Abstracts

The relationship of body fat distribution with blood pressure, fat cell weight and extracellular fluid volume was studied and compared in 20 obese hypertensive men and 20 obese hypertensive women of similar age, degree of overweight and blood pressure level. Body fat distribution, as reflected by the ratio between waist and hip circumference (W/H ratio), was significantly higher in male than in female obese patients. The W/H ratio was positively and independently correlated with systolic arterial pressure both in males and females. However, for the same W/H ratio, systolic arterial pressure was higher in females. The W/H ratio was positively correlated with gluteal fat cell weight only in males and not in females. Both in males and females, the W/H ratio was positively correlated with extracellular fluid volume, independently of the level of blood pressure level and/or the degree of obesity. The study provided evidence that the relationship between body weight and blood pressure in obese hypertensives is affected by the sex-dependence of body fat distribution with possible interferences on fat cell weight and extracellular fluid volume.

Several epidemiological studies have emphasized the positive correlation observed between body weight and blood pressure in man (1-4). Many investigations have documented the association of blood pressure with body weight, weight to height, overweight or other indices of fatness such as skinfold thickness (1-6). However, the correlation coefficients of these different relationships were found constantly small, indicating that the relationship between overweight and blood pressure is somewhat complex.

In patients with hypertension, body weight was shown to be strongly related with the levels of both blood pressure and extracellular fluid volume (7-9). On the other hand, patients with overweight and hypertension were found to be principally affected by hypertrophic obesity, as shown by the evaluation of fat cell weight (10). However these findings were exclusively observed in males. No solid data were reported in females.

The relationships between body weight and extracellular fluid on one hand, and between body weight and fat cell weight on the other hand, are certainly different in males and in females. First, in females, extracellular fluid volume is submitted to cyclic changes in sodium balance involving the effect of sex steroid hormones (1, 7, 11). Second, body fat distribution, a parameter which is weakly correlated to blood pressure (2, 11, 12), is different in males and females. In males, body fat predominates in the upper part of the body while, in females, adiposity is mainly observed in the lower part of the body (5). In that regards, it is important to investigate body fat distribution in males and females with obesity and hypertension, with reference to the most important parameters involved in body weight composition : fat cell weight and extracellular fluid volume.