Overweight and Obesity in Women: Health Risks and Consequences

Frank B. Hu, M.D., Ph.D.

Disclosures
In This Article

Obesity and Risk of Diabetes, CVD, and other Chronic Diseases

Excessive body weight increases the risk of diabetes, CHD, and cholelithiasis in both women and men.[46] In general, the relationship between BMI and type 2 diabetes and CHD is stronger for women than for men (Fig. 1). Comparing a BMI of 26 with a BMI of _21, the relative risks (RRs) of diabetes were about 8 for women and 4 for men. The corresponding RRs for CHD were 2 for women and 1.5 for men. In the Nurses' Health Study,[47] the single most important risk factor for type 2 diabetes was over-weight and obesity. The RRs were 38.8 for _35 kg/m2 and 20.1 for 30.0-34.9 kg/m2 compared with <23 kg/m2 . Even a BMI within the normal range (23-24.9 kg/m2 ) substantially elevated the risk (RR = 2.67). In this cohort of women, 61% (95% CI 58-64) of type 2 diabetes cases could be attributed to overweight and obesity (using 25 kg/m2 as a cutoff point). Using as a reference women with a BMI of <21 kg/m2 , the RRs and 95%CIs for CHD were 1.19 0.97-1.44) for a BMI of 21-22.9 kg/m2 , 1.46 (1.20-1.77) for a BMI of 23-24.9 kg/m2 , 2.06 (1.72-2.48) for a BMI of 25-28.9 kg/m2 , and 3.56 (2.96-4.29) for a BMI of _29 kg/m2.[48] These data suggest that higher levels of body weight within the normal range increase risks of CHD in middle-aged women.

Relation between BMI _ 30 and the RR of type 2 diabetes, hypertension, CHD, and cholelithiasis. (A) Relations for women in the Nurses' Health Study, initially 30-55 years of age, who were followed for up to 18 years. (B) Relations for men in the Health Professionals Follow-up Study, initially 40-65 years of age, who were followed for up to 10 years. (From Willett et al. N Engl J Med 1999;341:427.46)

Abdominal obesity assessed by waist circumference or WHR predicts risk of diabetes and CHD independent of BMI. As with BMI, waist circumference or WHR appears to be a stronger predictor of diabetes in women[49] than in men[50] (Fig. 2). In the Nurses' Health Study,[49] controlling for BMI and other potentially confounding factors, the RR for the 90th percentile of WHR (WHR = 0.86) vs. the 10th percentile (WHR = 0.70) was 3.1 (95% CI 2.3-4.1), and the RR for the 90th percentile of waist circumference (36.2 inches or 92 cm) vs. the 10th percentile (26.2 inches or 67 cm) was 5.1 (95% CI 2.9-8.9). Higher WHR and greater waist circumference were also independently associated with a significantly increased risk of CHD in women.[51] After adjusting for BMI and other cardiac risk factors, women with a WHR of $0.88 had an RR of 3.25 (95% CI, 1.78-5.95) for CHD compared with women with a WHR of <0.72. A waist circumference of _96.5 cm (38 in) was associated with an RR of 3.06 (95% CI, 1.54-6.10). In addition, the WHR and waist circumference were independently strongly associated with increased risk of CHD among women with a BMI of _25 kg/m2.

RRs of type 2 diabetes according to categories of waist circumference in women and men. (Adapted from Carey et al. Am J Epidemiol 1997;145:614,49 and Chan et al. Diabetes Care 1994;17:1.50)

Weight gain, even at modest level (e.g., <10 kg), during adulthood is associated with risk of diabetes, CHD, and other chronic diseases independent of initial body weight, and the increased risk appears to be somewhat greater for women than for men (Fig. 3).[46] In the Nurses' Health Study,[52] compared with women with stable weight (those who gained or lost <5 kg between age 18 years and 1976) and after adjustment for age and BMI at age 18 years, the RR for diabetes among women who had a weight gain of 5.0-7.9 kg was 1.9 (95% CI, 1.5 to 2.3). The corresponding RRs were 2.7 (95% CI 2.1-3.3) for women who gained 8.0-10.9 kg and 12.3 (95% CI, 10.9 to 13.8) for those who gained $20.0 kg. In contrast, women who lost >5.0 kg reduced their risk for diabetes mellitus by 50% or more. With respect to risk of CHD,[48] compared with those with stable weight, the RRs were 1.25 (1.01-1.55) for a 5-7.9-kg gain, 1.64 (1.33-2.04) for an 8-10.9-kg gain, 1.92 (1.61-2.29) for an 11-19-kg gain, and 2.65 (2.17-3.22) for a gain of _20 kg. Among women with the BMI range of 18-25 kg/m2 , weight gain after 18 years of age remained a strong predictor of CHD risk. These results suggest that modest weight gains after 18 years of age strongly predict increased risks of CHD in middle-aged women.

Relation between change in weight and the RR of type 2 diabetes, hypertension, CHD, and cholelithiasis. (A) Relations for change of weight from 18 years of age among women in the Nurses' Health Study, initially 30-55 years of age, who were followed for up to 18 years. (B) Relations for change of weight from 20 years of age among men in the Health Professionals Follow-up Study, initially 40-65 years of age, who were followed for up to 10 years. (From Willett et al. N Engl J Med 1999;341:427.46)

Obesity is also associated with the incidence of several major cancers, including postmenopausal breast cancer and cancers of the colon, endometrium, and kidney.[53] In the Nurses' Health Study,[54] weight gain after the age of 18 years was unrelated to breast cancer incidence before menopause but was positively associated with incidence after menopause. This increased risk with weight gain was limited to women who never used postmenopausal hormones. Among these women, the RR was 1.99 (95% CI, 1.43-2.76) for weight gain of >20 kg vs. unchanged weight (p for trend <0.001). In this population, the percentage of postmenopausal breast cancer accounted for by weight gain alone was approximately 16% and by hormone replacement therapy (HRT) alone was 5%. These results suggest that avoiding adult weight gain may contribute importantly to the prevention of breast cancer after menopause.

In addition, obesity is associated with increased risk of stroke,[55] osteoarthritis,[56] asthma,[57] and sleep apnea[58] in women. Moreover, weight gain in women is associated with decreased physical function and vitality and increased bodily pain regardless of baseline weight.[59] In contrast, weight loss in overweight women is associated with improved physical function and vitality as well as decreased bodily pain. Furthermore, increased BMI at age 18, even at levels lower than those considered to be obese, is an important risk factor for subsequent ovulatory infertility.[60]

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as:

processing....