> Too often, the term "natural" is used to imply that something is healthy.

Of course.

Your concerns, particularly the ones about the body's metabolism and absorption of vitamins, are all addressed in the Herbalife literature. They're about two steps ahead of you. This isn't some cheapie wonder diet that some nutritionist made up as a graduate thesis. The literature on it, which is more hard science than sales pitch, is extensive. I recommend you read the literature before raising questions here that are already answered.

> The best diet plan is to exercise in proportion to your calorie intake and eat a variety of foods. Candy bars and potato chips are perfectly fine if you compensate for them.

This is true. It's also idealistic to the point of uselessness for a great many people. Some people are genetically predisposed to gain weight beyond what is healthy, even when considering what most people consider a healthy weight is much thinner than what is actually optimal. Plus, the Herbalife diet supplements this "common sense" diet of moderation rather than replaces it. There are no frivolous restrictions such as "eat this particular food" and "don't ever eat this particular food." It's a formalized guide to enforce moderation with tablets to supplement that (so you get all the right vitamins and other nourishments no matter what).