Dietary weight loss decreases serum angiotensin-converting enzyme activity in obese adults.

OBJECTIVE

To study the effect of dietary weight loss, postural change, and an oral glucose load on serum angiotensin-converting enzyme (ACE) activity in obese adults.

RESEARCH METHODS AND PROCEDURES

Sixteen obese adult men and women with a mean body mass index of 35.7 +/- 4.3 kg/m(2) were studied after 1 week on a maintenance energy lead-in diet and after 5 weeks on an identical but 40% reduced-energy diet provided by the General Clinical Research Center (GCRC). ACE activity was measured spectrophotometrically. Plasma renin activity and serum aldosterone were measured by radioimmunoassay.

RESULTS

All subjects lost weight, with a mean decrease in body weight of 7.0 +/- 2.1 kg or 6 +/- 3% of initial body weight (p < 0.00001). Systolic and diastolic blood pressure, supine plasma renin activity, and serum aldosterone levels decreased with weight loss (p < 0.05). Supine ACE activity decreased 23 +/- 12% with weight loss (p < 0.00001). Standing ACE activity, which was significantly higher than supine ACE activity before and after weight loss (p < 0.05), also decreased 18 +/- 17% with weight loss (p = 0.0007). A 75-g oral glucose load had no effect on serum ACE activity over a 3-hour period.

DISCUSSION

In obese adults, serum ACE activity declines with modest weight loss, increases with postural change, and is unaffected by an oral glucose load.