How does adipose tissue fat content change after a weight loss intervention?

Abstract

Fat-free mass (FFM) estimated by dual-energy X-ray absorptiometry (DXA) and densitometric methods (e.g. underwater weighing or air-displacement plethysmography) contains the fat-free component of adipose tissue. Weight loss reduces triglycerides in adipocytes and this automatically reduces the fat-free component of adipose tissue (assuming the fat fraction percentage is maintained after weight loss). The loss of this fat-free component reflects a reduction in whole body FFM. However, the reduction of the fat-free component of adipose tissue does not mean a change in actual FFM i.e., muscles and organs. Regrettably, little attention has been paid to adipose tissue fat content changes following weight loss. Objective: To discuss the change in fat fraction percentage of adipose tissue following weight loss interventions. Design: Narrative Review. Methods: Databases and a search engine were used to search for relevant articles. Results: There are three possible processes for determining adipose tissue fat content: (i) measure the components of adipose tissue using biopsy samples; (ii) measure the fat mass by DXA and the adipose tissue volume by magnetic reso nance imaging and find the ratio of fat mass to adipose tissue volume; and (iii) measure the chemical shift-based waterfat by magnetic resonance imaging. Conclusion: Very few studies were found that reported changes in adipose tissue fat content with weight loss. We reported changes in adipose tissue fat content using three different processes but a consistent trend was not found. As a result, we were unable to conclude how much adipose tissue fat content changes after weight loss.