Endocrine, metabolic and nutritional factors in obesity and their relative significance as studied by factor analysis

To evaluate different aspects of obesity, such as body fat distribution, plasma hormone and lipid profiles, adipose tissue composition and dietary intake in an obese population in order to identify the most important factors that contribute to obesity.

Eighty-five obese subjects, 30 men and 55 women (age, 30-70 y; body mass index (BMI), 27-35 kg/m2), were studied using anthropometric measurements, computed tomography, adipose tissue composition, serum hormone and lipid profiles and nutritional evaluations. To determine to what extent individual factors contributed to the general process of obesity, the data were subjected to a factor analysis.

Three patterns of anthropometric and computed tomography data emerged that accounted for 69% of the variance. Factor 1 defined abdominal obesity and explained 30% of the total variance, factor 2 (gynoid obesity) accounted for 26%; and factor 3 (subcutaneous fat) explained 13% of the total variance. When other factors associated with obesity, such as lipid profile, hormonal profile and fat composition, were introduced, obesity itself, especially abdominal obesity, remained the principal factor, accounting for 23% of total variability. All factors were of secondary importance when dietary characteristics were introduced. In the overall factor analysis, more than 40% of the variability in obesity was related to dietary habits, particularly fat intake, followed by energy and saturated fatty acids intake.

Even though obesity is a multifactorial phenomenon, the results suggest that dietary intake, especially fat intake, is the most important factor contributing to obesity. Secondary factors include endocrine and metabolic factors.