20 kg increase in lean mass

following 3 weeks of an increased consumption of fish oil. In their study, they added fish oil to the diet, but kept total fat and energy constant between the treatments. In the present study, the fish oil was added on top of an ad libitum diet, with instructions given to the subjects to maintain their normal dietary patterns throughout the study. Similarly, Selleck Tucidinostat Hill et al [22] found a significant reduction in fat mass following 12 weeks of supplementation with fish oil in overweight subjects. They also observed an increase in lean mass in the fish oil group, however, like the data reported by Couet et al. [21], it did not reach significance. Thorsdottir et al. [23] recently Selonsertib found that supplementation with fish oil, or inclusion of fish in an energy-restricted diet resulted in significantly greater weight loss in young men. Additionally, they found that young men taking the fish oil supplements had a significantly greater reduction in waist circumference compared to the control group, or the group that increased their dietary intake of fish. Unlike the Couet et al. study [21], we did not observe an increase in RMR, or a decrease in RER following fish oil treatment. The failure to find an increase in RMR

following fish oil treatment is hard to explain given the significant increase in lean mass observed in the present study. Several studies have shown that lean mass is the largest determinant of RMR [28–30], and decreasing lean mass decreases RMR [31], while increasing lean mass increases RMR [32]. Therefore, it would be expected that the increase in lean mass would correspond to an increased RMR following fish oil treatment. In the Couet et al. study [21], metabolic data were measured for 45 min following a 90 min rest period. This is a longer time period than the 40 min used in the present study. However, it is doubtful Mephenoxalone that this methodological difference between the studies contributed to the differing effects observed for RMR and RER values since recent studies have shown that very short rest periods (as little as

5 min) produce reproducible results that correlate extremely well with RMR measures made over much longer time periods [33, 34]. It is also unlikely that the use of a subset (n = 24) of the total subject population can explain the failure to observe any metabolic changes since analysis of the 24 subjects found that they responded similar to the entire group in regards to body composition changes. It remains unclear why the increased lean mass observed following fish oil treatment did not correspond to an increase in RMR. Selleck PHA-848125 Intuitively it would make sense that if fat mass was reduced, but resting metabolic rate did not change following fish oil treatment, then the amount of calories coming from the oxidation of fatty acids should be increased. However, this was not the case in the present study.