How do you get intramuscular fat? A guide to its causes and control

October 8, 2025 •

3 min read

Studies show that excessive intramuscular fat (IMF) is linked to various metabolic dysfunctions. Learning how do you get intramuscular fat is crucial for understanding its health implications, as it is influenced by factors like inactivity and poor diet.

Quick Summary

Intramuscular fat accumulates due to factors like inactivity, obesity, aging, and metabolic disorders. Proper nutrition and exercise are key for managing levels and mitigating negative health impacts.

Key Points

IMF vs. Other Fats: Intramuscular fat is stored within muscle tissue, distinct from subcutaneous (under skin) and visceral (around organs) fat.
Cellular Origin: The fat can come from stem cells (FAPs) differentiating into fat cells or from muscle fibers storing circulating fatty acids.
Inactivity is a Major Driver: A sedentary lifestyle significantly increases the risk of unhealthy fat accumulation in muscles.
Athlete's Paradox: Trained endurance athletes can have high levels of intramuscular fat, but it functions as an efficient energy source rather than contributing to metabolic disease.
Health Risks: Unhealthy levels of IMF are associated with insulin resistance, inflammation, and reduced muscle quality, particularly in obese and diabetic individuals.
Prevention and Control: Regular exercise (both aerobic and resistance training) and a healthy diet are the most effective ways to prevent and reduce excessive intramuscular fat.

Intramuscular fat (IMF) is fat stored within skeletal muscle tissue, also known as myosteatosis or fat infiltration. It differs from subcutaneous fat and can be found between muscle fiber bundles (intermuscular fat) and inside muscle cells (intramyocellular lipids or IMCL). While some IMF is normal, excessive amounts, especially with inactivity and poor metabolic health, can be detrimental.

The Cellular Process of Intramuscular Fat

Intramuscular fat develops through complex pathways involving genetics, hormones, and environment. The two primary mechanisms are:

Fibro-adipogenic progenitors (FAPs): These muscle stem cells can differentiate into fat cells under certain conditions, leading to fat deposits between muscle fibers.
Uptake of circulating fatty acids: Muscle cells take up fatty acids from the blood to use as energy or store as IMTG. Excessive storage can occur in obese or insulin-resistant individuals.

Key Factors Contributing to Intramuscular Fat

Several factors influence IMF levels:

Inactivity: A sedentary lifestyle is a major cause of excessive IMF, reducing the muscle's demand for energy and promoting fat storage.
Obesity and Diet: High-calorie, high-fat diets contribute to overall body fat, including intramuscular fat. Fat can be deposited in muscles when other fat stores are full.
Age: Aging often involves sarcopenia (muscle loss), where muscle tissue is replaced by fat and fibrous tissue, increasing IMF.
Genetics: Genetic factors can influence an individual's tendency to store fat in their muscles.
Disease Status: Conditions like type 2 diabetes and insulin resistance are linked to higher IMF, which can worsen insulin resistance.

Contrasting Intramuscular Fat: Healthy vs. Unhealthy

Intramuscular fat in trained athletes differs significantly from the unhealthy accumulation seen in inactive individuals:


Feature	Healthy IMF (Athlete's Paradox)	Unhealthy IMF (Metabolic Dysfunction)
Primary Cause	Regular, high-intensity aerobic exercise.	Sedentary lifestyle, obesity, poor diet.
Fat Location	Primarily as intramyocellular lipid (IMCL) droplets within muscle fibers.	Intermuscular fat between muscle bundles and inside cells.
Metabolic Effect	Improves insulin sensitivity and serves as an efficient energy source.	Decreases insulin sensitivity and promotes inflammation.
Mitochondria	Accompanied by an increased number and size of mitochondria for fat burning.	Mitochondrial dysfunction, reducing fat oxidation.

How to Control and Reduce Unhealthy Intramuscular Fat

To control and reduce unhealthy IMF, focus on diet and exercise:

Regular Exercise: Both resistance training and aerobic exercise are effective. Strength training builds muscle, while aerobic activity uses fat for fuel, reducing IMCL stores. Combine both types of exercise weekly.
Maintain a Healthy Diet: A balanced, calorie-controlled diet is key. Include lean proteins, fiber-rich foods, and limit processed foods.
Weight Management: Reducing overall body fat through diet and exercise helps decrease intramuscular fat.
Stay Active Throughout the Day: Reduce sedentary time with regular movement breaks.

Conclusion

Excessive intramuscular fat is a metabolic concern for most people, not a goal. While normal in small amounts and functional in trained athletes, unhealthy accumulation in inactive or obese individuals poses significant metabolic health risks. An active lifestyle with regular aerobic and resistance exercise, coupled with a balanced diet, is the best approach to prevent and reduce unhealthy IMF and mitigate associated disease risks.

Outbound Link

For those interested in the cellular mechanisms behind fat formation, the National Institutes of Health (NIH) provides in-depth research on fibro-adipogenic progenitors (FAPs) and their role in muscle fat infiltration.

Frequently Asked Questions

Intramuscular fat is fat located within skeletal muscle tissue, specifically between muscle fiber bundles (intermuscular fat) and within the muscle fibers themselves (intramyocellular lipids).

While often used interchangeably, 'marbling' more specifically refers to the visible streaks of intramuscular fat in meat, which is prized for flavor and tenderness. In humans, the health context is different and excessive accumulation can be detrimental.

It depends on the type of exercise and your metabolic health. For trained athletes, endurance exercise can increase intramyocellular lipids as an efficient energy reserve, improving insulin sensitivity. For sedentary individuals, inactivity is more likely to cause unhealthy fat accumulation.

In sedentary or obese individuals, excessive IMF can interfere with the body's ability to use insulin properly. This leads to insulin resistance, a major risk factor for type 2 diabetes and cardiovascular disease.

Yes. Lifestyle changes are highly effective. Regular physical activity, especially combining aerobic and resistance training, along with a healthy diet and weight management, can reduce excessive intramuscular fat.

Unlike subcutaneous fat, excess IMF is not always outwardly visible and can even be present in individuals with a normal BMI. However, it is a key component of sarcopenia, which is a noticeable decline in muscle mass and function with age.

While not a routine test, IMF can be accurately measured using imaging techniques like MRI and CT scans, or more precisely with proton magnetic resonance spectroscopy (1H-MRS) for intramyocellular lipids.