Optimum Nutrition's Serious Mass may be the weight-gainer to end all weight-gainers. With an unbelievable 1250 calories per serving, one shake's worth of Serious Mass could feed a small village. OK, not really, but Optimum Nutrition wasn't kidding around when they named this weight gain powder Serious Mass. It's not a product for everyone. But by the same token, intensively-training younger athletes, or those already in peak condition don't have average metabolisms or nutritional needs. For these athletes, getting enough calories tomaintain their muscle mass and strength is hard enough, let alone consuming enough to grow quality mass. Ordinary protein powders and meal replacements don't cut it for these users. A weight-gainer would be a better choice, but most of them are just glorified protein powders, with added carbs and an arbitrarily increased serving size. So, don't mess around with generic weight gainers. If you really need calorie-dense supplement to help put on some size, Serious Mass is much better choice for you. Serious Mass is the most calorie-intense shake on the market, packing an unbelievable 50 grams of a mass-building protein blend - more than 8 whole eggs - into each 1250 calorie shake. Besides protein, Serious Mass is also fortified with creatine, glutamine, glutamine peptides, vitamins and minerals, everything you need to build lean mass, provided you're training hard. Granted, not everyone needs that kind of nutritional density, so keep in mind that you can use smaller servings of Serious Mass, if that suits your needs better. You can expect great taste and mixability from Serious Mass, since it's made by protein powder mega-giant Optimum Nutrition. Nobody offers more flavors, or better flavors, in their protein line than Optimum Nutrition. So while you don't use a product like Serious Mass for its taste, it's nice to not have to force a shake down on account of lousy or lackluster flavor. Mix with water, or with milk for even more calories and protein.