Follow-up of two personalized energy-restricted dietary strategies in subjects with nonalcoholic fatty liver disease: underlying nutritional and lifestyle factors

Nonalcoholic fatty liver disease (NAFLD) prevalence is estimated around 25% worldwide being related to the growing rates of obesity, type 2 diabetes mellitus, and cardiovascular disease. NAFLD onset and progression are complex and have shown relationships with multiple environmental contributors, including unbalanced diets. A link between NAFLD and some psychological traits and inadequate sleep has been suggested, but the nature of these relationships is poorly understood. The current management of NAFLD relies on lifestyle modifications that promote weight loss by means of changes in the diet and/or physical activity. In this context, this research had the following objectives: 1) To evaluate the long-term effects of two personalized energy-restricted dietary strategies on weight loss, anthropometric measurements, biochemical determinations, and hepatic status in subjects with overweight or obesity and NAFLD within a follow-up of 24 months (Chapter 1); 2) To assess the potential relationships of different nutritional factors with hepatic outcomes of individuals with overweight or obesity and NAFLD following personalized energy-restricted dietary strategies (Chapter 2 and 3); 3)To analyze the potential relationships between well-being factors including psychological traits and sleep features with hepatic health markers of individuals with overweight or obesity and NAFLD (Chapter 4 and 5). Regarding the first objective, the results suggested that both dietary strategies may be suitable alternatives for NAFLD management. However, the Fatty Liver in Obesity strategy seemed to provide greater and more persistent metabolic and hepatic benefits. In relation to the second objective, the decrease in liver fat content was associated with a greater weight loss and a higher adherence to the Mediterranean Diet (MedDiet) and dietary Total antioxidant capacity (TAC) after 6 months of intervention. Moreover, the adherence to dietary strategies for 6 months led to changes in erythrocyte membrane omega-3 fatty acid composition, which in turn were associated with changes in hepatic markers (liver stiffness and liver iron content). Concerning the third objective, dietary strategies produced benefits not only in hepatic status but also in depressive and anxiety symptoms, which were positively associated with anthropometric and hepatic determinations. In addition, NAFLD subjects showed poorer sleep features compared to non-NAFLD controls. Likewise, higher sleep disturbances were associated with more probability of having NAFLD, while more sleep disturbances and worse sleep quality were associated with higher values of liver stiffness in NAFLD subjects. In conclusion, healthy energy-restricted dietary strategies with high adherence to MedDiet, as well as TAC and omega-3 fatty acids seem to be effective to improve different metabolic and hepatic markers in subjects with NAFLD. Moreover, beneficial effects on depressive and anxiety symptoms are promoted with these approaches fostering improvements in overall health. In addition to dietary factors, psychological traits and characteristics of sleep pattern should receive attention in the design and implementation of strategies for the prevention and management of NAFLD