The Complete Guide To Fasting

by Jason Fung

The underlying cause of obesity turns out to be a hormonal, rather than a caloric, imbalance.

Both the ketogenic diet (a low-carb, moderate-protein, high-fat diet) and intermittent fasting are excellent methods of reducing high insulin levels.

Excessive insulin causes obesity, and excessive insulin causes insulin resistance, which is the disease known as type 2 diabetes.

being in ketosis teaches your body to burn fat for fuel rather than sugar, and since that’s what your body has to do during fasting, if you’re already in ketosis, your body is already using fuel the way it’s supposed to.

Body fat is composed mostly of triglycerides, which are molecules made of one glycerol backbone to which three fatty acids of varying lengths are attached.

cortisol is also one of the major drivers of obesity. In fact, synthetic cortisol, a medication called prednisone, consistently causes weight gain, particularly in the trunk.

Type 2 diabetes was quite uncommon until the twentieth century, for two reasons: first, it is typically diagnosed after age fifty (in fact, it used to be called adult-onset diabetes) and average life expectancy was lower than it is today, and second, food was not nearly as available and plentiful.

Fast-forward to 2016, and there are more Americans with prediabetes and diabetes than without: in 2012, 14.3 percent of American adults had diabetes and 38 percent had prediabetes, for a total of 52.3 percent.

It’s also helpful to avoid artificial sweeteners. Even though they contain no calories, they may still kick off the cephalic phase response, stimulating hunger as well as insulin production. I don’t recommend artificial sweeteners during fasting for this very reason.

artificial sweeteners can kick off the cephalic phase response, triggering hunger and insulin production, so I recommend avoiding them during a fast.

The secret is to understand that hunger comes in waves. You just need to ride out the waves.

We also permit a small amount of cream or coconut oil to be added to coffee or tea.

So the optimal strategy seems to be eating the largest meal in the midday, sometime between noon and 3:00 p.m., and only a small amount in the evening hours.