Review and Summary: The Diabetes Code

The Diabetes Code Book Cover

Initially, I was deeply impressed with how Jason Fung presented the complexities of obesity in The Obesity Code, which piqued my curiosity to go into another one of his works, The Diabetes Code. Given his background as a specialist physician, researcher, and best-selling author of science-based books, I firmly believe that exploring diabetes through his expertise would be a valuable investment of my time. And, yes, The Diabetes Code was undeniably worth my time.

This book claims that type 2 diabetes is primarily caused by excessive sugar consumption. Therefore, the proposed solutions involve reducing sugar intake and burning off the excess sugar. These are not a secret, and most of us understand these findings. Fung’s main argument throughout the book centers on the possibility of treating type 2 diabetes without medication, focusing on two approaches: diet and intermittent fasting—not by taking insulin—a suggestion that some of us find controversial. The Diabetes Code provides a comprehensive explanation of how our food choices contribute to the development of fatty liver, cell clogging, and ultimately insulin resistance.

If the situation is getting worse, then the only logical explanation is that our understanding and treatment of type 2 diabetes is fundamentally flawed.

Jason Fung, The Diabetes Code.


Diabetes is reversible and preventable without medication

  • Only diet and lifestyle changes—not medications—will reverse diabetes.
  • Most important: weight loss
  • Most of the medications used to treat type 2 diabetes do not cause weight loss. For example, insulin is notorious for causing weight gain.

Two ways to reverse and prevent type 2 diabetes

  1. Put less sugar in.
  2. Burn off remaining sugar

How does too much sugar cause type 2 diabetes?

Eat sugar → body secretes insulin to help move the sugar into your cells, whether it’s used for energy. If you don’t burn off that sugar sufficiently, then over decades your cells become completely filled and cannot handle any more. The next time you eat sugar, insulin cannot force any more of it into your overflowing cells, so it spills out into the blood. Sugar travels in your blood in a form of glucose, and having too much of it—known as high blood sugar—is a primary symptom of type 2 diabetes.

All the conditions we thought were problems—obesity, insulin resistance, and beta cell dysfunction—are actually the body’s solutions to a single root cause—too much sugar.

Jason Fung, The Diabetes Code.

Excessive insulin drives fat accumulation and obesity.

If our feeding periods predominate over our fasting periods, then the ensuing insulin dominance leads to fat accumulation. Too much insulin signals the liver to keep admitting glucose, resulting in more production of new fat via de novo lipogenesis. Normally, if periods of high insulin (feeding) alternate with periods of low insulin (fasting), weight remains stable. If high insulin persists, the body receives the constant signal to store food energy as body fat.

Insulin is not the answer for type 2 diabetes.

The glucotoxicity paradigm

  • Heavy-handed dosing of insulin to reduce blood glucose had produced all the problems of excessive insulin: obesity, metabolic syndrome, and atherosclerosis. Despite these side effects, intensive insulin dosing was worth the risk for the proven cardiovascular benefits, but only for type 1 diabetes.

In either type 1 diabetes and type 2 diabetes, if you continually raise the dosage of insulin to lower blood glucose, you simply trade higher insulin toxicity for less glucotoxicity. And over time, insulin toxicity becomes the key determinant for survival because it leads to [[metabolic syndrome]] and its sequelae, cardiovascular diseases and cancer. Thus, the optimal treatment strategy reduces both blood glucose and insulin simultaneously.

Diabetes’ medications that are weight neutral.

  • Metformin
  • Dipeptidyl peptidase-4 (DPP-4) inhibitors
    • lower blood glucose by blocking the breakdown of incretins, which are hormones released in the stomach that increase insulin secretion in response to food.
    • High incretin → stimulate insulin release; however, this insulin response is not sustained and therefore these drugs do not cause weight gain.
    • Low risk of hypoglycemia
    • Effectively lowered blood glucose but did not reduce risk of heart attacks or stroke.

Diabetes’ medications that cause weight loss

Sodium-glucose cotransporter 2 (SGLT2) inhibitors

  • Block glucose reabsorption in the kidneys → allowing glucose to escape in the urine, which replicates the protective mechanisms used by the body during severe hyperglycemia.
  • By the excretion of glucose outside the body → lower blood glucose, but also lower body weight, blood pressure, and markers of arterial stiffness.
  • Reduced the risk of death by 38%.
  • Reduced the risk of progression of kidney disease by almost 40%.
  • Lowered both insulin and glucotoxicity
  • Most noticeable side benefits: weight loss
  • Main side effects: increased risk of urinary tract infections due to increased urinary glucose concentration

Alpha-glucosidase inhibitors

  • Blocks the enzyme alpha-glucosidase and alpha-amylase, both of which are required for proper digestion of carbohydrates → prevents complex carbohydrate, which are chains of glucose, from breaking into smaller glucose molecules → reducing absorption.
  • Equivalent to low-carb diet.
  • Reduces both glucotoxicity and insulin toxicity.
  • Its blood glucose-lowering effect is less powerful and bloathing is a bothersome side effect.

