the problem with dried food, any food-freezedried,flake or pellets, is that as keepers we generally just put them in the water, the fish are hungry and they eat it dry. then they expand in the GI tract as they absorb water. we overfeed, as the fish seem hungry, and all that dried food expands in their digestive tract, subsequently blocking them up. which is why its good practice to feed bettas peas, to keep things moving (most use dry pellets as staple with various "treats" during the week). if you feed any sort of frozen or live food you run into less complications in the long run. it really isnt a matter of too much fat or protein, simply that it is dry and expands as it absorbs water. it is good practice if you feed any sort of dry food(freezedried, pellets and flake, in order of importance) to soak the food in a cup of tankwater for at least 10 minutes before feeding to certain fish where it may pose a problem (bettas being one due ot their short digestive tract). honestly, its better to use frozen foods (bloodworms and daphnia with bbs as a treat) as staple and feed them dry food and fiber(peas) as treats.
hope that helped.
cheers