How being overweight can cause Achilles tendonitis – And where you carry your fat matters
- Maryke Louw
- Jul 31
- 5 min read
Carrying extra weight – especially around your waist – might be causing more trouble than just placing extra physical demands on your Achilles tendon. Research links being overweight to changes inside the Achilles tendon itself, increasing your risk of injury. Here's what the science says – and how fat in various areas of your body can cause tendon trouble in different ways.
Remember, if you need help with an Achilles injury, you're welcome to consult one of our team via video call.
The terms tendinitis, tendonitis, tendinosis, and tendinopathy mean the same thing for all practical purposes, and we use these interchangeably in most of our articles.
In this article:
Quick refresher: What is Achilles tendinopathy?
Your Achilles tendon is mostly made up of thousands of collagen fibres packed closely together in parallel. It’s this parallel structure that makes the tendon so strong.
When you have a tendinopathy, part of the tendon becomes injured and the collagen fibres become disorganised, causing the tendon to lose some strength.
Why would extra weight matter? Two paths to tendon trouble
In my opinion, there are two reasons why being overweight might increase your risk of injuring your Achilles: (Note the word "might" – being overweight is just one of many factors that may or may not cause Achilles tendinopathy.)
More load: Every step puts force through the Achilles; more body mass means more force, which might increase the risk of your tendon becoming overworked and injured.
Metabolic effects: Extra fat – especially around the waist – often comes with changes in blood chemistry which can lead to chronic inflammation and can make tendon tissue less healthy and slower to repair.
🤷♂️ But is there evidence to support this? If the extra load was the main problem, "heavy" people due to extra muscle bulk would also be more prone to Achilles injuries, and this is not something we see in practice.
What large-scale studies tell us
A group of researchers analysed a large set of health-records that followed about 16.8 million South Korean adults for up to 8 years.
They used the BMI (Body Mass Index) to classify the study participants as underweight (< 18.5), normal (18.5 to < 23), overweight (23 to < 25), and obese (≥ 25).
They also measured participants’ waist circumference to see whether it mattered in which part of their body they carried fat. The researchers split the participants into three groups based on their waist circumference: the lowest third, the middle third, and the highest third.
Three key findings stand out:
A higher BMI was associated with a higher risk of Achilles tendinopathy and Achilles tendon tears.
Waist size likely matters – A larger waist circumference (a sign of central/abdominal fat) was associated with a higher risk of Achilles tendinopathy but not tears.
People with both a high BMI and a larger waist circumference had the highest risk of tendinopathy and tears.
Another systematic review that pooled studies on various areas of the body found that obesity is linked with a higher risk of tendinopathy and tendon tears (shoulder, elbow, plantar fascia, and more) all over the body and with more complications after tendon surgery.
So, it’s possible that the “extra load” you carry when you’re overweight is not the main reason it can predispose you to Achilles injuries but rather the metabolic changes caused by the fat.
What’s going on inside the tendon?
An increased waist circumference usually means that you have more fat around the organs in your belly area. This type of fat has been shown to eventually lead to insulin resistance and metabolic syndrome, which is typified by unhealthy changes in blood-fat levels (unhealthy cholesterol), prediabetes, and eventually Type 2 diabetes.
Unhealthy blood-fat patterns:
In a matched case-control study, people with chronic mid-portion Achilles tendinopathy had a lipid profile typical of insulin resistance – higher triglycerides, lower HDL, and a higher TG/HDL-C ratio – even when their age, sex, and BMI were similar to people without the tendinopathy.
Lab studies on human cells have shown that LDL cholesterol (the bad type) can dial down collagen production – remember that collagen is the main building block of tendons.
Unhealthy blood-fat levels have also been shown to negatively impact tendon health in rabbits and mice.
Diabetes and collagen “messiness”: Studies have shown that diabetes can thicken tendons and disrupt how collagen fibres are organised.
Hormones from fat tissue: Experimental work (on cells and on animals) shows that leptin – a hormone that often rises with more body fat (especially fat under the skin, not just in the belly) – can push tendon cells toward early “aging” and worse healing.
👉 Bottom line
Extra fat weight can raise tendon injury risk through a combination of more load and metabolic changes that make tendon tissue less robust.
Improving metabolic health through losing those extra pounds alongside a good exercise-based strengthening program is a practical, research-informed plan for both preventing Achilles injuries and better recovery from them.
How we can help
Need help with your Achilles injury? You’re welcome to consult one of the team at TMA online via video call for an assessment of your injury and a tailored treatment plan.
We're all UK Chartered Physiotherapists with Master’s Degrees related to Sports & Exercise Medicine or at least 10 years' experience in the field. All of us have a wealth of experience working with athletes across a broad variety of sports and ranging from recreationally active people to professional athletes. You can meet the team here.
About the Author
Maryke Louw is a chartered physiotherapist with more than 20 years' experience and a Master’s Degree in Sports Injury Management. Follow her on LinkedIn and ResearchGate.
