This is correct. Further, I don't know what it has to do with race - all humans respond to low calorie diets in the same way. There is the case of lactic intol

This is correct. Further, I don't know what it has to do with race - all humans respond to low calorie diets in the same way. There is the case of lactic intolerance due to loss of a particular gene. I'm not aware of any similar gene being involved in insulin intolerance.