There is so much contradictory information about weight gain and diet out there. Whoever finds the "golden egg" answer
will certainly be a multi-billionaire and that hasn't happened yet.

But I do think we should listen to our bodies and see what they tell us.

If you follow some eating plan that makes you hungry all time, or is unrealistic in some way, and your body speaks up, then that has to change.

The players so far are leptin, ghrelin, insulin, and glucagon.

Leptin in particular looked really good, but now they are saying there is "leptin resistance" and that changes how people perceive hunger. So leptin as a "diet aid" has not appeared for humans.

Wiki has interesting things to say about all 4 of these hormones.

I'll recommend Dr. Gittleman's book again... Your Body Knows Best. It explains why some people cannot go vegetarian safely, why some people require dairy, why carbs are devastating to some people and not others, etc. The beginning of the book details Dr. Gittleman's own journey thru unsatisfactory eating styles which she "thought" would be good for her. She learned otherwise, and looked at the research and found some answers.
It is very readable, and untechnical, and compelling.