Does peace of mind make someone gain weight?

Not directly.

Peace of mind doesn't automatically make you gain weight, but it can make healthy weight gain easier.

When you're constantly stressed or worried, your appetite may reduce, you may skip meals, or your body may not function at its best. But when you're relaxed and less stressed, you're more likely to eat well, sleep better, and stay consistent with healthy habits.

So, peace of mind alone won't make you gain weight. It simply creates a better environment for your body to respond to proper nutrition.