Meh, weight gainers are overpriced and underpowered. Weight gainers usually just put on fat on you because they're just whey concentrate with dextrose or maltodextrin. If you overwhelm your body with too much protein and sugar at one time, you'll overwhelm the metabolic processes that get those nutrients into muscle so your body will just take those calories and store them in fat cells. That's why slower proteins and carbs (think chicken with whole wheat pasta or lean beef with brown rice or cottage cheese before bed) are a staple in any bodybuilding diet.
If you insist on using a weight gainer, I suggest you do something like this:
- TrueProtein powder blend, something like 25% milk protein isolate, 25% egg white protein, 25% whole egg protein, 25% beef protein isolate
- Milk, preferably raw whole milk
- Frozen raspberries
- 1 banana
- Oats
- Cottage cheese
Mix it all together in a powerful blender and you just made yourself a very solid weight gainer shake. The oats are a great source of complex carbs and the dietary fiber from the oats and raspberries will hopefully slow digestion enough that you'll get a very steady release of the carbs found in the milk, raspberries, and banana. The cottage cheese, milk, and milk protein isolate are all great sources for casein protein, which will provide your body with continuous amino acids for at least 8 hours, probably longer. You'll get some whey from the milk and milk protein isolate. The egg protein and beef protein will provide you with a steady amino acid release for at least a few hours. This kind of homemade weight gainer shake will not overwhelm your body's metabolic pathways like the low quality stuff you buy at GNC.
In addition to a weight gainer shake, you should probably take a shot of cod liver oil before going to bed for the Omega 3s and the Vitamin D.