INCREASED POSTPRANDIAL ENERGY-EXPENDITURE IN OBESE WOMEN AFTER PERORAL K-PHOSPHATE AND MG-PHOSPHATE

Energy expenditure (EE) was studied in 15 obese (BMI > 27.5, median 29 .2) and 15 lean (BMI < 22.9, median 21.7) healthy, postmenopausal wome n before and after peroral orange juice with or without K- and Mg-phos phate supplementation. The women, 56-58 years old, were studied in a d ouble-blind, crossover experiment on two separate days. They received 100 ml of orange juice (10 g of carbohydrates) with or without a suppl ement of Kf (35 mmol), Mg2+ (17 mmol) and HPO42- (39 mmol). Measuremen ts were made before and 30 and 60 min after the stimuli. Intake of jui ce only had no effect on EE in either the lean or the obese subjects. When the minerals were added, EE (+6.3%; p < 0.001) increased signific antly in the obese group with in a maximum 30 min after stimulus, whil e no such increase was seen in the lean group. The difference between the groups was significant (p < 0.05) and so was the difference in the obese group with or without minerals (p < 0.01). We conclude that an addition of potassium/magnesium-phosphate to glucose increases the pos tprandial thermogenesis in obese postmenopausal women, but not in lean ones.