Well, they'd probably make a comparison to weight gain. Once you get off the diet, unless you're living the right kind of lifestyle, you're going to gain the weight back.

Unless you're exercising, having regular social interactions, keeping busy with work that you find meaningful in some way, you're probably going to get depressed once you get off the meds. That's my guess.

They can't, and that's kind of the point. We don't understand the why yet, and are far from discovering the "why not".