There are many benefits to exercise, including fat loss, but exercise does not burn fat the same way for everyone. A study by researchers in the NIH Common Fund-supported Molecular Transducers of Physical Activity Consortium (MoTrPAC) have uncovered striking differences in how male and female fat tissue adapts to exercise in rats, providing further support that a one-size-fits-all approach isn’t best when it comes to fitness and metabolism.  

MoTrPAC researchers tasked male and female rats to run on a treadmill five days a week for up to eight weeks. They found that female rats lost fat after four weeks but regained it by week eight, while males kept losing fat throughout the study.  

The researchers analyzed 18 different tissues and blood samples from rats to understand these differences on a molecular level. They found that at four weeks, both male and female rats had smaller, more uniform fat cells, consistent with fat loss. By eight weeks, female fat cells had returned to their original size, resembling those of the sedentary rats. This suggests that female rats may have a built-in metabolic response that compensates for fat loss, a phenomenon not seen in males. 

This study is just the beginning of what MoTrPAC aims to uncover about exercise and its potential benefits throughout the body. By mapping how exercise affects tissues and organs at a molecular level, researchers hope to better understand how physical activity improves health. Understanding these differences could lead to more personalized fitness and health recommendations, helping everyone get the most out of exercise. 

The study was led by MoTrPAC researchers Sue Bodine, Ph.D., of the Oklahoma Medical Research Foundation, Simon Schenk, Ph.D., of the University of California San Diego, Christopher Newgard, Ph.D., of the Duke Molecular Physiology Institute, and Joshua Adkins, Ph.D., of the Department of Energy’s Pacific Northwest National Laboratory. 

For more information on MoTrPAC, visit the NIH Common Fund website or the Consortium’s website. 

Reference: Many, G.M., Sanford, J.A., Sagendorf, T.J. et al. 2024. Sexual dimorphism and the multi-omic response to exercise training in rat subcutaneous white adipose tissue. Nat Metab 6, 963–979. doi: 10.1038/s42255-023-00959-9