Researchers from the Exercise, Health, Metabolism and Functional Capacity (EFIT) Group at the Public University of Navarra (UPNA) and Navarrabiomed have found that good cardiorespiratory fitness (commonly referred to as aerobic fitness or endurance) is associated with a lower prevalence of depressive symptoms in female university students, regardless of their body fat levels. The study, published in the Elsevier journal Mental Health and Physical Activity, analyzed data from 251 female university students with a mean age of 20.6 years. The results showed that nearly one in three participants presented clinically relevant depressive symptoms. Furthermore, the study found that the combination of low physical fitness and high body fat percentage doubled the likelihood of experiencing such symptoms.

The research was conducted by Mikel Gutiérrez García, Sergio Oscoz Ochandorena, Mikel Izquierdo Redín, and Robinson Ramírez Vélez, the latter two serving as senior authors. To carry out the study, the team employed gold-standard methods for assessing body composition and physical fitness. Body fat was measured using dual-energy X-ray absorptiometry (DXA), while cardiorespiratory fitness was assessed through a cardiopulmonary exercise test on a cycle ergometer (a medically adapted stationary bicycle), which directly measures maximal oxygen uptake (VO₂max). Depressive symptoms were evaluated using the CES-D-10 scale, an internationally validated screening tool.

Thirty Percent Showed Relevant Depressive Symptoms

The findings confirm the considerable mental health burden within this population. Thirty percent of the students assessed exceeded the clinical threshold for depressive symptoms. In addition, 61% had a high body fat percentage, defined as 32% or higher, despite having a body mass index (BMI) within the range generally considered normal.

According to the research team, this result highlights “the limitations of body mass index (BMI) as a sole indicator of health in young women.” BMI relates weight to height but does not distinguish between fat mass, muscle mass, and other body components, which means it may fail to detect excessive adiposity in individuals whose body weight appears normal.

Participants were classified into four groups according to their body fat percentage and aerobic fitness levels. This classification followed the internationally recognized “fat-but-fit” model, a term used to describe individuals who have excess body fat but maintain good physical fitness.

The analysis revealed a clear pattern. Students with high adiposity and low fitness levels recorded the highest depressive symptom scores and were twice as likely to present clinically relevant depressive symptoms compared with the reference group, which consisted of participants with low adiposity and good physical fitness.

By contrast, students with high adiposity but good cardiorespiratory fitness did not show significant differences compared with the reference group. According to the researchers, this finding suggests that “good physical fitness may buffer the potential negative psychological effects associated with excess body fat.”

“The main finding is that what defines the highest-risk group is neither body fat alone nor low fitness in isolation, but the combination of both,” explains Mikel Izquierdo. “This changes the preventive approach: improving physical fitness can be a very powerful protective tool for mental health, even when body weight does not change.”

Implications for University Public Health

According to the authors, the study offers two methodological advantages over previous research. First, it uses objective and direct measurements, such as DXA scans and cardiopulmonary exercise testing with gas analysis, rather than estimates based solely on BMI or physical activity questionnaires. Second, it focuses on a relatively understudied population facing an increasing burden of mental health challenges: young women attending university.

“The transition to university coincides with a critical period from hormonal, social, and academic perspectives, increasing vulnerability to mood disorders, particularly among women,” says Robinson Ramírez, the study’s principal investigator. “Our data suggest that promoting improvements in aerobic fitness within this population could represent an accessible, low-cost, and non-pharmacological strategy to support mental health.”

Among the possible biological mechanisms underlying this association, the researchers note that physical exercise may help reduce systemic inflammation, stimulate factors linked to brain health, and improve regulation of the autonomic nervous system, which plays a key role in the body's response to stress. On a personal and social level, exercise may also help students feel more capable, strengthen confidence in their own abilities, and improve their relationship with their body image.

The study’s authors believe that universities can play an important role in mental health prevention and support by implementing structured physical fitness promotion programs. According to the research, such initiatives could be integrated into university well-being policies as an accessible, evidence-based strategy for enhancing student mental health