People with low BMI aren’t more active, they are just less hungry and “run hotter”

Naturally higher functioning metabolisms. Your metabolism isn’t something you can really nurture.

The best analogy is energy efficiency. Low BMI humans are less energy efficient, meaning it costs more energy to run the human. I’m one of those; if I’m exercising, I lose weight on 3800 daily calories.

Some people are more or less energy efficient. This probably generally correlates with hunger over a broad scale (as the research is implying) but other things correlate with hunger too, such as dietary choices (do you choose to eat clean/poor), types of food you eat, eating regimen, digestion, etc.

What may be hungry to you may be miserable to me. There’s absolutely a genetic component to hunger, however the energy efficiency of a human is more impactful, because hunger can be easily mitigated by lifestyle choices.

Anecdotally; I’ve never been a big eater. Most of the larger people I know snack constantly. Alternatively, from an athletic perspective, people that are less energy efficient, meaning they gain weight on less food, can manipulate their bodies much more easily than someone like me.

/r/science Thread Parent Link - eurekalert.org