PHOSPHATE SUPPLEMENTATION PREVENTS A DECREASE OF TRIIODOTHYRONINE ANDINCREASES RESTING METABOLIC-RATE DURING LOW-ENERGY DIET

Thirty overweight women participated in 8 week slimming program consis ting of a self-controlled low-energy diet (4.2 MJ/day) supplemented wi th highly viscous fibres and mineral tablets containing calcium, potas sium and sodium phosphates (Redusan Combi, Biokraft Pharma AB, Sweden) . Half of the patients received in double blind manner mineral tablets during first 4 weeks and placebo (without phosphates) during next 4 w eeks (group 1) while the remaining patients were treated (cross-over) with placebo first and mineral tablets in the final period (group 2). The rate of weight loss was similar in groups 1 and 2 (4.7 vs 5.2 kg d uring the first 4 weeks and 2.7 vs 3.0 kg in the further 4 weeks). Dur ing periods of phosphate supplementation, the resting metabolic rate ( RMR) increased by approx. 12% (p<0.05) in group 1 and 19% (p<0.05) in group 2. Phosphate supplementation ameliorated also a decrease in plas ma triiodothyronine level and a decrease in thyroxine to triiodothyron ine ratio. There were no differences between groups in the plasma insu lin, catecholamine, growth hormone, cortisol and testosterone levels. Phosphate supplementation did not affect plasma lipids or blood glucos e concentration. It is concluded that phosphate supplementation in obe se patients on a low-energy diet enhances RMR irrespectively of the ra te of weight loss. This efect seems to be, at least partly, due to an influence of phosphates on peripheral metabolism of thyriod hormones.