Glucagon-like Peptide-1 (GLP-1)

  • Mimic the effect of the incretin hormones
  • Normally, the incretins secreted by the stomach have several physiological roles when you eat food. They increase the release of insulin but also slow down the motility of the stomach and increases satiety.
  • The blood glucose-lowering effect was fairly modest but the cardiovascular benefits were not

Low-calorie diets are not the answer.

  • Physical inactivity is an independent risk factor for more than 25 chronic diseases, including type 2 diabetes and cardiovascular diseases.
  • The benefits of exercise and resistance exercise far beyond simple weight loss.
  • Yet results of both aerobic exercise and resistance exercise studies in type 2 diabetes are varied.
  • The main problem has always been noncompliance.
  • The biggest issue is lack of visible results.

The disappointing impact of exercise

  • All exercise programs produce substantially fewer benefits than expected. There are 2 main reasons:
    • Exercise is known to stimulate appetite
    • A formal exercise program tends to decrease non-exercise activity
  • In the end, the main problem is that type 2 diabetes is not caused by lack of exercise. The underlying problem is excessive dietary glucose and fructose causing hyperinsulinemia. Exercise can only improve insulin resistance of the muscle. it does not improve insulin resistance in the liver at all.

Three rules for reversing type 2 diabetes

1. Avoid Fructose

  • In sucrose (table sugar) and high-fructose corn syrup.
  • Eliminate sugar-sweetened beverages.
  • No chemical difference between the fructose contained naturally in the fruit and the fructose contained within sucrose → avoid eating excessive amounts of fruit, especially as many modern varieties are now available year-round and have been bred to be sweeter than in the past.
  • Dried fruits are usually high in sugar → avoid raisins, dried cranberries, fruit leathers and the like.

2. Reduced refined carbohydrates and enjoy natural fats

  • Reduce or avoid refined wheat products, such as bread, pasta, waffle, etc.
  • Limit processed corn products, such as pop corn, corn ships, and tortillas, and refined potato products
  • Eat white rice in small amounts
  • Replace them with fatty fish, olive oil, avocados, and nuts. The natural saturated fats found in beef, pork, bacon, butter, cream, and coconuts are also healthy fats. Eggs are an excellent choice, as are most seafoods.
  • Not all fats are benigns. The industrially processed, highly refined seed oils that are high in omega-6 fat are not recommended
    • Because they can cause inflammation and adversely affect human health.
    • These oils include sunflower, corn, canola, sunflower, and vegetable oils
    • Do not use these vegetables oils at high heat because they release harmful chemicals called [[aldehydes]] when heated
  • Recommended diet: The Low Carb, High Fat or Low Carb, Healthy Fat (LCHF) diet

3. Eat real food

Rule number 4, in case the first three are not enough:

4. Fasting

  • Restricting calories → compensatory increase in hunger and a decrease in the body’s metabolic rate → this effect derails weight loss efforts and ultimately ends in failure.
  • Intermittent fasting succeeds because it produce beneficial hormonal changes that chronic caloric deprivation does not. Most importantly, it reduces insulin and insulin resistance.
  • The secret to long-term weight loss is to maintain basal metabolism.
    • Fasting → triggers numerous hormonal adaptations that do not happen with simple caloric reduction:
      • Insulin drops sharply → preventing insulin resistance.
      • Noradrenaline rises → keeping metabolism high.
      • Growth hormone rises → maintaining lean mass.
    • Fasting works because it keeps basal metabolism high because it is a survival mechanism. During fasting:
      • The body opens up its ample supply of stored food—body fat. Basal metabolism stays high, and instead of using food as our fuel, we use food our bodies have stored as body fat.
      • We first burn glycogen stored in the liver. When that is finished, we use body fat. And since there is plenty of fuel, there is no reason for basal metabolism to drop.

Which one is better: fasting or low-carb diet?

The very low-carb diet does remarkably well, giving 71% of the benefits of the fasting without actual fasting.

Fasting for type 2 diabetes

More intensive fasting will give quicker results, but if you have had type 2 diabetes for 20 years, it is unlikely to reverse in several months. It will take longer, though the exact time differs from patient to patient.

Fasting when taking medications

  • If you’re taking medications: monitor blood glucose frequently with a standard home monitor at least 2x a day and ideally up to 4x a day.
  • If you’re unsure to take medication or not: it is generally better to use less medication during fasting. If blood glucose rises too high, you can always take more medications to compensate. However, if you overmedicate and hypoglycemia develops, you must eat some sugar to treat it. That will break the fast and is counterproductive to reversing the diabetes. Again, consult with your doctor for guidance.

Author: Jason Fung

Publication date: 2 April 2018

Number of pages: 246 pages


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