Ahmed Ismaeel (Ahmed_Ismaeel@baylor.edu)

Nutrition Sciences, Baylor University, Waco, TX, 76706, USA

Background

A recent literature review [1] identified that many previous older studies have reported deficiencies in intakes of several micronutrients in bodybuilders Notably, a new “flexible” dieting strategy, popularly known as “if it fits your macros” or “IIFYM,” has recently become widespread. In contrast to restriction-based dieting, IIFYM instead focuses on monitoring individual macronutrient intake, with less regard for the specific foods consumed. The purpose of this study was to assess selected micronutrient intakes of male competitive bodybuilders and to compare the intakes of those who follow flexible dieting and strict dieting regimens.

Methods

Subjects for this study were male competitive bodybuilders, recruited online via social media outlets. The Diet History Questionnaire, Version 2.0 (DHQ-II) [2], a semi-quantitative food frequency questionnaire (FFQ), was used for this study to assess micronutrient intakes. A pooled t-test was used to test whether flexible dieters and strict dieters consume, on average, the same mean amount of each micronutrient, with α being significant at p < 0.05.

Results

Thirty individuals were included in the final analyses, of which 14 followed flexible dieting and 16 followed strict dieting. Ages ranged from 20 to 50 years old, with a mean age of 29.1 years (SD = 6.9). Subjects consumed an average of 2577.2 (SD = 955.1) kilocalories, with an average fat intake of 83.6 g (SD = 41.3), an average carbohydrate intake of 324.4 g (SD = 105.2), and an average protein intake of 163.4 (SD = 70.4). Of the vitamins and minerals assessed in this study, vitamin A, vitamin D, vitamin E, and potassium were consumed at levels below the RDA. In addition, dietary fiber intake was below current recommendations. Nutrient data for all subjects are summarized in Table 1.

There were no significant differences between male flexible and strict dieting bodybuilders when mean nutrient intakes were compared. However, in the strict dieting group, average intakes were higher for all nutrients, and a greater proportion of individuals met the RDA/AI. Table 2 highlights the differences in nutrient consumption between the two groups.

Conclusions

Based on the results of this study, male competitive bodybuilders may need to pay more attention to their intakes of certain micronutrients. Vitamins A, D, and E, and dietary fiber were all consumed below recommended amounts. Vitamins A and E are both important antioxidants, vitamin D has been associated with muscle strength [3], and dietary fiber can increase satiety, regulate blood glucose, and is inversely associated with body fat [4]. While there were no large differences between the nutrient intakes of males who follow flexible dieting compared to strict dieting, the greater proportion of individuals in the flexible dieting group who were not meeting the RDA for several nutrients suggests that this group should especially take their micronutrition into greater consideration.

References

1. Helms ER, Aragon AA, Fitschen P: Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014, 11:20.

2. Diet History Questionnaire, Version 2.0. National Insitutes of Health, Epidemiology and Genomics Research Program, National Cancer Institute. 2010.

3. Chiang CM, Ismaeel A, Griffis RB, Weems S: Effects of vitamin D supplementation on muscle strength in athletes a systematic review. J Strength Cond Res. 2017, 31(2): 566-574.

4. Slavin JL: Dietary fiber and body weight. Nutrition. 2005, 21(3): 411-418.

Table 1 (abstract P2). Dietary intake in male competitive bodybuilders Full size table