Abstract:
Background
Obesity and its comorbidities have been increasing at an alarming rate and have thus become a major public health concern worldwide. Recently, brown adipose tissue activation (BAT) and white adipose tissue (WAT) browning have emerged as potential targets for combating obesity and metabolic disorders, largely triggered by the revolutionary discovery of the presence of active BAT in adult humans and its capacity to counteract obesity and metabolic disturbances in animals.
However, human data on the impact of BAT activation/WAT browning on humans remains scarce, especially that there is a considerable discrepancy in thermogenesis mechanism between mice and humans. Similarly, studies have also shown that food restriction/exercise in mice can activate BAT and induce beige fat. However, it remains unclear in humans as to whether these known interventions such as lifestyle modification program (LMP) in the treatment of obesity can activate BAT/induce WAT browning.
Mostly because LMP studies have only been focused on the treatment of obesity and have scarcely been focused on activation of BAT/induction of WAT browning in humans. Thus, the aim of this pilot study was to assess the activation of BAT, browning of white fat, and to detect reversal of metabolic syndrome, non-alcoholic fatty liver disease (NAFLD), non-alcoholic fatty pancreas disease (NAFPD), and altered insulin resistance over 6-month period.
Methods
9 morbidly obese and 9 health lean control subjects were recruited in this pilot study. LMP was employed to induce weight loss and consequent activation of BAT and induction of WAT browning in morbidly obese subjects. MRI was used to measure BAT/WAT in the neck region (BAT depots) at baseline and 6 months by measuring their T2* and fat fraction using a validated in-house algorithm. Blood biochemistry and anthropometrics were also measured.
Results
A median %weight loss of -1.15%, p=0.593 was achieved. This %weight loss resulted in:
• Significant % decrease in pancreatic and liver fat fractions (-15.04%, p=0.021 and -31.77%, p=0.015, respectively).
• % decrease in BAT fat fraction of -3.22%, p=0.953 and BAT T2* of -4.47%, p=0.953.
• % decrease in WAT fat fraction of -25.74%, p=0.008 and WAT T2* of -57.63%, p=0.021. Indicating the possible occurrence of WAT browning.
• No difference between the intervention group-WAT fat fraction vs. control- BAT fat fraction (66.65% vs. 60.18%, p=0.853) and no difference between the intervention group-WAT T2* vs. control- BAT T2* (28.94ms vs. 17.22ms, p=0.060). Suggesting the occurrence of WAT browning vis-à-vis increased metabolic activity in WAT of the morbidly obese subjects to the levels of BAT metabolic activity in the lean control subjects.
•No statistically significant differences in the BAT fat fraction and BAT T2* between the intervention group and control group (66.22% vs. 60.18%, p=0.310 and 30.19ms vs. 19.43ms, p=0.171, respectively). Implying that the BAT metabolic activity in the intervention group was similar to that of the control group.
•BAT/WAT T2* at 6 months of LMP group showed a trend of inverse correlation with obesity, metabolic disorder components, certain pro-inflammatory cytokines and adipokines.
Conclusion
LMP may be an effective method in inducing WAT browning but seems to have minimal effect on BAT activation, nonetheless, this outcome requires confirmation using large sample sizes. BAT and WAT browning could be a potential treatment of obesity and its comorbidities.
What will the audience learn from your presentation?
- It could contribute to the academic field to understand the mechanism of activation of brown fat and induction of browning in white adipose tissue as a potential treatment for obesity and related comorbidities.
- It could indirectly promote healthful eating and living habits among the population with or without obesity resulting in a healthier population.
- It could help enhance more personalized treatment especially that clinicians often have difficulties in managing obesity as this is purely dependent on an individual’s chosen lifestyle with limited intervention from the clinicians. Further, this could aid a reduction in waiting time/costs of those earmarked for bariatric surgery and a reduction in the workload of the clinicians/medical personnel responsible for managing such patients.
