Asking if fat or muscle is more important when it comes to heart health is not as profound as asking which came first between the chicken and the egg, but it has greater implications for your body. Researchers from the University of Bristol in England have determined early markers of heart health are impacted more by losing fat than gaining muscle.
More than 3,200 study participants were tracked between the ages of 10 and 25 and had their body fat and lean muscle mass measured many times during that span. The results of the observational study were published in a recent issue of the journal PLOS Medicine.
When participants reached the age of 25 they had their blood measured for more than 200 markers of metabolism through a technique called metabolomics. Researchers were interested in things such as harmful cholesterol, glucose and inflammation since the combination is a good indication of a person’s susceptibility of developing heart disease and other health conditions.
"We knew that fat gain is harmful for health, but we didn't know whether gaining muscle could really improve health and help prevent heart disease," Dr. Joshua Bell said. "We wanted to put those benefits in context."
The study showed gaining fat mass was strongly and consistently related to poorer metabolic health in young adulthood. The detrimental effect of fat accumulation was as much as five times greater than any benefit of gaining muscle. The benefits of gaining muscle appeared to be limited to increases which happened during adolescence. That observation led researchers to conclude this time period may be an important window for muscle development and its associated benefits.
"Fat loss is difficult, but that does seem to be where the greatest health benefits lie," Dr. Bell said. "We need to double down on preventing fat gain and supporting people in losing fat and keeping it off. We absolutely still encourage exercise—there are many other health benefits and strength is a prize in itself. We may just need to temper expectations for what gaining muscle can really do for avoiding heart disease—fat gain is the real driver."
The study also found improving strength translated to slightly higher benefits than gaining muscle itself. That suggested to researchers the frequent use of muscle was more important than just adding bulk.
"This research provides greater clarity in the relative roles of fat and lean mass in the basis of cardio-metabolic disease," Researcher Nic Timpson said. "This is an important finding and clearly part of a complex picture of health that involves weight gain, but also the other indirect costs and benefits of different types of lifestyle."