Brown adipose tissue in morbidly obese subjects.

Area of Science:

• Metabolism and Endocrinology
• Obesity Research
• Thermogenesis Studies

Background:

• Brown adipose tissue (BAT) plays a role in adaptive thermogenesis and energy expenditure.
• Obesity is associated with reduced BAT activity, suggesting a potential therapeutic target.
• Previous studies indicated a high prevalence of BAT in adult humans, inversely related to BMI and body fat percentage.

Purpose of the Study:

• To investigate BAT activity in morbidly obese subjects under cold exposure.
• To determine the role of BAT in cold-induced thermogenesis (CIT) in humans.
• To test the hypothesis that morbidly obese individuals exhibit reduced BAT activity upon cold exposure.

Main Methods:

• A personalized cooling protocol was applied to induce maximal non-shivering conditions.
• BAT activity was quantified using positron-emission tomography and computed tomography (PET-CT).
• Data from morbidly obese subjects were combined with previous findings from lean to morbidly obese individuals (n=39).

Main Results:

• Cold-induced BAT activity was observed in only 3 out of 15 morbidly obese subjects.
• A significant correlation was found between BAT activity and body composition (BMI and BF%), explaining substantial variance.
• Obese individuals showed blunted CIT and low BAT activity; BAT-positive subjects exhibited significantly increased energy expenditure upon cold exposure compared to BAT-negative subjects.

Conclusions:

• BAT activity is strongly correlated with body mass index and body fat percentage across a wide range of body compositions.
• Humans with active BAT demonstrate enhanced cold-induced thermogenesis, confirming BAT's role in adaptive thermogenesis.
• Targeting and increasing BAT activity presents a potential therapeutic avenue for treating obesity.