Chapter 17 | Protein

Oct 01, 2019


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

You Will Learn

  • The link between dietary protein and increased insulin. 
  • What is the incretin response?
  • What is the cephalic phase insulin response?


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.

Overview of the Book

Here is the outline of the book. This post covers chapter 17 in Part 5. 

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. 



Chapter 17 was not my favorite in this book. I think Dr. Fung got so focused on trying to explain the little details that he lost the big picture of what this book is about, helping people lose weight for the last time. He got very scientific, in my opinion a bit too much for the lay reader. 

This chapter’s content wasn’t as organized as most, and it was harder to summarize the main points. That being said, I will do my best to break down the takeaway points from this chapter and give you some actionable information to help you reach your weight loss goals.


The Link Between Dietary Protein & Increased Insulin

Dr. Fung makes the point that all foods cause insulin to be secreted. We know there is a link between dietary carbohydrates and insulin release because carbohydrates cause a direct rise in your blood sugar, which in turn requires insulin to be released to move that sugar from your bloodstream into your cells to be used for energy or stored for later use. 

But the actual rise in blood glucose only accounts for part of the insulin response, there are two other important mechanisms that increase your insulin levels, independent of your blood glucose levels.

  1. The incretin effect. 
  2. The cephalic insulin response. 

Insulin, not blood glucose, drives weight gain. So if we want to really lose weight we need to understand all the factors that increase insulin levels. The rise in blood sugar from eating starch or sugar is not the only stimulus for insulin to be released. 


The Incretin Effect

Fats, protein, carbohydrates, even non-caloric artificial sweeteners cause a rise in insulin. But how? Only the glucose from starch and sugar causes a substantial rise in blood sugar levels. Protein and fat don’t have this same effect, but they still cause insulin to be released. It’s important to note that this is a relatively small piece of the weight loss puzzle, but important to understand, especially for troubleshooting weight loss plateaus. 

On page 190, Dr. Fung explains “In 1986, Dr. Michael Nauck noticed something very unusual. A subject’s blood sugar response is identical whether a dose of glucose is given by mouth or intravenously. But, despite the same level of blood sugar, the subject’s insulin levels differ greatly. Remarkably, the insulin response to oral glucose was much more powerful.”

How could this be? The answer is something called the incretin effect, which may be responsible for 50 to 70 percent of the insulin secretion after oral glucose intake. 

Oral glucose from food is far better at stimulating insulin response than injected glucose because when food is ingested, it travels to the stomach and through your digestive tract. Food triggers your stomach and intestines to release two hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (AKA Gastric Inhibitory Peptide or GIP). These are known as incretins. 

“Both GLP-1 and GIP increase insulin release by the pancreas. Fats, amino acids (proteins), and glucose (carbs), all stimulate incretin release and thus, increase insulin levels.” - page 191

The incretins play another important roles, one of which is they delay stomach emptying, thus slowing nutrient absorption. To learn more about incretin hormones, I thought this article was a nice summary. 


The Cephalic Phase Insulin Response

The cephalic phase insulin response is another way your body can increase the insulin response independent of blood glucose levels. This is when your brain triggers insulin to be released in the first few minutes of a meal, even before your blood sugar goes up. In essence, your body is preparing for the rush of blood sugar by having insulin readily available to move the glucose into your cells. (Dhillon et al) ***Cephalic simply means “head”.


Protein Sources: Meat vs Dairy

Dr. Fung briefly touches on some of the research here but I will be doing more research on this topic in the future and likely have more protein posts. I feel like his writing for this section is a little extreme, and he doesn’t provide enough research to convince me one way or the other. For most adults who aren’t getting nearly enough protein, I think either meat or dairy are fine choices. 

He states that vegetable proteins raise insulin levels less than animal proteins, such as whey, but animal proteins lead to a higher level of satiety and may reduce caloric intake after that meal. 

Meat tends to have more of a weight-gaining effect than dairy. One reason may be portions, in that it is easy to consume a large amount of meat, but a little harder to consume a large amount of dairy. 

On page 196, Dr. Fung wrote “The CARDIA study found that the highest intake of dairy is associated with the lowest incidence of obesity and type 2 diabetes.” 

Again, I felt like this chapter was a little short-sighted for my personal preference. I tend to like focusing on how pieces of information fit into the bigger picture.  This chapter seemed to almost villianize protein, especially meat sources. 


Bottom Line

  1. Fact check: Dr. Fung bashed the Atkins diet in this Chapter, stating they recommend a high protein, low-fat diet. Maybe when this book was published in 2016 they did. In my research into the current Atkins diet, they don't advocate for low-fat. In fact, the induction phase (first two weeks) of this diet is a high-protein, high-fat, very low carbohydrate diet with less than 20 grams of net carbs per day. Dr. Fung's point here is that all the protein people on Atkins eat is stimulating their insulin and hindering weight loss. My point is what is that protein replacing in their diet? Maybe they are making better food choices, maybe not. Are they getting their food from the pre-packaged Atkins bars, meals, and shakes, or from real, whole, unprocessed foods. I think there is a place for quick meal replacement options in a crunch, but they shouldn't be a staple. If any weight loss plan or program is suggesting you have to buy their food products or supplements, that should be a red flag. What are you going to do when you don't want to pay for their products anymore? It's not a long-term solution to learning to life a healthy lifestyle and nourish your body. 
  2. Blood glucose is only partially responsible for your insulin levels. The cephalic phase insulin response and incretin hormones also play an important role in your insulin levels, highlighting the importance that all food can cause some insulin release. In my opinion, this is further evidence that eating several times a day is not helpful for losing weight because every time you eat these other mechanisms are triggered to raise your insulin. 
  3. Vegetable protein has a lower effect on insulin levels than animal-based proteins. 



  1. Chapter 17. (2016). In J. Fung, The Obesity Code: Unlocking the Secrets of Weight Loss. Vancouver: Greystone Books. 
  2. Dhillon J, Lee JY, Mattes RD. The cephalic phase insulin response to nutritive and low-calorie sweeteners in solid and beverage form. Physiol Behav. 2017;181:100–109. doi:10.1016/j.physbeh.2017.09.009.
  3. Seino Y, Fukushima M, Yabe D. GIP and GLP-1, the two incretin hormones: Similarities and differences. J Diabetes Investig. 2010;1(1-2):8–23. doi:10.1111/j.2040-1124.2010.00022.x. 

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