Considerations on the dynamics of adipose cells in relation to ponderal variations: morphoquantitative aspects

The sizes and numbers of subcutaneous adipose-tissue fat cells were determined in obese patients, some of whom had undergone severe weight reduction induced by a jejuno-ileal bypass operation, and others a moderate thinning by a reducing diet, for comparison with those in normals. The size-class distribution of the fat cells suggests a morphoquantitative, dynamic interpretation of the two known forms of obesity, one being of moderate degree and called hypertrophic, the other more severe and called hyperplastic. The hypertrophic obese condition is characterized by a bimodal size-distribution curve of the adipocytes, similar to the curve in normal individuals. In both the normal and the hypertrophic obese, ponderal variations displace this curve forwards or backwards without altering its shape. By contrast, the hyperplastic obese shows a flat size-distribution curve without discernible modes. The smallest size-class of fat cells are the most sensitive to weight-reduction process and hypotrophize so much that they can no longer be recognized as adipocytes in histological sections; thus the size-distribution curve for hyperplastic obese individuals losing weight changes in shape from uniform to bimodal. The relationship which expresses the mean fat cell diameter as a function simultaneously of the initial weight and of ponderal variation was also studied, and tested by multiple regression analysis.