(P16-032-23) Intestinal Energy Harvest Significantly Increased Post-Surgery: The Role of Energy Absorption Pre and Post Bariatric Surgery

Objectives: Class III obesity is a complex chronic disease characterized by a body mass index ≥40 and is associated with health conditions such as inflammation and insulin resistance. To date, metabolic and bariatric surgery (MBS), is the most effective treatment to induce body weight loss and metabolic improvement in patients with Class III obesity. However, a significant subset of post-surgery patients do not achieve expected weight loss or experience significant weight recurrence. The factors contributing to the variations in weight loss outcomes remain unclear. Previous studies suggest a role of the gut microbiota in shaping interindividual variations in energy balance, which is related to energy harvest, energy expenditure, and weight changes. This study aims to investigate the enteric energy harvest and its influence on weight loss outcomes following bariatric surgery.

Methods: Fecal samples were collected from sixty-six patients at two clinical locations pre- and post-MBS (Roux-en-Y Gastric Bypass and Sleeve Gastrectomy)—1, 6, 12, 18, and 24 months. Fecal energy density was measured at baseline and 12 months via bomb calorimetry (Parr 6200 Calorimeter). Stool calorie loss (a proxy for lack of calorie harvest) was calculated as (1) calories per g of sample and (2) relative energy content (number of calories in a stool sample divided by the number of calories consumed the previous day).

Results: Paired t-tests revealed that MBS patients had significantly increased relative energy content (less energy absorbed from the gut) post-surgery (p < 0.01). A Mann-Kendall Trend Test indicated a significant correlation between energy harvest rate and weight loss rate between baseline pre-surgery and 12 months post-surgery, i.e. lower relative energy content at baseline is significantly associated with higher weight at 1, 6, 12 months post-surgery (p < 0.01).

Conclusions: Gut energy harvest plays an important role in contributing to weight loss outcomes among bariatric surgery patients. Findings from this study will benefit the early detection of patients with a higher risk of suboptimal weight loss outcomes and lead to timely interventions, whether it’s pharmaceutical, nutritional, or lifestyle.

Funding Sources: National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health