“People can go on a fast and think that it is going to be healthy for them, and it may in fact be, but then they’ll come off and they’ll binge for three weeks,” she says.
I think a three week binge is fairly likely--if we're talking about extended fasting. Or if fasting is used in addition to a semi-starvation diet rather than instead of a semi-starvation diet. Or if the food eaten when you're not fasting is of the wrong sort. I ate Atkins, my weight went down. My appetite naturally decreased, and I became spontaneously more active. Also intentionally more active, but I'll call that spontaneous as well. If you always intended to walk 3 miles a day, but only found the energy to do so once on a ketogenic diet--it may be a structured exercise program, but now you're not fighting against your natural inclination.
So I lost weight. So what happens when you're 30 pounds down--because a change in diet effectively decreased your setpoint by that much--and then you go back to the SAD? Suddenly you're lazier, you're hungrier. You binge. Go on a less insulinogenic food plan between fasts, while eating sufficient food, and things might be a bit different.
Problem with fasting--even though appetite might decrease while you're on it--Seth Roberts of the Shangri-La diet fame postulated fasting as one thing that might decrease your body weight set point, and this might explain why people with sufficient body fat often experience lack of hunger during fasting--if your appetite largely depends on what you've recently eaten, go back to SAD between fasts, and suddenly your body acts as if it's starving, and you binge.
I discovered the benefit of a more ketogenic, higher fat diet after using higher protein, more 'moderate' fat to lean out a few years ago. Moderate goes in quotes because my response to this approach wasn't moderate, it resulted in binges, including carbohydrate binges--something very rare in my then already more than a decade of faithful low carb eating. Going to an 'extreme' ketogenic diet stopped the binges in their tracks. Protein, supposedly the most 'satiating' of the macronutrients, totally failed me once my body fat was below a certain level.
If I wanted to go on a three week binge, all I'd have to do is go back to the SAD for three weeks, and I'm not even fasting much these days. That would hardly invalidate what I've been doing up to this point.
Intuitive eating. There's these baby birds that will respond to a red spot on their mother's beak. Paint an exaggeration of the spot on a wooden stick, and they'll respond to that--instinctively, respond to it more strongly than they do to their mother. There's also a male beetle in Australia that prefers stubby beer bottles to the females of its own species. Intuitive eating works when the environment isn't designed to hijack your natural instincts. That ain't us.