A commonly referenced "fact" is that a caloric surplus of 3500 kcal is equivalent to a 1 lb gain in bodyweight. But I'm confused. If you get 3500 kcal worth of, say, fatty acids, which are 9 kcal per gram, then that's about 390 g, which is just under 0.86 lb. How can you gain 1 lb of bodyweight from eating a surplus of less than 1 lb? Am I missing something?