The Specific Impact of Nutrition and Physical Activity on Adolescents' Body Composition and Energy Balance.

Purpose: The aim of the present study was to identify the contribution of nutrition, physical activity (PA), and total energy intake and expenditure on body weight and composition in adolescents. Methods: Body composition, PA, and dietary intakes from 904 Greek adolescents (446 boys and 458 girls; Age: 14.6 ± 1.5 yrs), were evaluated. All participants were assigned into three groups according to their age-sex adjusted Fat Mass Index: (A) Normal weight (N; N = 503), (B) Overweight (OW; N = 253), and (C) Obese (O; N = 148). Results: Significant differences were found for body weight and composition, basal metabolic rate (BMR) expressed per kg of body mass (normal weight children exhibited the highest values), physical-total energy expenditure, and energy balances between the groups (η2: 0.138 to 0.657; p < .05). In contrast, no differences were found for macronutrients' and total energy intakes, food consumption and quality (η2: 0.002 to 0.099; p > .05) between the three examined groups. Strong, negative correlations were observed between body weight, body fat percentage, PA, and total energy expenditure (r: -0.311 to -0.810; p < .001). Lower, negative correlations were found between body weight, body fat percentage, and macronutrients' daily intakes (r:-0.235 to -0.432; p < .05). BMR and total energy expenditure had strong, negative relative strengths for the determination of body weight and fat percentage. Conclusions: In conclusion, it seems that BMR, PA, and total daily energy expenditure expressed per body weight and not the nutritional and total energy intakes, were the primary determinant parameters of body composition and weight in adolescents.

Nutritional Routine of Tae Kwon Do Athletes Prior to Competition: What Is the Impact of Weight Control Practices?

OBJECTIVE: The purpose of the present study was to investigate and assess the common dietary and weight management strategies of Tae Kwon Do (TKD) athletes prior to national competitions, as well as to examine the relationships between these strategies and body weight reduction and sensation of physical condition. METHODS: Sixty (n = 60) TKD athletes, 23 women (19.4 ± 2.9 years) and 37 men (20.4 ± 3.6 years), with at least 12.1 ± 3.1 years of experience, participated in the present study. The athletes recorded their dietary intake and physical activity for 3 training days and on a competition day. Bioelectrical impedance was used for body composition estimation. RESULTS: Male athletes consumed 1918 ± 685 kcal/24 hours and 1974 ± 669 kcal/24 hours on training and competition days, respectively, and women 1814 ± 446 kcal/24 hours and 1700 ± 439 kcal/24 hours. TKD athletes had significant negative energy balance (48.6% ± 17.8% to 60.3% ± 26.9%; p < 0.05), with the majority of macro- and micronutritional elements being lower than the recommended values, with significant differences between them, as well as within groups, between weekdays and weekend days (p < 0.05). Females lost most of their weight 2 weeks before the games (3.50 ± 1.00 kg), and males lost most of their weight 3 weeks before (3.16 ± 2.48 kg). The majority of TKD athletes were guided by their coaches for weight management strategies. No significant correlations were found between any body composition variable, weight loss, and any nutritional intake at any time point (p > 0.05). CONCLUSIONS: These data suggest that the methods of TKD athletes for rapid weight loss are guided by unspecialized professionals, leading to significant malnutrition, because certain deficiencies in both macro- and micronutrient content are present, with no guaranteed specific reduction of their body mass.