It sounds like an unlikely claim, but a large Danish cohort study published in the BMJ (British Medical Journal), which followed nearly 3,000 men and women for over a decade, found that people with the smallest thighs had a substantially higher risk of heart disease and early death — regardless of their overall weight or how much fat they carried around their midsection. Here’s what the research actually found, why it matters, and what to do about it.
Key Takeaways
- A Danish BMJ study found thigh circumference below ~60 cm was linked to significantly higher cardiovascular disease and mortality risk, independent of body fat, smoking, and activity level.
- This isn’t a “bigger is always better” finding — above the 60 cm threshold, there was no extra benefit from larger thighs.
- Thigh size largely reflects muscle mass, which plays a major role in blood sugar regulation and reducing chronic inflammation.
- Functional tests like the sit-to-rise test and bodyweight squats give a rough sense of leg strength without needing a scan.
- Lower-body resistance training two to three times a week can build meaningful strength at any age, including in your 70s and 80s.
What the Study Found
Researchers measured participants’ thigh circumference and followed them for years, tracking cardiovascular disease and mortality. Once thigh circumference dropped below roughly 60 cm (about 23.6 inches), risk climbed steeply — and this held true even after accounting for body fat, smoking, blood pressure, cholesterol, and activity level. That’s what made the finding so notable: the link persisted independent of these other well-known risk factors.
Importantly, this isn’t a case of “bigger is always better.” Above that 60 cm threshold, there was no additional benefit from having larger thighs. The risk was concentrated at the low end — thighs that had significantly wasted away — rather than reflecting a straight-line relationship where more is always better.
Why a Small Thigh Is a Warning Sign
The researchers concluded that thigh circumference was largely capturing muscle mass. A small thigh often reflects too little muscle across the body as a whole. This is one of the few body measurements where a smaller number is the concerning one — nearly every other common measurement, like waist circumference or BMI, works the opposite way, where a larger number signals more risk.
The difference comes down to what’s actually being measured. A large waist mostly reflects visceral fat — the deep, metabolically active fat surrounding organs like the liver and intestines, which releases inflammatory signals linked to heart disease and diabetes. A large thigh, by contrast, is mostly muscle along with subcutaneous fat, a different type of fat that research suggests can be metabolically protective, acting as a safer long-term storage site that keeps fatty acids away from the heart and liver.
Muscle or Fat? How to Tell
A tape measure alone can’t distinguish between a large thigh made mostly of muscle versus one that’s largely soft tissue with little muscle underneath — and a large but weak thigh likely doesn’t carry the same protective benefit. You don’t need a scan to get a rough sense of where you stand. Consider:
- Can you get up from a chair without using your hands?
- Can you get up off the floor without using your hands?
- Can you do 10 bodyweight squats without stumbling or needing support?
- When you tense your thigh muscles, do they feel firm, or soft and flabby?
A strong, muscular thigh is what carries the longevity benefit described in the research — not girth for its own sake.
The Metabolic Role of Leg Muscle
Your legs and glutes make up the largest muscle group in your body, and skeletal muscle is where most of the sugar from your diet gets stored after a meal, under the influence of insulin. When leg muscles are well-developed and active, they help clear blood sugar efficiently and keep insulin levels lower. When they shrink, blood sugar has fewer places to go, contributing over time to insulin resistance and increased risk of type 2 diabetes. This is part of why resistance training has been shown in research to improve insulin sensitivity, often within just a few weeks.
Muscle as a Signaling Organ
Research over the past couple of decades has found that muscle behaves like an active signaling organ. When a muscle contracts, it releases molecules called myokines into the bloodstream, which travel to fat tissue, the liver, blood vessels, and even the brain — helping lower inflammation, support healthy blood vessel function, and even support mood and memory. Because your legs contain such a large share of your total muscle mass, they’re a major source of these protective signals every time you use them.
Why Leg Strength Matters for Independence
Leg strength plays a direct role in fall prevention and recovery — it’s what allows you to catch yourself when you stumble and absorb impact if you do fall. A broken hip later in life is one of the most dangerous events an older body can face, with many people never fully returning to their previous level of independence. Research has found that measures like walking speed and the “sit-to-rise” test (lowering yourself to the floor and standing back up without using your hands) correlate strongly with longevity, similar to grip strength.
How to Build Stronger Legs at Any Age
Thigh muscles respond to training at essentially any age — research has shown people in their 70s, 80s, and beyond can build real strength once they start. The most effective approach is lower-body resistance training two to three times per week, focusing on functional movements like squats, sit-to-stands from a chair, step-ups, and lunges (if your knees allow).
The key principle is progressive overload — gradually asking your muscles to do a little more over time, whether through more repetitions, a deeper squat, or added weight. Pairing this with adequate protein intake (roughly 20–40 grams per meal from sources like eggs, fish, occasional red meat, lentils, or beans) gives your muscles the raw material they need to rebuild.
If you’re older, less confident, or more frail, starting small — even 5 to 10 sit-to-stands from a chair a couple of times a day — is a solid starting point you can build from gradually. None of this requires a gym; bodyweight and a sturdy chair are enough to begin.
A Note on Safety
If you have an existing medical condition or haven’t exercised in a long time, check with your doctor before starting a new exercise routine, since they know your medical history and any medications that might be relevant.
Frequently Asked Questions
Does this mean bigger thighs are always better?
No. The study found no additional benefit above the roughly 60 cm threshold — the risk was specifically concentrated in thighs that were notably smaller, likely reflecting low muscle mass, rather than a straight-line “more is better” relationship.
What if my thighs are large but not very toned?
A tape measure alone can’t distinguish muscle from soft tissue. A large but weak, flabby thigh likely doesn’t carry the same protective benefit as a large, firm, muscular one — functional strength appears to be what matters most.
Is it too late to build leg muscle if I’m older?
No — research has shown people in their 70s, 80s, and beyond can build real strength once they begin resistance training. Starting slowly, such as with a few sit-to-stands from a chair, is a reasonable place to begin.
Do I need a gym to build leg strength?
No. Bodyweight exercises like squats, sit-to-stands, step-ups, and lunges, combined with a sturdy chair for support if needed, are enough to get started and build progressively over time.
Source: Dr. Alex Wibberly
Quick Start Checklist
- ☐ Try the sit-to-rise test and bodyweight squat check to gauge your current leg strength
- ☐ Aim for lower-body resistance training 2–3 times per week
- ☐ Start with squats, sit-to-stands, step-ups, or lunges as your core movements
- ☐ Apply progressive overload — gradually add reps, depth, or light weight over time
- ☐ Get 20–40g of protein at each meal to support muscle repair
- ☐ Check with your doctor first if you have a medical condition or haven’t exercised recently
Disclaimer: This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Consult your doctor before starting a new exercise program, especially if you have an existing medical condition or haven’t been physically active recently.