The study found that vigorous exercise burns more fat in males than females, which was an unexpected discovery. The largest study to date on the effects of exercise on the body revealed this surprising result. Joshua Adkins, a scientist at the Department of Energy’s Pacific Northwest National Laboratory and a corresponding author of the study published online on May 1 in Nature Metabolism, stated, “Everyone knows that exercise is good for you, but no one knows exactly why. We don’t know what’s happening in the body that causes these differences.”The benefits of exercise are significant, according to the results of a study conducted by the Molecular Transducers of Physical Activity Consortium (MoTrPAC). This collaborative research effort involved over 100 scientists from more than two dozen sites across the country and focused on understanding the molecular mechanisms behind the health benefits of physical activity.
Published in the journal Nature on May 1, the study found that exercise has a widespread impact, affecting over 35,000 molecules in the body. No tissue studied was unaffected by the effects of exercise. The research was conducted on rats, which have similar basic physiology to humans.a group of researchers is currently examining over 1,500 individuals, using the results from experiments on rats as a starting point for exploring the effects of exercise on humans. The MoTrPAC team analyzed 18 different types of tissue as well as blood, and discovered molecular signals in both men and women that showed significant benefits of physical activity. These included improved liver function, stronger heart muscles, enhanced immune system, and reduced inflammation in the lungs and intestines. In addition, exercise was found to promote healthier mitochondria, which are responsible for producing energy in cells. The Nature Metabolism paper focused on the differences in fat tissue between males and females, even in sedentary animals. Christopher Newgard, the corresponding author and director of the Duke Molecular Physiology Institute, was surprised by the significant disparities in the sex-dependent responses to exercise. While males burn fat for energy, females preserve their fat mass. This is due to numerous molecular response differences in fat from male compared to female rats, which Newgard found to be truly striking.
In addition to Adkins and Newgard, the main authors of the Nature Metabolism paper are Sue Bodine from the Oklahoma Medical Research Foundation and Simon Schenk from the University of California San Diego. The paper has three “first authors” from PNNL: Gina Many, James Sanford, and Tyler Sagendorf.
Results from active rats
The findings are based on an examination of tissues and blood samples from rats that were running on treadmills in a research laboratory at the University of Iowa. The team conducted numerous measurements of proteins, molecular messengers known as transcripts, and chemical compounds called metabolites.
Researchers use measurements of metabolites to gain insights into the inner workings of the body. Every breath, thought, movement, or treadmill workout sets off a series of molecular processes that influence the body’s functions. The samples were sent to multiple labs for examination. At PNNL, the scientists focused on analyzing the proteins in the fat samples, which was a challenging task due to the low protein content in fat compared to lipids. Their study focused on white adipose tissue, which is the most common type of fat in the body. The researchers observed the effects of running on rats that exercised five days a week for varying durations, comparing them to sedentary rats.The researchers focused on healthy, lean rats, emphasizing that the results of the study may not be directly applicable to obese animals or other forms of exercise, such as strength training.
Reduced fat, same fat levels, healthier fat
The difference in fat composition was significant even among sedentary male and female rats, with over 20,000 molecular differences. Overall, the fat in female rats was found to be healthier both before and after the exercise regimen.
All rats gained weight during the study, with those that ran on the treadmill showing even more significant differences. Male rats burned fat and kept it off, while female rats initially burned fat but eventually returned to their original fat stores. Male rats that exercised lost fat, while female rats did not lose fat but also did not gain as much fat as those who were sedentary.
Exercise made the fat stores of both male and female rats healthier, with fewer signals associated with obesity. This effect was more pronounced in male rats, whose fat became less.healthy to begin with.
“We observed both genders activating their metabolism to obtain the necessary energy,” stated lead author Gina Many. “However, they acquire their energy through different methods. Females are able to do so without depleting much of their fat reserves, most likely because these are crucial for reproductive health.”
In recent years, researchers have discovered that fat is not just an unwanted mass. It is a vital organ that exists throughout our body, similar to the skin, and releases hormones and other substances that play a significant role in our overall health. Fat serves as both a source of wellness and illness.
A comparison from rats to humans
“ThThe findings provide valuable insight into understanding disease risk and lay the foundation for more personalized health interventions,” stated Many.
The researchers emphasized the importance of including both women and men in health studies, pointing out that there has been a significant imbalance in the research conducted on exercise, with more focus on men than women.
Newgard expressed surprise at the significant differences between the sexes revealed in this study. He acknowledged that it has prompted a shift in his approach to other studies, including one on insulin resistance in both males and females. These findings will guide future experiments in this area.The MoTrPAC study is financially supported by the National Institutes of Health Common Fund. Many of the protein analyses discussed in the Nature Metabolism paper were conducted at the Environmental Molecular Sciences Laboratory, which is a DOE Office of Science user facility located on the PNNL campus. The technologies used by the PNNL team in the MoTrPAC experiment are also utilized to investigate molecular reactions that are significant for climate, energy, and the environment.
