Study of the Effects of Time-Restricted Feeding on the Immune Function of Individuals with Obesity

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


Eligibility Criteria:
Inclusion Criteria:

Patients with obesity

* Women
* Age 18-64 years
* Body mass Index between 40-50 kg/m²
* Scheduled bariatric surgery 10-12 weeks after the nutritional intervention
* Self-reported eating pattern window of more than 14h
* Three meal eating pattern
* Stable body weight (less than 10% of current body weight during the last 3 months)
* Patients who have a favorable decision from the multidisciplinary team meetings after multidisciplinary nutritional follow-up of at least 6 months and history of failure with non-surgical weight loss methods
* Social security affiliation
* Written consent
* Good understanding of the Catalan or Spanish languages

Exclusion Criteria:

* Diabetes type I or II
* Major cardiovascular disease
* Pregnancy
* Medication that could affect the study outcomes (i.e. anti-inflammatory drugs, antibiotics, immunosuppressors)
* Use products intended for weight loss
* Night work shift
* Past record of malignant tumors
* Serious liver dysfunction or chronic kidney disease
* Eating disorders
* Chronic viral disease (Hepatitis B or C, HIV) or inflammatory systemic diseases (i.e. Crohn's disease, rheumatoid arthritis)
* Serious cardiovascular or cerebrovascular disease within 6 months before randomization
* Severe gastrointestinal diseases or gastrointestinal surgery in the 12 months before randomization
* Under guardianship, curatorship, deprived of liberty
* Unable or unwilling to sign the informed consent form.