Reduced brown adipose tissue activity during cold exposure is a metabolic feature of the human thrifty phenotype.

Abstract

BACKGROUND\nWe recently demonstrated that thrifty subjects, characterized by a greater decrease in 24\u202fh energy expenditure (24hEE) during short-term fasting, have less capacity for cold-induced thermogenesis (CIT) during 24\u202fh of mild cold exposure.\n\n\nOBJECTIVE\nAs cold-induced brown adipose tissue activation (CIBA) is a determinant of CIT, we sought to investigate whether thrifty individuals also have reduced CIBA.\n\n\nMETHODS\nTwenty-four healthy subjects (age: 29.8\u202f±\u202f9.5y, body fat: 27.3\u202f±\u202f12.4%, 63% male) were admitted to our clinical research unit and underwent two 24hEE assessments in a whole-room indirect calorimeter during energy balance and fasting conditions at thermoneutrality to quantify their degree of thriftiness. Positron emission tomography/computed tomography scans were performed after exposure to 16\u202f°C for 2\u202fh to quantify peak CIBA.\n\n\nRESULTS\nA greater decrease in 24hEE during fasting was associated with lower peak CIBA (r\u202f=\u202f0.50, p\u202f=\u202f0.01), such that a 100\u202fkcal/day greater reduction in 24hEE related to an average 3.2\u202fg/mL lower peak CIBA.\n\n\nCONCLUSION\nOur results indicate that reduced CIBA is a metabolic trait of the thrifty phenotype which might explain reduced CIT capacity and greater predisposition towards weight gain in individuals with a thrifty metabolism.