The goal of this randomized trial is to: 1) investigate the immunological landscape of patients with obesity and conduct an in-depth functional characterization of their immune system; and 2) precisely define the effects of time-restricted feeding (TRF) on immune function in patients with obesity; 3) define the immunomodulatory properties of white adipocytes in response to TRF, and 4) uncover the underlying mechanisms by which TRF modulates the immune system patients with obesity through a multi-omics approach. The main questions it aims to answer are: i) what is the underlying cause of impaired immunocompetence in patients with obesity? ii) how nutritional interventions improve the immune function of patients with obesity? Patients with obesity following TRF (8 h eating window ranging from 6-8 am to 14-16 pm) will be compared to patients with obesity without TRF control schedule (14h eating window ranging from 6-8 am to 8-10 pm). The dietary intervention will begin 10 weeks before the scheduled date for bariatric surgery in patients with obesity. In addition to patients with obesity, the present study aims to recruit a group of a reference healthy group (BMI between18.5-24.9 kg/m²) that will not receive any nutritional intervention. The following endpoints will be collected: Body weight and composition using Bioelectrical Impedance Analysis, resting energy expenditure (REE) using indirect calorimetry, blood glucose levels using a continuous glucose monitoring (CGM) device, metabolic parameters (fasting blood glucose levels, C-peptide, HbA1c, insulin, HOMA-IR, total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, hepatic enzymes), and cytokine profile. Blood, stool, and white adipose tissue (WAT) samples will be collected to establish metagenomic, transcriptomic, cytomic and metabolomic analyses