Its ok to eat a mango daily. Cut down on other sweets so that the calories in-take remains balanced. Mangoes are not only rich in vitamin A, (good for eyes and skin), they are also a source of anti-oxidants because of their orange colour. Mangoes are high in fibre too. Again, fresh green mango panna is re-hydrating, while a glass of milk shake can remove fatigue quickly.
One or two mangoes a day is fine and rather beneficial. If you workout everyday there is no need to worry about the calorie intake. Still,if you are too finicky, half-an-hour of brisk walking will be enough to burn the calories you consume. However, diabetics shouldn't eat more than a slice or two as mangoes have high sugar content.