Since I'm a fiction writer, not a food writer, someone else is welcome to this idea: "How a Thin Person Eats". It would be kind of a diet book, but instead of focusing on how heavy people lose weight, it would focus on how lighter people maintain their lighter weight.
I have my doubts about the current thinking around weight. There's a lot of judging and shame around fatness, which I hate. I don't think everyone should have to be thin. I would like people to feel good about themselves at whatever size they're at, and choose their foods and exercises based on what they love.
For people who have fat they want to shed, I think there's too much focus on restrictive, uncomfortable diets that might get results in the short term but are horribly hard to translate into long-term habits.
I am a thin person, and my body composition is very healthy (plenty of muscle, sturdy bones). I have never dieted or restricted my food choices. Depending on what you believe about diet science, this could mean I have a wickedly high metabolism, or I get tons of exercise, or it could mean I have accidentally hit on a sustainable diet which doesn't lead to weight gain.
So I wonder--how do other thin people eat? What are the habits we share which are healthy and could be adopted by someone who wants to become sustainably thinner?