There are a number of theories out there of why we have become obese and diabetic. Some blame it on saturated fat; some on sugar; some on excess calories; some on vegetable oils; some on lack of discipline and sedentary lifestyle.
Dr. Fung is in the camp of “excessive levels of Insulin lead to diabetes”. While carbs do cause insulin to rise, many cultures have a starch-based diet, but never developed diabetes or obesity.
Maybe it had to do with food culture (no snacking, family meals, religious observation of fasting, such as Ramadan).
Whatever the cause of excess insulin, the most effective way to lower insulin is through fasting. And humans were designed to fast. We developed fat stores, and the ability to create ketones from fat and glucose, so that we could go long periods of time without eating.
When Insulin goes low enough, our fat cells release their fat contents into the bloodstream so that other tissues in the body can use fat and ketones for energy. When Insulin levels are high, the fat cells are unable to release their contents, and other tissues go hungry because they don’t have enough energy to function, unless we are frequently eating.