Location: Children's Nutrition Research CenterTitle: Galactose promotes fat mobilization in obese lactating and nonlactating women) Author
Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2010
Publication Date: 2/3/2011
Citation: Mohammad, M.A., Sunehag, A.L., Rodriguez, L.A., Haymond, M.W. 2011. Galactose promotes fat mobilization in obese lactating and nonlactating women. American Journal of Clinical Nutrition. 93(2):374-381. Interpretive Summary: This study was carried out to determine whether the type of sugar in the diet, would affect the breakdown and burning of body fat in obese women. Specifically, we investigated whether a drink containing galactose vs. glucose (as the only sugar source and the same caloric and protein contents) would increase the breakdown and burning of fat in obese breastfeeding, and obese non-breastfeeding women and without affecting milk production in obese breastfeeding women. We demonstrated that during galactose feeding in both obese breastfeeding and non-breastfeeding women, blood sugar, and insulin concentrations were lower and the breakdown of fat was higher than during glucose feeding. During galactose feeding in all women combined, more fat and less protein were burned when compared to glucose feeding. Breast milk production was similar between glucose and galactose feeding. In this short-term study, we concluded that galactose consumption may facilitate body fat loss when compared to glucose. However, long-term studies will be needed to determine whether a weight loss diet involving galactose as the only sugar, would increase the loss of body fat (and therefore weight) in obese people.
Technical Abstract: Galactose consumption as the only carbohydrate source, results in little increase in plasma glucose and insulin concentrations when compared with fasting. Lower insulin might promote endogenous lipolysis during meal absorption, which may facilitate fat loss. The objective was to test the hypothesis that consumption of an isocaloric, isonitrogenous galactose drink, would result in higher rates of lipolysis and fat oxidation than consumption of a glucose drink in obese lactating and nonlactating women. Seven healthy, obese, exclusively breastfeeding women and 7 healthy, obese, nonlactating women were studied on 2 occasions according to a randomized, crossover, single-blinded design. Subjects received drinks providing 70% of the daily estimated energy requirement, of which 60% was either glucose or galactose. The primary outcomes were the rate of appearance (Ra) of glycerol and palmitate, and the secondary outcomes were glucose Ra, milk production, energy expenditure, and substrate oxidation. Plasma glucose and insulin concentrations were lower (P < 0.05) and those of glycerol, palmitate, free fatty acids, and triglycerides were higher (P < 0.05) during galactose than during glucose feeding in both nonlactating and lactating women. During galactose feeding, glucose Ra was lower (P < 0.01) and glycerol, palmitate, and free fatty acid Ra were higher (P < 0.01) in both groups. During galactose feeding in all women combined, fat oxidation was higher (P = 0.01) and protein oxidation was lower (P < 0.01). Milk production, energy expenditure, and carbohydrate oxidation were similar between glucose and galactose feeding. Galactose consumption is associated with higher endogenous fat mobilization and oxidation during meal absorption. Long-term studies are required to determine whether galactose as an exclusive carbohydrate source would promote body fat loss in obese subjects.