I have read on multiple sites that sugar causes fat gain especially in the belly area. But isnt fat distribution mainly determined by your genes? I know that sugar spikes insulin but does that mean that excess calories will be stored in the belly because of insulin spike? Let’s say that someone eats balanced all day then later they would eat something with added sugar in it that exceeds their calorie maintenance by 300 cal. They would obviously gain fat since they ate more calories that they burn but would those calories store in the belly just because of the sugar in it?
It depends on your current build. People with high body fat tend to have high insulin resistance, which causes blood sugar to be stored as body fat instead of glycogen stored in the liver and in the muscle tissue. More fit people tend to use their glycogen stores more regularly, leading them to have a much lower insulin resistance. In this case, blood sugar is used to rebuild muscle and refill glycogen stores in those two locations instead of being turned into body fat.