This is simply untrue. He was at a weight for his height where serious muscle gain for an athlete could follow. He was at an age where it's possible to have the largest possible muscle gain. He has access to the finest trainers and nutritionists that money can buy. As the Captain mentioned he was at 179 the last week of February. Getting to 195 by the end of July is possible through a legal but strenuous process overseen by professional nutritionists and trainers especially if he is one of the folks where muscle gain comes easily.
Also, please note that the typical human can have a 5 pound swing in weight during a day, and it could be as much as 20 pounds.