| Popis: |
Our research has shown that 800 kcal/day sucrose diets, unlike pure protein diets, maintained resting metabolic rate (RMR) and triiodothyronine (T3) levels. Concern that thermogenesis from sucrose might reflect protein catabolism led to this study, in which 23 obese women were studied as inpatients for 2 weeks on diets (kcal = 50 percent of RMR) containing either 93 percent sucrose (S, n = 7), sucrose plus protein (75 percent/20 percent, SP, n = 9), or fat plus protein (75 percent/20 percent, FP, n = 7). RMR, leucine kinetics (1-14C)leucine method) and nitrogen balance were measured. RMR fell (P less than 0.03) with SP and FP (-8.4 +/- 2.5 percent, -7.5 +/- 2.5 percent), but was maintained by S (+ 0.3 +/- 2.4 percent, P = 0.05 vs. SP and FP). Plasma leucine decreased (P less than 0.01) with S and SP by 36.6 +/- 4.0 percent and 17.0 +/- 4.7 percent, but increased by +52.8 +/- 9.0 percent (P less than 0.01) with FP (P = 0.0001 vs. S or SP). Leucine turnover, oxidation, and nonoxidative disposal all decreased (P = 0.0001) with S and with SP, in contrast to FP, in which these parameters were unchanged (all P = 0.0001 vs. S or SP). Cumulative (2 week) nitrogen loss was least (P = 0.001) in SP (-2.56 +/- 0.41 mol) compared with S (-4.37 +/- 0.19 mol) and FP (-4.76 +/- 0.12 mol), which did not differ. Since inclusion of sucrose in hypocaloric diets maintained RMR while decreasing leucine turnover, oxidation, and nitrogen loss, we conclude that the thermogenic effects of sucrose do not depend on protein catabolism. |
