The Effects of Weight Loss on Blood Pressure

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The summary below is from the full report titled "Long-Term Weight Loss and Changes in Blood Pressure: Results of the Trials of Hypertension Prevention, Phase II." It is in the 2 January 2001 issue of Annals of Internal Medicine (volume 134, pages 1-11). The authors are VJ Stevens, E Obarzanek, NR Cook, I-M Lee, LJ Appel, D Smith West, NC Milas, M Mattfeldt-Beman, L Belden, C Bragg, M Millstone, J Raczynski, A Brewer, B Singh, and J Cohen.

What is the problem and what is known about it so far?

High blood pressure (hypertension) puts people at risk for heart attacks and strokes. Being overweight contributes to hypertension. It is well known that overweight persons with hypertension can lower their blood pressure by losing weight. It is not known, however, whether weight loss will lower blood pressure or prevent hypertension in overweight adults whose blood pressure is on the high side of normal to begin with. Normal blood pressures are less than 140/90 mm Hg. The first number is called systolic blood pressure, and the second number is called diastolic blood pressure.

Why did the researchers do this particular study?

To find out whether blood pressure decreases in overweight adults with high-normal blood pressure who lose weight.

Who was studied?

The study included 1191 adults 30 to 40 years of age who weighed 10% to 65% more than their ideal body weight and had high-normal blood pressure (a systolic blood pressure less than 140 mm Hg and a diastolic blood pressure of 83 to 89 mm Hg).

How was the study done?

The researchers used information, taken from a larger study on hypertension, on 595 patients assigned to a weight loss program and 596 patients assigned to a "usual care" control group. The weight loss program involved 3 years of regular group meetings and individual counseling that focused on diet, physical activity, and social support. Usual care control patients received regular medical care with no special treatment to encourage weight loss. The researchers measured weight and blood pressure every 6 months for 3 years in all patients.

What did the researchers find?

At 6, 18, and 36 months, participants in the weight loss program had lost an average of 4.4, 2.0, and 0.2 kg, respectively, whereas participants in the usual care group had gained 0.1, 0.7, and 1.8 kg. (One kilogram equals about 2.5 pounds.) Although not all participants assigned to the weight loss group lost weight, those who did had favorable decreases in blood pressure. Patients who lost at least 4.5 kg (10 pounds) over 3 years had the biggest reduction in blood pressure compared with controls.

What were the limitations of the study?

More than three quarters of the study participants were white, more than two thirds were men, and half were college graduates. It is uncertain whether these results apply to persons with other characteristics. Despite the intensive program, the number of persons who maintained substantial weight loss was modest.

What are the implications of the study?

When overweight persons with high-normal blood pressure lose weight, blood pressure becomes lower. Weight loss in this group also decreases the chances that hypertension will develop.