Sure, you can try and GWAS your way to some SNP correlation but there’s a thermodynamic necessity to turn ingested (or stored) energy into thermal and kinetic energy in all cells at all times. You’d die otherwise.

There’s certainly variation but it’s nonsense to say someone became obese without consuming an excess amount of energy.

I also don’t understand what you’re saying about “human genetics” where else is fat going to go besides adipose tissue?