Underlying processes behind weight loss in overweight individuals following different energy-restricted dietspsychological, metabolomic and epigenetic mechanisms

Résumé

The rates of non-communicable diseases have reached epidemic proportions worldwide, with obesity and psychological disorders being among the most prevalent. The main purpose of this research was to determine the possible metabolic and epigenetic mechanisms behind weight loss in overweight individuals after following different energy-restricted diets, as well as evaluating the impact of the dietary treatments on symptoms of depression and anxiety disorders. To follow a hypocaloric diet designed to reduce metabolic syndrome (MetS) features was effective for decreasing depressive and anxiety symptoms in middle-aged subjects. The decrease in depressive manifestations was positively related to body weight and fat mass changes, as well as with the decrease in C-reactive protein (CRP), malondialdehyde (MDA) and leptin blood levels and with a higher folate intake during the intervention. In contrast, decline in anxiety symptoms was parallel to a greater decrease in body weight, body mass index (BMI), waist circumference and fat mass. Moreover, a positive cross-sectional association between a healthy dietary pattern and intake of some specific nutrients (water, fibre, vitamin B6, ascorbic acid, tryptophan, magnesium and selenium) with mood state was found. In addition, a negative relationship between depressive symptoms and consumption of omega-3 polyunsaturated fatty acids (PUFAs) was evidenced in middle-aged subjects with MetS. Interestingly, an increase in serotonin and dopamine (DA) blood levels after the weight loss treatment in obese patients with MetS was demonstrated, being this increase related with lower energy and carbohydrates intakes, respectively. Furthermore, in overweight and obese older adults baseline palmitoleic acid (C16:1) concentrations were found to be negative predictor of changes in adiposity, while baseline DA and serotonin receptor 2A (HTR2A) methylation levels were hypothesized as new biomarkers for the response to a nutritional intervention in subjects with MetS. In summary, this thesis provides further insights regarding emotional and metabolic factors behind body weight reduction after following different dietary treatments for weight loss in overweight and obese older adults as well as in middle-aged subjects with MetS.