I am in great favor of mushrooms.
Mushroom is a natural high nutritional food. It contains high protein and no fat, hence its good from fitness point of view. It is said to be the perfect meat alternative. Some types of mushrooms are used in medicines and some are used for genera eating. Oyster mushroom is the most common eatable mushroom.
I will prefer to use vegetables. Vegetables are naturally good for our health and fitness. They keep cholesterol and fat level in control. Vegetables provide energy with less calories hence good for fitness. Caffeine in some cases may harm our muscles and cause some liver problem.
Weight gain is possible in two ways, more fat, or heavy massive muscles. The first one is not healthy and the second one is healthy choice for most of the people. So such foods that contain high protein and low fat would be best to bulk up muscles and keep you in good shape because of low fat. Strong muscles will ultimately increase body weight.
Fish contains high protein that is good to provide us enough energy. The most important thing about fish that they contain omega 3 fatty acids that can't be get properly through other foods. Fish is good to provide energy while keeps weight in control.