Ivebeen tested and not diabetic, but i keep getting dizzy/faint if i don't snack between meals, during exercise, or in the heat. any suggestions why?

Hypoglycemia: You still might have symptoms of hypoglycemia. Maintain good hydration also, avoid food high in sugar.

Low BS reaction: You are probably having reactive Hypoglycemia , especially if your snacks between meals are sugar loaded . Your body will secrete Insulin to take care of the carbs you ate , but usually overshoot and lower your BS too much snd you wi feel dizzy snd light headed and the cycle goes on . Limit your sugar intake snd make your snacks proteins or complex carbs .