The concept of bulking, or eating at a major caloric excess, became popular with the introduction of insulin hGH and IGF-1, in the 1980s, to shuttle a massive of additional nutrients to an already anabolic steroid enhanced body. 16-20 week "cutting" diets became popular at the same time as a direct result of huge, excessive calorie diets. Eating at a caloric deficit for 16-20 weeks will demolish a huge amount of lean muscle mass unless one is on large doses of insulin, anabolic steroids, growth hormone and growth factor to maintain lean mass and DNP, clenbuterol and ephedrine HCL to burn fat. Natural bodybuilders do not have the assistance of anabolic drugs to shuttle superhuman levels of nutrients into their body without excess lipid storage. The concept of "bulking" has, thus, no role in a natural bodybuilder's diet, because adding excess calories to their diet will not induce extra muscle gains - it will only induce extra fat storage. Since, bulking is out of the question for natural bodybuilders, the idea of "cutting" (eating a major caloric deficit to burn fat) does not make sense. A natural bodybuilder can always stay at a low bodyfat by eating a disciplined high protein diet without overdoing the calories or macronutrients. There is a role for a contest prep diet for the natural competitor, but it should not last longer than 10-12 weeks MAXIMUM. If a natural needs to diet for 16-20+ weeks to get in shape for a contest, they have gained too much fat in their offseason and are just wasting time. One can naturally gain muscle mass and comfortably walk around 10 weeks out from contest condition at all times.