Dietary Factors Related to Fitness in Young Men and Women

Background. In a previous paper we reported an inverse relationship between fitness and serum lipids in this group of young subjects. The present study investigates whether a higher fitness level was associated with a more prudent diet and whether this contributed to the observed relationship between fitness and serum lipids. Methods. The study sample, comprising 70 women and 49 men ages 23-27 years, was a subgroup of a large random sample. Aerobic fitness was measured directly as maximal oxygen uptake (ml O2 min−1 kg−1) and dietary intake as 7-day food records. Results. The highest fitness tertile had an intake of dietary fiber higher than that of the lowest tertile (25.2 g/10 MJ vs 21.9 g/10 MJ, P < 0.05) and a lower intake of sucrose (7.2 E% vs 9.8 E%, P < 0.01), whereas total fat intake and the ratio between polyunsaturated and saturated fatty acids were similar (35.4 E% vs 36.5 E%, P > 0.05, 0.39 vs 0.34, P > 0.05, respectively). No differences were observed in intake of alcohol, protein, and total carbohydrate. Multiple regression analyses showed no impact of dietary variables upon the relationship between serum lipids and fitness. Conclusions. Better fitness was associated with a better dietary composition with respect to dietary fiber and sucrose, but not to fat. The observed inverse relationship between fitness and serum lipids was not related to diet.