The association between obesity and hypertension has been clearly demonstrated. Short-term weight loss appears to reduce blood pressure in patients with hypertension. The degree to which long-term weight reduction prevents or delays the onset of hypertension is less clear. Huang and associates investigated the effect of long-term and medium-term weight changes in a cohort of women without diagnosed hypertension at baseline.

The Nurses' Health Study is a long-term follow-up study of nurses who were 30 to 55 years of age at the time of study entry in 1976. Questionnaires were sent every two years to identify diagnoses of hypertension and other medical events and to measure risk factors. Body mass index (BMI) was used as a measure of obesity. Women were divided into nine groups based on amount of weight gain or loss. The stable weight group was used as the baseline. Incidence of hypertension was determined by self-report of high blood pressure as diagnosed by a physician. A total of 16,395 cases of hypertension were diagnosed in the cohort of 82,473 women.

Higher current BMI was strongly associated with an increasing risk for hypertension. Women with a BMI of 31 kg (68.2 lb) per m² had a relative risk of 6.31 of being diagnosed with hypertension. An increase in BMI of 1 kg (2.2 lb) per m² was associated with a 12 percent increase in risk for hypertension. Higher BMI at 18 years of age was associated with an increased risk for hypertension later in life. Risk of hypertension was reduced by 15 percent with a weight loss of 5 to 9.9 kg (11 to 21.78 lb) and by 26 percent for a weight loss of 10 kg (22 lb) or more. Both attained BMI and history of weight changes appeared to be independent predictors of risk for hypertension.

The authors conclude that higher BMI at age 18 appears to be associated with later development of hypertension, while higher BMI at midlife appears to be even more strongly associated. Long-term and medium-term weight loss were associated with a substantially reduced risk for subsequent hypertension. Sustained weight loss appears to have a stronger protective effect. This association is strongest in women with a higher baseline BMI. Weight loss in women who are already overweight appears to be an effective strategy for reducing the risk of hypertension.

editor's note: We have known for a long time that overweight persons with hypertension may lower their blood pressure by losing weight. The current study now defines weight reduction as a primary prevention method against the development of hypertension. This appears to be true in persons with or without a family history of hypertension. In our discussions with overweight patients about the potential complications of their weight, talking about hypertension allows a powerful “teachable moment” to emphasize the value of weight reduction.—r.s.