Can you use a weight gainer and a muscle builder at the same time?
I have a 16 year old football player who is trying to build up his muscle and strength. He is 5’11 and 160#. He has been using "Muscle Milk" with some success but he has between 0 and 5% body fat, leaning more toward the 0 side. We know he needs to use a weight gainer but want to know if he can use that along with his muscle milk.

all those products are a big scam to make you pay a lot of money.
he needs to eat lots of protein (meat, chicken, deep sea fish) and also carbs (pasta, whole rice, legumes)
and forget about all those artificial poisons.
tell him to use AST VP2 protein powder and add AST GL3 Glutamine to it, 5g after workout.
Eat more fish and red meats.
Weight gainer: waste of money, easliy make your own with:
protein powder,carb powder and oil:
VP2 protein+30g of waxymaize starch (carb slam)+flax oil+5g glutamine powder
take it after workout
VP2 by itself in the morning when wake up, b4 training, after(see above) and b4 bed