100% Gold Standard Whey from Optimum Nutrition is a terrific product both economically and performance wise. This is a great tasting whey protein with 24g of pure protein and only 1g fat and 3g carbs per serve, it is also full of excellent quality BCAA's, these factors make the product ideal for somebody aiming to stay lean while putting on lean mass. I took 100% Gold Standard Whey for close to 3 months before my supply ran out :( , it mixes perfectly and is easy on the stomach, helping you to perform without feeling weighed down. I noticed no negative side effects from this product and the positives were increased energy, recovery and consistent muscle gain. The price is reasonable considering the quality and I would recommend trying this product!