Dietary fat intake and obesity : an empirical study in Greek adults
The empirical evidence concerning the associations between diet, particularly fat intake, and obesity is inconclusive. The aim of the present study was to investigate cross-sectional associations between general and central adiposity, and dietary and other socio-demographic and behavioural factors influencing energy balance. Study subjects were 961 women and 596 men aged 30-75 years who participated in the Greek segment of the European Prospective Investigation into Cancer and Nutrition (EPIC) Study. General obesity was evaluated by Body Mass Index (BMI) and central obesity by Waist to Hip ratio (WHR) and Waist Circumference (WC). Dietary intake was estimated through a validated semi-quantitative Food Frequency Questionnaire (FFQ) obtained at baseline. Time weighted occupational and leisure activities, as well as socio-demographic and behavioural data were assessed through a life-style questionnaire. The methodological issues related to under-reporting and adjustment for energy intake have been considered in depth. Obesity indices (BMI, WHR, WC) were initially regressed, separately for men and women, on energy intake and energy expenditure, after adjusting for the confounding effects of age, socio-economic status and smoking habits and controlling for dietary under-reporting. Results indicated that increasing physical activity is less effective than decreasing energy intake in reducing BMI. WHR and WC were not affected by energy intake, whilst energy expenditure reduced WHR and WC independently of BMI. Obesity indices (BMI, WHR, WC) were subsequently regressed on nutrient intake after controlling for the confounding effects of energy intake, energy expenditure, age, socio- economic status and smoking habits, including and excluding under-reporters of energy intake. Among women, but not men, the nutrient more strongly positively associated to BMI was protein and to a lesser extent mono-unsaturated and total fat intake. WHR and WC do not seem to be differentially affected by energy equivalent amounts of energy generating nutrients.