New research published in the Journal of Physiology has shown that female athletes who do not have enough energy intake to cover the energy costs of their exercise and physiological functions experience a negative impact on both their health and training response.
The study included 30 healthy females. During the study, participants completed individual training programs focused on increasing muscle mass, strength, and general fitness. Additionally, the participants were divided into two groups: each group started with five days of optimal energy intake, then the first group transitioned to a low energy availability (LEA) diet in which their energy intake did not match their energy expenditure, while the second group continued optimal energy intake. Daily muscle protein synthesis was measured for each participant along with changes in body composition, resting metabolic rate, blood biomarkers, and 24-hour nitrogen balance.
The results showed that the LEA diet reduced daily integrated muscle protein synthesis compared to the optimal energy intake diet. In other words, athletes on the LEA diet built less muscle despite being on the same training program. Additionally, women on the LEA diet experienced reductions in lean muscle mass, urinary nitrogen balance, thyroid hormone concentrations, and resting metabolic rate.
The authors of the study noted that our culture often encourages women to constantly try to lose weight, and athletes can face particularly extreme pressures. However, the results of this study show that focusing on weight loss can have negative effects on both health and training, including hormone disruptions and decreases in muscle building. To counteract this, active women and female athletes should be very conscious of their energy intake during training and to be sure to match their energy intake with their expenditure.
Sources: Journal of Physiology, Science Daily
