IF you read carefully Supplements itself says that it is only “SUPPLEMENT” not FOOD. It is not the replacement of food, it only helps us to complete our diet, which you can’t able to cover through your food.
There are generally 3 forms of supplements, TO GAIN WEIGHT, TO LOOSE WEIGHT, and which keep maintaining your BODY WEIGHT & MUSCLES.
Only one supplement can’t cover it all. To perform an exercise on regular basis your body needs stamina, for which you need protein & carbs. You can perform well while doing exercise you need PRE-workouts. After finishing your exercise your body required repairing of tissues for which you need post workouts/Glutamines. And most of the above you need GOOD FOOD. HOPE & DEDICATION