.  

While there is so much emphasis on losing weight, I’d argue that gaining healthy, lean muscle mass is hard, too and is a specialty area in and of itself.  

I can attest to this. After I had my son I was eating a TON to keep up a good breast milk supply for him. I would estimate that I was eating around 4,000 calories per day and drinking a ton of fluid. At my height I was producing about 800 calories of milk for him per day. My body weight continued to go down until I had reached my pre-pregnancy weight.  

This takes us into the next point covered in this book...your body set weight. 


What is the Body Set Weight? 

Your body set weight is the weight that your body wants to be, the weight you normally are when you are not trying to lose weight. Think of your house thermostat set at 70 degrees. That is your home’s set point.  

It is possible to temporarily eat more or less to lose or gain weight, just like your house temperature may go up or down a couple of degrees.  

But soon enough your body will start to compensate, just like your heating and air conditioning, to return your weight back to the set point.  

When we eat fewer calories consistently, we may lose weight temporarily but your body makes adjustments to ensure that your weight returns to its set-point. Here are a few main changes:

  • Your metabolism slows down, burning less calories. 
  • Your hunger hormones increase, making you want to eat more. 
  • Your satiety (fullness) hormones decrease, making you want to eat more.  

The key to lasting weight loss is lowering this set-point, not simply eating less calories.  

The best science available states that your body’s set point is in you hypothalamus region of your brain. It is influenced by hormones. Research into the body set weight led researchers to discover a hormone called leptin. 


What is Leptin’s Role in Obesity? 

Leptin is a protein produced by fat cells. Leptin plays a role in appetite regulation and fat storage. 

Higher levels of leptin indicate we have enough fat and decrease our appetite.

Lower levels of leptin indicate we don’t have enough fat and increase our appetite.  

Rare human deficiencies in leptin were found, causing massive weight gain. When manufactured leptin was given to that person (similar to type 1 diabetes injecting insulin), their weight came off. So clearly leptin did play a role in weight regulation. The next test was to see if administering leptin in cases of common human obesity (i.e. people that were not leptin deficient) would also help reduce their obesity.  

The short answer is no, increasing leptin in obese individuals did not result in weight loss. Future research has revealed that the vast majority of people with obesity are not deficient in leptin. Their leptin levels are actually high, not low.  

They have a lot of body fat. This fat produces a lot of leptin. After time, your body becomes accustomed to these high levels and resistant to them, meaning the signaling doesn’t work and your body thinks it doesn’t have enough leptin. So it acts accordingly. 

When your body doesn’t think it has enough leptin it essentially thinks it's starving so your body adjusts by: 

  • Increasing your appetite causing you to eat more.
  • Lowers your metabolism causing your body to burn fewer calories.  

Leptin is a factor in the body set point, but Dr. Fung points out that if fails the causality test. Giving leptin doesn’t make people thin. I’ll discuss Dr. Fung’s hypothesis on what hormone is most important in lower your body set-point in the upcoming couple of weeks.  


Bottom Line 

  • Eating more calories doesn’t necessarily mean you will gain weight. 
  • Your body has a set weight that is influenced by hormones. 
  • Leptin is one of the hormones that help regulate appetite and fat storage. People with obesity have leptin resistance, meaning there is a lot circulating but your brain still thinks it's starving, leading to increased appetite and fat storage.

If you have ever felt like no matter how hard you try you just cannot lose weight, or you get to a certain weight and cannot get any lower, even though it would be healthy for you to do-so you can probably relate to this information. Your body’s set weight is too high and we have to figure out how to lower that.  

Clearly losing weight is not as simple as the “eat less, exercise more” philosophy would have us believe. That leads us to focus on calories, and the research discussed in this chapter proves that hormones, not calories, are much more important to our set point, which is the ultimate thing we need to focus on for lasting weight loss...lowering that set point.  



1. Chapter 5. (2016). In J. Fung, The Obesity Code: Unlocking the Secrets of Weight Loss. Vancouver: Greystone Books. 

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