The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting

by Jason Fung

As we discussed in Chapter 5, both fasting and bariatric surgery result in a sudden, severe restriction of foods, so it’s not surprising that fasting has a similar effect. In fact, it’s been known to cure type 2 diabetes for over a hundred years. Joslin thought the truth of it was so obvious that studies were not even needed. Interestingly, visceral fat, fat that’s stored in and around the organs, likely plays a large role in type 2 diabetes. It’s more harmful to health and, unfortunately, more common than subcutaneous fat. Fasting and bariatric surgery both preferentially reduce visceral fat. Consider, for example, the effect of wartime starvation on type 2 diabetes. During both World War I and World War II, the mortality rate from type 2 diabetes dropped precipitously. This was due to wartime food rationing, which resulted in a sustained, severe reduction of calories. Figure 6.3 shows the co-occurrence of wartime sugar rationing and a drop in deaths from diabetes, but keep in mind that it wasn’t just sugar that was rationed—almost all foods were restricted, resulting in a sustained, severe calorie reduction similar in magnitude to Fredrick Allen’s infamous starvation diet. Figure 6.3. Diabetes mortality improved during wartime rationing. Source: Cleave, The Saccharine Disease.