PURPOSE: This study examines the relationship of changes in body mass index (BMI) to changes in measures of both casual and ambulatory blood pressures over three years.

METHODS: In this prospective study of men aged 30-60 years, a cohort of 198 participants was followed for three years. Height, weight, demographic characteristics, and casual and ambulatory measures of blood pressure (BP) were obtained at baseline and 3-year follow-up.

RESULTS: Change in BMI was significantly associated with change in all ambulatory (awake, work, home, and sleep) and casual systolic and diastolic blood pressures. After controlling for age and race/ethnicity, the association remained significant for nine of the twelve BP change measures. Further tests show that the effect of a change in BMI on BP change does not vary across the six systolic blood pressures or across the six diastolic measures. An average-height man gaining 5 kg (11 pounds) typically exhibited a 2.5 mm Hg increase in systolic and a 1.8 mm Hg increase in diastolic casual and ambulatory BPs. There is no evidence that changes in BP were associated with age, race/ethnicity (blacks vs. Hispanics vs. whites), or the average of the baseline and follow-up levels of BMI. In addition, the impact of weight gain is similar in magnitude, but in the opposite direction, to that of weight loss.

CONCLUSIONS: Changes in BMI over three years predict changes in ambulatory and standardized non-physician BPs. These changes in BP are not related to average BMI level or age