Adaptation of human brown adipose tissue to overnutrition

ended

Brown adipose tissue (BAT) is a highly thermogenic tissue whose main function is to produce heat to maintain mammals’ body temperature. In humans, it has long been believed that BAT is either absent or irrelevant in adults. However, a decade ago, several independent research groups confirmed the presence of metabolically active BAT in human adults. In rodents, BAT plays a key role in the adaptation to overfeeding, protecting murine from diet-induced obesity. Whether this phenomenon also occurs in humans is still unknown. To date, technical limitations for in vivo human BAT assessment have precluded us from adequately studying it. The BATON study will first aim to develop a new method to accurately measure human BAT volume and thermogenic capacity in vivo. New approaches based on recent advances in human BAT metabolism (i.e. BAT’s unique ability to burn its own intracellular triglycerides and the recently discovered, and unexpected, capacity of human BAT to be activated through β2 adrenergic receptor agonism) will be tested in a randomized cross-over study. Ten young healthy adults (18-30 years old, 5 men and 5 women, with a body mass index <25kg/m2) will undergo 3 experimental sessions including sequential positron emission tomography-computerized tomography and magnetic resonance imaging and spectroscopy scans. Later, the newly develop method(s) will be used to measure BAT volume and thermogenic capacity changes in response to a 4-week 40% overfeeding, in a proof-of-concept overfeeding pilot study. Twelve healthy adults (18-30 years old, 6 men and 6 women) with a body mass index <25kg/m2 will participate in this randomized controlled trial. After baseline assessments, participants will be randomized (blocking the randomization by sex) to a 4-week weight maintenance diet (control group) or a 40% overfeeding diet. A 5-days weight maintenance diet will be prescribed before baseline and post-intervention assessment.