Abstract
OBJECTIVE: Cholecystectomy (GBX) may alter energy metabolism, but human evidence is limited. We examined whether GBX alters energy expenditure (EE), respiratory exchange ratio (RER), and substrate oxidation. METHODS: A total of 384 healthy Southwestern Indigenous American adults (222 males, age 28 ± 6 years) were studied, including individuals with a history of gallbladder surgery [GBX(+), n = 39] and without surgery [GBX(-), n = 345]. In addition, 24-h energy metabolism was measured in a respiratory chamber. General linear models were adjusted for age, sex, body composition, and glucose regulation. RER and macronutrient oxidation rates were further adjusted for energy balance. RESULTS: GBX(+) participants were older (31 ± 7 vs. 27 ± 6 years, p = 0.0002) and mostly female (95% vs. 36%, p < 0.0001), and they had higher body fat (40% ± 5% vs. 32% ± 8%, p < 0.0001), although body composition differences were sex related. Adjusted models showed lower RER (β = -0.01, p = 0.01), higher lipid oxidation (β = 79 kcal/day, p = 0.03), and higher sleep EE (β = 78 kcal/day, p = 0.006) in the GBX(+) group. Other EE variables and macronutrient oxidation rates were not significantly associated with GBX history (all p's > 0.1). CONCLUSIONS: Independent of obesity, an absent gallbladder is associated with decreased RER and increased lipid oxidation and sleep EE rates, indicating that the gallbladder may have a role in metabolic fuel selection that has implications for metabolic health. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT00339482, NCT00340132.