Anthropometric, metabolic and immunological factors in overweight/obesity and their influence on the responsiveness to a nutritional intervention for body weight management.

Obesity is a public health concern that presents considerable difficulty in its management. Efforts are extensive to discover and develop new strategies to reduce body weight and fat accumulation. A group of plant-derived chemicals, known as polyphenols and with recognised anti-oxidant and anti-inflammatory properties, have been suggested as potential candidates to aid weight loss and management. On the other hand, great variability is observed in the individual responsiveness to weight-loss treatments; a multitude of factors, both physiological and environmental, may contribute to this variability, but their specific contributions are not properly understood. This project aimed to explore the relationships between obesity and selected lifestyle factors, metabolic and immunological markers, and to analyse the effect of a polyphenol-based weight-loss intervention, assessing individual responsiveness and determining potential predictors of weight loss. This project studied 79 men and women (≥18 years; 39.8% women) classified as overweight or obese, who received drinks containing polyphenol-rich extracts, in a placebo-controlled, double-blind, crossover intervention. In a first stage, the associations between anthropometric indices and the above mentioned blood factors were analysed. Baseline and post-treatment values for all variables were then compared. Finally, participants were classified into tertiles according to their relative post-treatment body weight change into high (≥1.5% initial weight loss) or low (any weight gain) respondents; those who neither lost nor gained weight were excluded from the analysis. The participants’ baseline characteristics were compared, and the correlations between body weight change and the different markers studied were analysed, in order to identify potential predictors for subsequent regression analysis. Obesity markers in our sample were linked to higher levels of metabolic syndrome and inflammation markers. The polyphenol-based treatment (B2) were associated with small but significant reductions in body mass index (BMI) in women, reductions in specific white blood cell subsets counts (white blood cell counts and neutrophil, total T helper cells (CD4+), naive T helper cells (CD4+RA+) counts), increased red blood cell haemoglobin concentration and levels of circulating non-esterified fatty acids. Body fat %, anthropometric indices, and all other blood variables analysed did not change significantly in response to the treatments. There was large variability in relative body weight change post-treatment (-4.63% to + 3.93%). High respondents presented lower baseline values for the obesity indices (BMI and WHeR), T naïve (CD8+RA+) counts and interleukin-6 (IL-6). Relative body weight change was negatively correlated with blood levels of triglycerides, very low-density lipoprotein- 4 cholesterol (VLDL-cholesterol) and granulocyte-macrophage colony-stimulating factor (GM-CSF). A regression model including compliance with the treatment, triglycerides and BMI explained 18.1% of the variability in weight change (P=0.003). In women only, compliance and GM-CSF explained 30% of the variability (P=0.040), and in men, B cell (CD19+) count and BMI explained 13.6% of the variability (P=0.047). In conclusion, Future work is needed to study the contribution of lifestyle factors, in particular physical activity and dietary composition, to the responsiveness to the present treatment. Research in the field of personalised nutrition will allow a more streamlined approach to weight loss and contribute to manage the current obesity epidemic.