fat people at my work have 10,000 calories in their desk drawer at all times.
I eat 1-2 unhealthy meals a day and 1 healthy meal prepared by my wife.
But I don't eat and drink another 2,000 calories of junk in between. You don't have to starve yourself to be a reasonable weight.
You just don't have to eat all day long.
I have 3 overweight siblings. They think I have better genes. But they eat twice as many calories as me every time we eat out. Everything is dipped in ranch, and they drink regular soda. That is an extra 500 calories at one meal. I eat 2 breadsticks and they eat 6.
I guess the gene could be that I have some self-control. Part of that self-control is not wanting to live with constant heart burn and sleep apnea.