• Approximately 61 percent of the United States population is overweight or obese, with women having higher rates of obesity than men.¹

• For adults, a body mass index of 25 or more is considered "overweight" and a BMI of 30 or more is considered "obese".

Women’s Risk for Obesity

• Pregnancy and menopause are significant factors in the development of obesity in women, suggesting that fluctuations in reproductive hormone concentrations uniquely predispose women to excess weight gain.²

• Obesity risk is greater among men and women with fewer years of education and poorer economic circumstances and among women, but not men, of lower occupational status.³

• Women generally have a higher percentage of body fat than men, and there are indications that basal fat oxidation is lower in females as compared to men, thereby contributing to a higher fat storage in women.⁴

• Serotonin contributes to the regulation of food intake and appetite behavior. As body mass index (BMI) increases, the amount of serotonin synthesis decreases, presumably to indicate satiety at lower levels of food intake. In men, this decrease occurs when men reach a BMI classifying them as “overweight,” whereas women do not experience this drop in serotonin synthesis until reaching a BMI classifying them as “obese.”⁵

• Tumor necrosis factor alpha (TNF-alpha) is expressed in fat cells and is possibly involved in the development of insulin resistance. One variant of the gene for TNF-alpha is associated with obesity in women, but not in men.⁶

Obesity’s Effect on Women’s Health

• Obesity, especially abdominal obesity, is central to the metabolic syndrome and is strongly related to polycystic ovary syndrome (PCOS) in women. Obese women are particularly susceptible to diabetes and cardiovascular disease and have an increased risk of several major cancers in women, especially postmenopausal breast cancer and endometrial cancer.⁷

• Obese women who gain weight experience greater increases in blood pressure than their male counterparts.⁸

Leptin

• Leptin, a molecule produced by fat cells, is an important signal in the regulation of appetite and energy expenditure, and is thought to play a key role in the control of body weight. The level of leptin in the blood is correlated with BMI, and is far higher in women than men at every BMI level. This may be part of the reason why women are more likely than men to become overweight.^9-18

• Testosterone appears to play a large role in the regulation of leptin levels in the blood; men with higher testosterone levels have lower leptin levels.^{19, 20}

• Leptin levels rise in girls and fall in boys at puberty. The sex difference in leptin levels appears to be due to the increase in testosterone in boys and the increase in fat mass in girls at this developmental stage.^21-25

• Insulin resistance, which is thought to play a role in raising blood pressure, is correlated with blood leptin levels in men, but not in women.^{12, 26}

• Women who are pregnant with female fetuses experience significant increases in leptin levels during pregnancy, while women pregnant with male fetuses do not.²⁷

• Exercise appears to reduce blood leptin concentrations in women but not in men.²⁸

Weight Loss

• When losing weight, men are more likely to lose fat within the abdomen, whereas women are more likely to lose fat that resides just under the skin. Because of this difference, men experience greater declines in triglyceride levels and increases in HDL cholesterol (“good” cholesterol) levels compared to women losing the same amount of weight.²⁹

• The prevalence of attempting to lose and maintain weight is 28.8 percent and 35.1 percent among men and 43.6 percent and 34.4 percent among women, respectively, and among those attempting to lose weight, only 21.5 percent of men and 19.4 percent of women reported using the recommended combination of eating fewer calories and engaging in at least 150 minutes of leisure-time physical activity per week.³⁰

