DD, there ARE people who can do well on other WOE's. But once you have become carb sensitive, or if you are dealing with a poorly or non functioning pancreas, LCHF is really, with or without IF, is really the only rational way to do it.

I am an Herbalife distributor. I have seen people lose literally hundreds of pounds, following their "two shakes and one colorful meal" plan.

And, I've seen people lose down to maybe 180, 190, 210, and then stop. Because the number of carbs in that plan are too high for them.

I'm one of them. I couldn't get below 184, with three years of careful eating.

So, I understand your confusion. But IF you add one piece to your understanding of Dr. Fung's hypothesis: the development of insulin resistance and carb sensitivity, it will make sense for you.

Once we've developed those two, related issues, we can no longer lose easily, or enough, on a diet that is even fairly low carb.

As for the diet and exercise equation: many people lose weight on low cal, but it's not sustainable, because there is too much hunger created by the rising and falling levels of BGs.

Ask any person who went on a long term low calorie diet, and hunger will be their overriding impression of that period of their lives. THAT is why diet and exercise don't work, in the long run, for most people.