By Dan Marquette, MS, RDN, CSCS, EP-C
Weight-class sport athletes commonly compete in weight-divisions lower than their standard body weight to try and gain a competitive advantage. This weight loss is achieved through acute (e.g., rapid dehydration, glycogen depletion) and chronic (e.g., altered body composition) weight loss strategies. One dietary strategy that can aid in the acute weight-loss process is a low-residue diet (Holte et al., 2004). A low-residue diet limits high-fiber foods, such as whole grains, fruits, vegetables, nuts, seeds, and foods that increase colonic residue, such as milk (Vanhauwaert, 2015). And, it relies heavily on refined grains to meet carbohydrate demands while also utilizing dietary protein and fat to provide the bulk of energy without the intestinal bulk.
Dietary fiber is an indigestible carbohydrate that slows the transit time of foods through the large intestine and promotes regular bowel activity. Once fibrous material enters the colon, water is drawn into the intestinal space and binds to the fiber to create stool. This process, while crucial for digestive function, increases body mass. Consuming low-residue foods will allow existing gut contents to be expelled without being replaced, ultimately decreasing body mass (Holte et al., 2004). The exact amount is dependent upon an individual’s regular fiber intake; however, one could expect to lose around 1 kg of gut content within 2-7 days (Holte et al., 2004). For this reason, weight-class athletes often adopt such dietary practices prior to competition.
Traditionally, weight-class sport athletes have relied on weight-making tactics, such as dehydration and restrictive eating patterns, during the acute weight making process (Brito et al., 2012). This allows an individual to compete in a weight division smaller than their usual body weight. Doing so increases one’s strength-to-weight and power-to-weight ratio in relation to their weight division. While this theoretically provides a competitive advantage, these commonly utilized acute weight loss tactics can significantly hinder aerobic and anaerobic performance (Fogelholm, 1994). This essentially eliminates any competitive advantage gained from competing in a smaller weight division. By choosing low-residue foods prior to a weigh-in, athletes will experience a slight decrease in body mass related to the expulsion of current gut contents. This will help an athlete get closer to their competition weight without impacting muscular performance and may decrease the amount of weight being lost through methods such as dehydration.
Although a low-residue diet is commonly adopted to aid in the acute weight-making process, it may also provide performance benefits outside of weight-class sports. In power sports, for example, athletes often seek to displace their body a maximal height or distance (e.g., high jump, long jump). The acute weight loss associated with decreased gut content would increase one’s power-to-mass ratio by decreasing body mass, which could improve jump performance outcomes. Endurance athletes may also benefit from a low-residue diet prior to competition. Generally, endurance athletes are recommended to follow a carbohydrate loading protocol of 6-12 g/kg/day leading up to competition to ensure glycogen stores are saturated. Such protocols have been repeatedly shown to improve exercise performance; however, it also facilitates the binding of water to stored glycogen, causing an increase in body mass. By choosing low-residue carbohydrate-rich foods (e.g., refined grains) during a carbohydrate loading phase, an athlete can partially mitigate this increase in body mass while still saturating glycogen stores. Although this may facilitate only a slight shift in body mass, it may influence the outcome of elite-level competition when the margin of victory is exceptionally small. Therefore, a low residue eating pattern may be warranted in endurance or power sport athletes prior to competition.
It is important to note that eating patterns avoiding high-residue foods should not be followed for a prolonged period. Many avoided foods, such as whole grains, fruits, vegetables, nuts, seeds, and milk, are staples in a well-rounded diet. Avoiding these foods long-term can increase the risk of developing nutritional deficiencies and gastrointestinal complications (e.g., constipation). Because of this, a low-residue diet requires careful planning to ensure nutritional needs are met. Working with a sports dietitian to tailor such a diet approach leading up to competition can assure needs are met, and that the athlete understands how and when to transition their intake.
This article was written by a Collegiate and Professional Sports Dietitian Association Registered Dietitian (RD). To learn more about sports nutrition and CPSDA, go to www.sportsrd.org
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