Central obesity is characterized by low-grade chronic inflammation that is mirrored by alterations of the microenvironment of the visceral adipose tissue. The objective of the present study is to explore the effects of different eating,sleeping, and physical activity pattern and dietary regimens i.e. low-calorie ketogenic diet (LCKD) and low-calorie balanced nonketogenic diet (LCD) - in obese patients proposed for diet therapy or bariatric surgery (Sleeve Gastrectomy) on inflammatory (ESR, CRP, ferritin, white blood cells count ), immunitary (AntiSARS-CoV-2 IgG and IgM, Cell mediated response to SARS CoV-2, lymphocyte and monocyte subpopulations, cytokines) and metabolic (glucose, insulin, lipid profile) indices, on circulating PBMC (peripheral blood mononuclear cells) gene expression Furthermore, in patients undergoing bariatric surgery, the morpho-functional characteristics of the visceral adipose tissue and the polarization of the resident macrophages will be analyzed. The results of this study will allow to define the characteristics of the immune-inflammatory derangement of complicated obesity and to identify therapeutic targets and strategic paths related to the immuno-metabolic aspects closely related to the visceral obesity phenotype that predispose to severe forms of COVID 19. These investigations will provide a detailed and mechanistic evaluation of the effects of different types of eating, sleeping and physical activity pattern (with particular attention to KD), and of bariatric surgery on inflammatory, metabolic and body composition parameters. The comparative study of tissue macrophage polarization with lymphocyte subpopulations and the typing and gene expression of circulating monocytes will provide information on the potential role of monocytes as peripheral indicators of adipose tissue alterations and of therapeutic efficacy
