Thigh Muscle Fat May Signal Greater Metabolic and Heart Disease Risk: Study Shows
Spain: A study in The Journal of Clinical Endocrinology & Metabolism suggests that intermuscular fat — though not visible like abdominal visceral fat — is metabolically active and may contribute to chronic inflammation, insulin resistance, and muscle dysfunction, increasing the risk of metabolic and cardiovascular diseases.
The research, led by Alba Camacho-Cardenosa from the Sport and Health University Research Institute (iMUDS), University of Granada, examined how fat stored between muscle fibres in different parts of the body relates to blood sugar control and cardiometabolic health in adults with excess weight.
The multicentre cross-sectional study involved 189 adults (50% women, average age 46.8 years) with overweight or obesity, all with a mean BMI of 32.9 kg/m². Magnetic resonance imaging (MRI) was used to measure intermuscular adipose tissue (IMAT) in the abdominal and mid-thigh regions. Participants wore continuous glucose monitoring (CGM) devices for 14 days to track blood sugar levels throughout the day and night. Researchers also calculated a cardiometabolic risk score based on fasting HDL cholesterol, triglycerides, glucose, waist circumference, and blood pressure.
The following were the key findings of the study:
- Fat stored in the abdominal muscles showed no significant link to glucose control or cardiometabolic risk.
- Higher levels of mid-thigh IMAT were consistently associated with elevated 24-hour, daytime, and nighttime glucose levels.
- Increased mid-thigh IMAT was also linked with higher cardiometabolic risk scores.
- Participants with greater thigh IMAT than abdominal IMAT had significantly higher average blood glucose levels.
- Greater thigh IMAT accumulation was linked to worse overall cardiometabolic profiles.
“These results indicate that the location of intermuscular fat matters — and that hidden fat in the lower body may be a stronger signal of cardiometabolic risk than abdominal IMAT in people with obesity,” the authors noted.
Vicente Javier Clemente-Suárez, PhD, professor of sports sciences at the European University of Madrid, commented on the broader implications, stating that intermuscular fat plays a significant role in cardiovascular disease development. He emphasised the need for both clinicians and the public to look beyond conventional measures such as BMI and waist circumference. According to him, the findings also highlight the potential dangers in “patients with apparent normal weight but hidden metabolic risk.”
The researchers acknowledged some limitations, including the cross-sectional design, which prevents conclusions about causality. All participants were of Caucasian descent, which may limit applicability to other ethnic groups with different fat distribution patterns. Additionally, while two types of CGM devices were used, the team noted that accuracy in this relatively stable, non-diabetic group was consistent with other real-time systems.
"The study highlights the importance of assessing fat deposits in specific body regions when evaluating cardiometabolic risk. Mid-thigh intermuscular fat, in particular, may offer a more sensitive marker of early risk than traditional measures, potentially enabling earlier interventions to prevent metabolic and cardiovascular complications," the authors concluded.
Reference:
Gatti, A., Concepción, M., Manuel, V., J, J., Cabeza, R., Idoate, F., L, J., García Pérez, P. V., Ruiz, J. R., & Labayen, I. Impact of Abdominal and Thigh Intermuscular Adipose Tissue on Glucose and Cardiometabolic Risk in Adults With Obesity. The Journal of Clinical Endocrinology & Metabolism. https://doi.org/10.1210/clinem/dgaf362
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