How fat is obese?

The aim of the study was a comparison between body fat measurements and body mass index. We analyzed the data of 890 subjects, 596 females and 294 males, ranging in age from 18 to 83 years, in body mass index (BMI) from 14 to 54 kg/m(2), and in body fat percentage (BF%) from 4% to 57%. A considerable number of subjects, both males and females, could not be classified as obese based on their BMI alone. Such a misclassification is undesirable, especially in general practice, and it calls for diagnostic criteria other than the BMI alone to be used for obesity.

Effect of acute and chronic branched-chain amino acids on energy metabolism and muscle performance.

The aim of this study was to report the effects of acute and chronic branched-chain amino acids (BCAA) administration on energy metabolism and muscle performance. In the acute study which was double-blind, cross-over and placebo-controlled, 12 healthy male volunteers were administered orally on two consecutive days either BCAA (14.4 g/day) or isocaloric placebo; this was followed by measurement of oxygen consumption (VO2) and carbon dioxide production (VCO2) for 180 min by indirect calorimetry. In the chronic study, 10 healthy male volunteers were supplemented with BCAA (14.4 g/day) for 30 days. Before (T0) and after (T1) chronic BCAA administration, VO2, arm muscle area (AMA) and maximal voluntary contraction of forearm muscles (grip strength, GS) were evaluated. Acute study: Both meals increased mean respiratory quotient (RQ) from baseline: in the placebo group, this increase was short-term only (between 15 and 60 min), while this effect on RQ lasted for 120 min in the BCAA group. Moreover, between 30 and 90 min, mean RQ was significantly higher in the BCAA group than in the placebo group. Chronic study: GS increased significantly following chronic BCAA administration without significant changes in the AMA. At T0, VO2 increased significantly during the GS test, whereas at T1 no significant increase was observed. In conclusion, no excess thermogenesis could be detected as compared with placebo following acute BCAA administration, indirectly suggesting a relevant contribution of peripheral catabolic (bypassing liver) pathway to BCAA metabolism; furthermore, chronic BCAA supplementation improved the physical fitness of untrained healthy subjects, as demonstrated by the lack of 02 uptake increase during sustained hand grip test.