Others help you gain that 20 back in pure lean muscle. Surely, there must be a better way. There are many different strategies for gaining muscle and losing fat, and many more fitness trainers, gurus and experts pushing their beliefs on hapless paying clients. For example, when doctors prescribe medicine, they can't be certain beyond a shadow of a doubt that a drug won't cause any side effects. In short, contraindications exist because people are different.
Bodies react differently to different things.
It stands to reason that, when it comes to diet and exercise, genetic variability can play a deciding role. Arnold Schwarzenegger and Lee Haney became Olympians utilizing conventional multi-set routines. Dorian Yates, on the other hand, won his Sandows employing limited sets performed with ultra-intensity. All of the above. What may work for one athlete may not work for another.