Competitive bodybuilders are judged on the basis of muscular size, shape, definition, density, proportion, and visual presentation (International Federation of Bodybuilders, 1987). Bodybuilders generally train for muscular size during the off season and reduce body fat several weeks or months before competition (Elliot, Goldberg, Kuehl, & Catlin, 1987; Hickson, Johnson, Lee, & Sidor, 1990; Balon, Horowitz, & Fitzsimmons, 1992). The body fat of male competitive bodybuilders during the off season have been measured at 9.8% (Hickson, Johnson, Lee, & Sidor, 1990),13.1 ±2.8% (Kleiner, Calabrese, Fielder, Naito, & Skibinski, 1989), 9.3 ±0.75% (Katch, Katch, Moffatt, & Gittleson, 1980). The relative absence of subcutaneous fat can enhance the appearance of muscular development by revealing the size, shape, and striations of the underlying muscles. In an effort to reduce body fat and maintain lean body weight, bodybuilders typically employ restrictive dietary practices, intense training, and the self-administration of pharmaceuticals.
Off Season Diet
Kliener (1989) found competitive bodybuilders consumed an average of 5739 ±2500 kcalories (2451-19760 kcal) when not preparing for competition. One subject consumed only 2451 kcalories, where as another subject reported consuming 19760 kcalories; 1290 gm of protein, 2443 gm of carbohydrate, and 663 gm of fat. Some subjects reported eating every two hours and many claimed to awaken to eat during the night. This extreme kcalorie consumption is rare in the literature since Kliener (1990) gave inaccurate reference to bodybuilders who reported consuming 17,333 (+/- 4554) kcalories daily (Kleiner, Bazzarre, & Litchford, 1990). In the actual study, they documented the daily consumption of 17,333 kilojoules (4127 kcal), not 17,333 kilocalories as reported (Faber, Benade´, & van Eck, 1986). The most extreme protein intake reported in the research in 1989 was 3.5 g/kg/day. This amounted to 20% of the subject's daily caloric intake (Paul, 1989; Dragan, Vasiliu, & Georgescu, 1987).
Bodybuilders have been known to rapidly gain weight prior to competition after breaking their precontest diet (Hildebrand, Saldanha, & Endres, 1989; Hickson, Johnson, Lee, & Sidor, 1990). Overfeeding has been shown to lead to an increase of lean body mass possibly as a result of increased plasma somatomedin-C, testosterone, and insulin (Forbes, Brown, Welle, & Underwood, 1989). Insulin facilitates and increases the transport of glucose and amino acid in muscle cells. Insulin can also stimulate the synthesis and storage of cellular protein and glycogen in muscle cells (Di Pasquale, 1993). Although insulin's effect on amino acid uptake into the cell may not be indicative of increased muscle mass (Florini, 1987), insulin may permit maximum protein synthesis to occur in ideal physiological situations (Di Pasquale, 1993). Insulin and other anabolic compounds may act synergistically to produce significant anticatabolic and anabolic effects (Di Pasquale, 1993). Intercellular amino acid is essential to the action of anabolic steroid's role in protein synthesis.
It must be noted, though, insulin increases lipoprotein lipase action and can enhance the synthesis and storage of triglycerides in fat cells (Di Pasquale, 1993). Anabolic steroids may play a physiological role in the regulation of fatty acid oxidation in liver and fast twitch muscle mitochondria even in the absence of intense physical training (Guzman, Saborido, Castro, Molano, & Megias, 1991). It has been argued that a high fat diet has a positive effect on muscle growth (Di Pasquale, 1992).
Muscle glycogen synthesis is greatest within 2 hours proceeding exercise. Exercise increases the muscle's sensitivity to insulin, predominately, during the 4 to 6 hours after exercise. During this time, muscle glycogen synthesis has been shown to be greater with ingestion of simple as compared with complex carbohydrates. After which, muscle glycogen can be resynthesized near pre-exercise levels within 24 hours, equivalently with either carbohydrate form (Friedman, Neufer, & Dohm, 1991). After 24 hours, muscle glycogen can increase very gradually, succeeding normal levels over the next few days (Ivy, 1991).
Many bodybuilding athletes believe nutritional supplements are necessary for optimal progress, although many claims made for commercially marketed supplements for bodybuilding athletes are not supported by current research (Grunewald & Baily, 1993).