The problem with grains is they are carbs and carbs contribute to type 2 diabetes. One diabetic, the allowed carbs are very low. It is probably best for everyone to keep carbs at a modest level, not actually keto but maybe around 40 carbs per day. Two carb servings generally gets one up to about 34 carbs.
all I know is when I lost a whole bunch of weight and felt great I was eating cereal every morning, and sometimes I’ have it for lunch...usually wheaties or cheerios with skim milk....now I feel guilty if I eat it because of the anti cereal no carb cabal....