Differential susceptibility to obesity between male, female and ovariectomized female mice.

BACKGROUND: The prevalence of obesity has increased dramatically. A direct comparison in the predisposition to obesity between males, premenopausal females, and postmenopausal females with various caloric intakes has not been made. To determine the effects of sex and ovarian hormones on the susceptibility to obesity, we conducted laboratory studies with mice. To eliminate confounders that can alter body weight gain, such as age and food consumption; we used mice with the same age and controlled the amount of calories they consumed. METHODS: We determined sex-specific susceptibility to obesity between male, non-ovariectomized female, and ovariectomized female mice. To compare susceptibility to gaining body weight between males and females, animals from each sex were exposed to either a 30% calorie-restricted, low-fat (5% fat), or high-fat (35% fat) diet regimen. To establish the role of ovarian hormones in weight gain, the ovaries were surgically removed from additional female mice, and then were exposed to the diets described above. Percent body fat and percent lean mass in the mice were determined by dual energy x-ray absorptiometry (DEXA). RESULTS: In all three diet categories, male mice had a greater propensity of gaining body weight than female mice. However, ovariectomy eliminated the protection of female mice to gaining weight; in fact, ovariectomized female mice mimicked male mice in their susceptibility to weight gain. In summary, results show that male mice are more likely to become obese than female mice and that the protection against obesity in female mice is eliminated by ovariectomy. CONCLUSION: Understanding metabolic differences between males and females may allow the discovery of better preventive and treatment strategies for diseases associated with body weight such as cancer and cardiovascular disease.

Ethanol consumption does not promote weight gain in female mice.

BACKGROUND: The prevalence of obese adult women has increased dramatically in the United States. Individuals consuming alcoholic beverages may obtain as much as 6-10% of their calories from ethanol; consequently, ethanol may contribute to a positive energy balance and weight gain in women consuming ethanol. The objective of these studies is to determine if ethanol consumption affects weight gain or body fat levels in female mice. METHODS: In order to determine the effects of ethanol consumption on weight gain, female mice were given either water or 20% w/v ethanol in the drinking water; mice were then placed on 1 of 3 diets for 20 weeks: (1) 30% calorie-restricted diet, (2) low-fat diet or (3) high-fat diet. Mice were scanned using a GE Lunar Piximus Densitometer to determine body fat, lean body mass and bone mineral density. RESULTS: Mice consuming the high-fat diet had the highest body weight. Moreover, ovariectomy exacerbated the effects of the high-fat diet. That is, ovariectomized female mice consuming the high-fat diet gained a higher amount of body weight and adipose tissue than non-ovariectomized mice consuming the high-fat diet. Ethanol-consuming mice did not have a higher susceptibility to gaining body weight or body fat, even though they tended to have higher caloric intake than water-consuming mice. CONCLUSIONS: In female mice that consumed a high-fat diet, chronic ethanol consumption did not increase susceptibility to gaining weight or becoming obese.