References
1. Obesity and Overweight: Frequently Asked Questions. Centers for Disease Control and Prevention. Available at: http://www.cdc.gov/nccdphp/dnpa/obesity/faq.htm; 2002.
2. Lovejoy JC. The influence of sex hormones on obesity across the female life span. J Womens Health. 1998;7(10):1247-1256.
3. Wardle et al., Am J Public Health 2002 Aug; 92(8):1299-1304.
4. Blaak, Curr Opin Clin Nutr Metab Care 2001 Nov;4(6):499-502.
Roca P, Proenza AM, Palou A. Sex differences in the effect of obesity on human plasma tryptophan/large neutral amino acid ratio. Ann Nutr Metab. 1999;43(3):145-151.
6. Hoffstedt J, Eriksson P, Hellstrom L, Rossner S, Ryden M, Arner P. Excessive fat accumulation is associated with the TNF alpha-308 G/A promoter polymorphism in women but not in men. Diabetologia. 2000;43(1):117-120.
7. Hu, J Womens Health 2003; 12(2):163-172.
8. Wilsgaard T, Schirmer H, Arnesen E. Impact of body weight on blood pressure with a focus on sex differences: the Tromso Study, 1986-1995. Arch Intern Med. 2000;160(18):2847-2853.
9. Hellstrom L, Wahrenberg H, Hruska K, Reynisdottir S, Arner P. Mechanisms behind gender differences in circulating leptin levels. J Intern Med. 2000;247(4):457-462.
10. Liuzzi A, Savia G, Tagliaferri M, et al. Serum leptin concentration in moderate and severe obesity: relationship with clinical, anthropometric and metabolic factors. Int J Obes Relat Metab Disord. 1999;23(10):1066-1073.
11. Ruige JB, Dekker JM, Blum WF, et al. Leptin and variables of body adiposity, energy balance, and insulin resistance in a population-based study. The Hoorn Study. Diabetes Care. 1999;22(7):1097-1104.
12. Sheu WH, Lee WJ, Chen YT. Gender differences in relation to leptin concentration and insulin sensitivity in nondiabetic Chinese subjects. Int J Obes Relat Metab Disord. 1999;23(7):754-759.
13. Morio B, Gachon AM, Boirie Y, et al. Lipolysis, fatness, gender and plasma leptin concentrations in healthy, normal-weight subjects. Eur J Nutr. 1999;38(1):14-19.
14. Licinio J, Negrao AB, Mantzoros C, et al. Sex differences in circulating human leptin pulse amplitude: clinical implications. J Clin Endocrinol Metab. 1998;83(11):4140-4147.
15. Sumner AE, Falkner B, Kushner H, Considine RV. Relationship of leptin concentration to gender, menopause, age, diabetes, and fat mass in African Americans. Obes Res. 1998;6(2):128-133.
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17. Niskanen LK, Haffner S, Karhunen LJ, Turpeinen AK, Miettinen H, Uusitupa MI. Serum leptin in obesity is related to gender and body fat topography but does not predict successful weight loss. Eur J Endocrinol. 1997;137(1):61-67.
18. Hickey MS, Israel RG, Gardiner SN, et al. Gender differences in serum leptin levels in humans. Biochem Mol Med. 1996;59(1):1-6.
19. Baumgartner RN, Ross RR, Waters DL, et al. Serum leptin in elderly people: associations with sex hormones, insulin, and adipose tissue volumes. Obes Res. 1999;7(2):141-149.
20. Elbers JM, Asscheman H, Seidell JC, Frolich M, Meinders AE, Gooren LJ. Reversal of the sex difference in serum leptin levels upon cross-sex hormone administration in transsexuals. J Clin Endocrinol Metab. 1997;82(10):3267-3270.
21. Ahmed ML, Ong KK, Morrell DJ, et al. Longitudinal study of leptin concentrations during puberty: sex differences and relationship to changes in body composition. J Clin Endocrinol Metab. 1999;84(3):899-905.
22. Roemmich JN, Clark PA, Berr SS, et al. Gender differences in leptin levels during puberty are related to the subcutaneous fat depot and sex steroids. Am J Physiol. 1998;275(3 Pt 1):E543-551.
23. Ambrosius WT, Compton JA, Bowsher RR, Pratt JH. Relation of race, age, and sex hormone differences to serum leptin concentrations in children and adolescents. Horm Res. 1998;49(5):240-246.
24. Garcia-Mayor RV, Andrade MA, Rios M, Lage M, Dieguez C, Casanueva FF. Serum leptin levels in normal children: relationship to age, gender, body mass index, pituitary-gonadal hormones, and pubertal stage. J Clin Endocrinol Metab. 1997;82(9):2849-2855.
25. Blum WF, Englaro P, Hanitsch S, et al. Plasma leptin levels in healthy children and adolescents: dependence on body mass index, body fat mass, gender, pubertal stage, and testosterone. J Clin Endocrinol Metab. 1997;82(9):2904-2910.
26. Sheu WH, Lee WJ, Chen YT. High plasma leptin concentrations in hypertensive men but not in hypertensive women. J Hypertens. 1999;17(9):1289-1295.
27. Helland IB, Reseland JE, Saugstad OD, Drevon CA. Leptin levels in pregnant women and newborn infants: gender differences and reduction during the neonatal period. Pediatrics. 1998;101(3):E12.
28. Hickey MS, Houmard JA, Considine RV, et al. Gender-dependent effects of exercise training on serum leptin levels in humans. Am J Physiol. 1997;272(4 Pt 1):E562-566.
29. Wirth A, Steinmetz B. Gender differences in changes in subcutaneous and intra-abdominal fat during weight reduction: an ultrasound study. Obes Res. 1998;6(6):393-399.
30. Serdula et al., JAMA 1999 Oct 13;282(14):1353-8.

Last updated: May 4, 2005