Is there a difference in body composition before and after eating in men and women, and how strong does the skeletal muscle mass correlate with leg strength?

Background: Health risks associated with, for instance, body fat is increasing worldwide, and to identify them, an assessment of body composition is necessary. The knowledge of the body composition play an important role in preventing and treating metabolic syndromes associated with multiple diseases, such as diabetes (type-II), obesity and cardiovascular diseases. Nowadays, measuring of body composition occurs during fasting conditions with no eating or drinking four hours prior the measuring, which means a limited amount of people can be measured each day. Usually skeletal muscle mass is measured concurrent with bodycomposition, however it could be helpful if there was an easier and quicker method, such as measuring leg strength. It could increase the clinical use and utility if measuring of body composition does not need to be in a fasting condition, and even more if leg strength could estimate skeletal muscle mass. Aim: The main aim for the present study was to measure body composition in men and women with a bioelectrical impedance analyzer, before and after eating, to identify any changes. The second aim was to discover how strong the skeletal muscle mass correlate with leg strength through a vertical jump test. Methods: In the present study 27 subjects (10 men and 17 women) participated, with a mean age of 37.9 ± 12.2 years. A bioelectrical impedance scale (InBody 770) was used to measure body composition before (fasting condition) and after eating (60, 90 and 120 minutes). Each subject also executed three countermovement jump before they were allowed to eat, where the highest jump was registered.Results: The present study showed significant differences (p≤0.05) in body composition for multiple variables 60 minutes after food intake and no significant differences in body composition after 90 and 120 minutes, except for the minerals that showed a significant difference throughout all the testing. The correlation between skeletal muscle mass and leg strength was weak for both gender, with a correlation coefficient 0.08 (men) and -0.03 (women).Conclusion: The present study showed no significant differences in body composition before food intake compared to 90 and 120 minutes after. These results indicate that the guidelines of 4 hours fasting, may not be necessary. Whether the subjects need to be in a fasting condition or not when measuring body composition, still needs more investigation. The result for the measurement of skeletal muscle mass suggest that the preferable method still is measuring body composition rather than measures of leg strength