August 3, 2025, 3:20 pm | Read time: 5 minutes
Many people who want to lose weight put on their running shoes out of conviction. Running is considered an effective way to lose weight because it burns a lot of calories. However, Finnish researchers can only partially confirm this: Based on study results, they see the benefits of running elsewhere.
Running engages a relatively large number of muscles. It’s not just the legs that move; the entire musculoskeletal system must remain stable, which is why, for example, the abdominal and back muscles are also active. This makes it quite strenuous, and the calorie consumption is relatively high. Nevertheless, researchers warn that running does not directly help with weight loss.
Researchers at the University of Jyväskylä have examined the long-term effects of running sports. Specifically, they investigated whether and how regular running training affects age-related physical changes. Their study was published in 2023 in the journal “Frontiers.”1
It is known that from around the age of 30, so-called sarcopenia progressively sets in. This term refers to the natural age-related loss of muscle mass, which is also accompanied by a loss of muscle strength. Therefore, as people age, it becomes more challenging to build or maintain muscle and lose weight.
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Why Running Only Leads to Short-Term Weight Loss
The topic of losing weight through running has been hotly debated in recent times. This is according to the press release from the Finnish university’s study.2 Some researchers even speak of a myth when it comes to running helping with weight loss. There is evidence that the human body, after starting a new running routine, eventually takes energy-saving measures. Initially, one may lose weight quickly, but then the body’s overall consumption regulates downward–according to the press release, a kind of “insurance policy of nature (…) to avoid starvation during times of limited food availability.” In the long term, running is said to have even more favorable effects.
Details of the Study
For their analysis, the team led by study director Dr. Simon Walker used data from the Athletes Aging Study (ATHLAS-Study). This includes information from male participants in the age groups 20 to 39 (109 participants) and 70 to 89 years (147 participants), including their body compositions (such as bone density, muscle, and fat mass, etc.). Some of the men were competitive athletes, including sprinters, endurance runners, and strength athletes. A control group consisted of 147 participants who were generally physically active and occasionally engaged in sports, but not to a competitive extent.
Finding: Running Leads to Less Body Fat in the Long Term
“Our data clearly show that lifelong running, whether over long distances or repeated short sprints, leads to a lower fat percentage than a typical physically active lifestyle,” explains lead author Walker. It also had a stronger impact than any involvement in strength sports. Even older sprinters and endurance athletes had a lower body fat percentage than younger participants in the strength athlete or control group.
In simple terms, running may not directly help with weight loss, but it does help prevent weight gain. It can apparently contribute significantly to keeping body fat percentage low in the long term.
Positive Impact on Muscle Mass as Well
For a healthy body, the proportion of muscle mass is also important. It would be expected to be higher among the strength athletes in the study–this was anticipated and was also assumed by study director Walker and his team. Indeed, this was the case, although the data from the endurance athletes were surprising. They had muscle mass above the sarcopenia threshold defined for their respective age, even in advanced life stages. The results suggest that regular running might be sufficient to remain fit into old age.
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Further Studies Confirm Effects
Running Reduces Belly Fat–Even with Moderate Training
In another study from 2023, adults aged 18 to 65 were examined. Those who regularly ran at least ten kilometers per week had significantly less body fat on average than those with little exercise–especially in the abdominal area. Weight and body mass index (BMI) were also lower among the runners. The scientists conclude that even regular, moderate running can help lose excess fat–particularly in areas that are especially relevant to health.3
Those Who Run for Years Have Significantly Less Body Fat
A 2020 study examined middle-aged men who had been running long distances regularly for many years–about 80 kilometers per week. Compared to non-runners of the same age, they had about 8.5 kilograms less body fat on average. The difference was particularly pronounced in the so-called “visceral fat,” which is considered a risk factor for many diseases. The runners also had significantly less fat on their arms, legs, and torso. The study shows that those who stick with it for years can keep their body fat percentage low in the long term.4
What the Study Authors Recommend
The results show the enormous health benefits of running–if not for weight loss, then for weight regulation and even for maintaining muscle mass. However, “to maintain optimal body composition in old age,” the responsible researchers recommend a combination of running or sports and other health-promoting routines. A balanced diet is also suggested.
The recommendations also apply to women. Even though only male participants were involved in the study, “I see no reason why our results should not also apply to women,” explains study director Walker, “especially when considering the effects of menopause and other age-related factors.”