Fasting Mimicking Diet and Beige/Brown Adipose Tissue in Humans

HYPOTHESIS

Beige/BAT has been shown as a promising strategy to treat obesity. The exact mechanism, and stimulus, of activation of this tissue have not been completely clarified. However, some studies have identified some nutrients, such as unsaturated fat, as a potential stimulus for activation. The effect of Fasting Mimicking Diet on the activation of Beige/Brown Adipose Tissue has not yet been investigated. Since FMD is high in unsaturated fat, and clinical trials have shown that FMD interventions reduced body weight and improved metabolic health, there is a possible association between this diet and the activation of beige/BAT.

Our hypothesis is that an intervention, with a 5-days cycle for 3 consecutive months, of Fasting Mimicking Diet will promote beige/brown adipose tissue activation and will improve body weight and metabolic markers related to obesity, in humans with overweight.

OBJECTIVES

Main Objective

To evaluate the effect of a dietary intervention using 3 cycles of Fasting Mimicking Diet on the activation of beige/brown adipose tissue, in humans with overweight.

Specific Objectives

- To evaluate the effect of the FMD on the activation of Beige/Brown Adipose Tissue using PET/CT (FDG-18) and Thermal Imaging (FLIR camera);

- To evaluate anthropometric measures (weight, abdomen circumference) and body composition (DEXA scan), before, during and after the FMD intervention;

- To evaluate basal metabolic rates and daily caloric needs (Indirect Calorimetry), before and after the FMD intervention;

- To evaluate the effect of the FMD on metabolic markers and hormones: leptin (ELISA), insulin (ELISA), glucose, total cholesterol, LDL, HDL and triglycerides;

- To evaluate the effect of the FMD on insulin sensitivity (using OGIS);

- To evaluate the effect of the FMD on cytokines: tumor necrosis factor alpha (TNF-α), interleukin 1-beta (IL1β), Monocyte Chemoattractant Protein-1 (MCP1), interleukin-6 (IL-6) and interleukin-10 (IL-10) (ELISA);

- To evaluate the effect of the FMD on Brown Adipose Tissue Adipokines: insulin-like growth factor 1 (IGF-1), IL-6, fibroblast growth factor 21 (FGF21) and 12,13-dihydroxy-9z-octadecenoic acid (12,13-diHOME) (ELISA);

- To evaluate the effect of the FMD on BAT activation genes: peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and G-protein coupled receptor 120 (GPR120) (PCR).

MATERIALS AND METHODS

Selection of Participants

The estimated sample size is 26 individuals. Participants will be overweight. There will be a control group (n=13) and an FMD group (n=13). There will be similar sample size for both genders. Participants will be recruited through electronic and printed media propagation.

Design

This will be an open clinical trial with the duration of three consecutive months (three cycles). There will be data collection before, during and after the dietary intervention. In this intervention, participants will be requested either to follow three cycles of a Fasting Mimicking Diet, or to follow their habitual eating habits for three months (control group). For the FMD group, participants will receive the FMD diet and will be requested to follow the recommendations from the manufacturer: FMD diet for 5 consecutive days (during these days, they will be asked to only eat the FMD diet), and for the remaining 25 days of the month, participants should continue with their habitual eating habits. This procedure will be repeated three times.

The FMD diet will be provided by L-Nutra, Nutrition for Longevity (commercial name of the diet: ProLon). All the data will be collected at University of Campinas, Brazil. More specifically, the Indirect Calorimetry and the DEXA scan will be done at the LIMED (Laboratory of Investigation of Metabolism and Diabetes) and the PET/CT (FDG-18) will be done at the Center of Nuclear Medicine in the Hospital de Clínicas (HC) Hospital.

The following data will be collected from both groups (control and FMD):

- Evaluation of food consumption: 24hr-Food Recall - before, during and after the intervention;

- Evaluation of physical activity: short version of the International Physical Activity Questionnaire IPAQ) - before and after the intervention;

- Evaluation of beige/BAT activity:

- Positron Emission Tomography (PET) with fluoride-18-labeled fluorodeoxyglucose (18F-FDG) in combination with computed tomography (PET/CT scan) - before and after the intervention:

- Individualized cooling protocol: For this exam, participants will be allocated in a room with a controlled temperature (19oC). They will be using light cloths and a cooling vest (commercial name: Polar), for one hour. Right after, they will receive 4.0 megabecquerel/kg (MBq/kg) of 18F-FDG and will continue in the room, with a controlled temperature (19oC), for another hour. After these two hours they will move to the PET/CT room;

- Thermal Imaging (FLIR camera) - before, during and after the intervention:

- Individualized cooling protocol: For this exam, participants will be allocated in a room with a controlled temperature (19oC). They will be using light cloths and a cooling vest (commercial name: Polar), for two hours;

- Brown Adipose Tissue Adipokines: IGF-1, IL-6, FGF21 and 12,13-diHOME, using ELISA;

- Brown Adipose Tissue activation genes: PGC-1α and GPR120, using PCR;

- Evaluation of basal metabolic rates and caloric needs: Indirect Calorimetry (gas exchange analysis: oxygen (O2) consumption and carbon dioxide (CO2) release) - before and after the intervention;

- Evaluation of anthropometric measures - before, during and after the intervention:

- Weight (digital scale) and height (fixed stadiometer);

- Abdominal circumference;

- Body composition: Dual-energy X-ray absorptiometry (DEXA scan);

- Blood samples - before, during and after the intervention:

- Cytokines (TNF-α, IL1β, MCP1, IL-6 and IL-10) and hormones (insulin and leptin) - Enzyme-linked immunosorbent assay (ELISA);

- Metabolic markers (glucose, total cholesterol, LDL, HDL and triglycerides);

- Insulin sensitivity - OGIS (Oral Glucose Insulin Sensitivity). This measurement is calculated using insulin and glucose values.

Statistical Analysis

Data will be expressed as mean and standard deviation and the variables will be compared by Student's t-test or ANOVA, for repeated measures.