Not only. First, some people, eating the same excess calories than you, won't store it as fast. Genetics play a role. Also, you may store more fat or not depend

Not only. First, some people, eating the same excess calories than you, won't store it as fast. Genetics play a role. Also, you may store more fat or not depending of: - the time of the day you eat it (you will more likely store things if you eat it late than early in the morning due to your homonal cycle) - the duration on which you eat it (the infamous 9 hours popularized by dr rhonda patrick) - what you mix. Eating the same amount of calories in pure fat, or in a mix of 50% fat and sugar will not result in the same process by the liver. - insulin sensibility. Which is influence by the quality of your food. E.G: how much sugar it contains. - ability to process said food, again influenced by the state of irritation of your intestine and your microbiome, and hence influenced by the quality of your food. E.G: adult can get irritated intestines by intaking dairy product after they lost their childhood ability to proess it as well. I know it's a convenient shortcut to say "calories in, calories out", especially since it's easy to demonstrate (the anecdotal Twinkie diet made us all think). But if we keep repeating that, we are not helping people to lose weight. Dieting has a very low success rate because of the solely focus on the calorie count, while using the informations above as well lead to less rebound and frustration in my experience.