Dr. Jason Fung’s book is probably one of the most important you could read regarding your health. It isn’t about a fad diet. He describes what happens to your hormone system when eating various foods as well as the frequency of food consumption. It is easily readable, yet goes into detail about research dispelling long held myths about fat, food, exercise, and calorie control with respect to insulin resistance and weight gain.
The biggest issue with weight-gain is the perception that if you just restricted calorie intake and exercised, you’d lose weight. If you’re not losing weight, it’s because you’re cheating or you’re not trying hard enough. This myth creates some serious cognitive dissonance for people because it’s been told for decades. Its origin is Ancel Keyes’s “Seven Countries Study” from over 60 years ago that was based on correlation, not a controlled causation environment. “Calories” are a nondescript attempt at measuring energy. It does nothing to explain how your body’s hormonal system reacts to the macro makeup of what you ingest.
Basically, your body operates in homeostasis. Energy in = Energy out. It’s why when you exercise, you get hungry. The more you burn, the more you consume. This is not to say that exercise isn’t beneficial on many levels. It just isn’t the deciding factor on weight loss.
Here’s the truth: 70% of your metabolism is hereditary. That leaves you the ability to influence just 30% of how your body handles energy production.
Here’s another truth: Insulin is the sole hormone in your body that controls weight gain. The more insulin produced by your body, the more you gain weight. The more insulin produced, the more resistance receptors will have.
Insulin resistance is a decades long issue. It’s why calorie restriction diets don’t work for long-term weight loss. Eventually you plateau and even can gain weight back from your lowest levels. This is your body working in homeostasis managing the overall energy in = energy out equation. You’re starving yourself and the response is reducing output across the board — muscle loss, temperature reduction, reduced heart pressure, reduced energy and cognition, etc. Once you end calorie restriction, you’ll even gain weight back to above your level before you started your diet so the body has enough fat storage in an attempt to compensate for another starvation event. Specific UCSD and John’s Hopkins studies, among other, show this. You’re only addressing one simplistic aspect of your body’s metabolism.
Long-term reduction in homeostasis weight requires proper insulin function. One key part in addressing this is understanding the macronutrient content of the foods you’re eating. There are 3 macronutrient categories: Carbohydrates, protein, and fat. Refined carbohydrates like sugar, rice, pasta, and bread cause the largest insulin spikes and therefore the most insulin resistance. Fat causes the least insulin response.
There are also processes and hormones that signal satiety, as well as hunger. It just so happens that not only do refined carbohydrates and sugars signal the most insulin production, they also circumvent our body’s satiety signals. It’s why you can be completely full from Thanksgiving dinner but always have room for dessert!
I would consider this book a “working document” on how to live a healthier and potentially longer life for everyone, not just diabetics or people with weight problems. What is unsaid in this book are the details about the metabolic theory of cancer and the mitochondrial processes that are linked to it. Understanding that gives greater weight to the validation of Dr. Fung’s book.