This is a carry-on thread from a thread on all things Fung and diabetes, we just went with this name because his book came out. We have another thread specifically for intermittent fasting, but it's proven wildly unpopular, everybody just ended up defaulting to here. I think having a personality like Dr. Fung has kept this intermittent fasting related thread alive where others have eventually faded.



Good question... I was thinking about one kind of intermittent fasting the other day. You could eat 500 calories less every day, or just skip eating one day a week--either way, you're eating 3500 calories less a week. But in one case, 6 out of 7 days of the week--nothing has changed. It seems plausible that the chronic calorie restriction, while seemingly milder, could cause more of a stress on the system, and more of a metabolic slowdown.

When you talk about 600-800 calories--once calories are that low, things are a bit different. Fasting vs. eating to appetite could be looked at as a continuum. Eat nothing, and if you have enough fat to spare, very often there'll be appetite suppression after a day or two. In very low calorie diet studies, the same thing happens--people eat 600 or 800 calories a day, and after a few days, there's an appetite suppression. I think it's probably true that there's a certain threshold, where insulin is low enough for this appetite suppression to kick in. Dr. Fung talks about daily calories with bariatric surgery being forced down low enough that the people are basically forced into a kind of fast.

Some people will go on a low carb diet, and that's enough--they'll end up eating the same 1500 calories they'd have eaten on a semi-starvation diet, except that there's no intentional decrease in calories, they're just satisfied with less--and feel as energetic as ever, or more so. The difference might be that at that calorie level, low carb just brought their insulin levels a lot lower.