You've probably heard it since you were a kid. Maybe your grandma said it to explain why you were a bit sturdier than the other kids on the playground, or maybe you've used it yourself when looking at a scale that just won't budge. "I'm not overweight, I'm just big boned." It sounds like a polite euphemism. A way to soften the blow of a high BMI. But here’s the thing: it’s actually a real physiological reality, though probably not in the way you think.
Bone structure is incredibly diverse. Some people really do have a skeleton that carries more mass, occupies more volume, and provides a wider "shelf" for muscle and fat to sit on. But don't get it twisted. Being big boned isn't a medical diagnosis for obesity, nor is it a myth invented by people who hate salads. It’s about frame size.
What Does It Actually Mean to Be Big Boned?
When we talk about being big boned, we’re technically talking about bone density and the circumference of the skeleton. It’s the literal architecture of your body. Think about the difference between a bird and a buffalo. Both have skeletons, but the buffalo’s framework is built for heavy lifting and massive force. Humans have a similar, albeit less extreme, variation.
The medical community generally uses the term frame size to categorize people into small, medium, or large categories. This isn't just about height. You can be five-foot-two and have a large frame, or six-foot-four and have a surprisingly delicate skeletal structure. It’s about the breadth of your shoulders, the width of your hips, and the thickness of your wrists and ankles.
The Wrist Test and Elbow Breadth
How do doctors actually measure this? They don’t usually stick you in a DEXA scan just to see if you're "sturdy." Instead, they use proxies. One of the most common is the elbow breadth measurement. A health professional will have you extend your arm and measure the distance between the two bony protrusions on either side of your elbow (the epicondyles). Because there’s very little fat or muscle over those specific spots, it gives a remarkably accurate picture of your skeletal width.
Another classic is the wrist circumference. Take your thumb and middle finger and wrap them around your opposite wrist. If they overlap, you’re likely small-framed. If they just touch, you’re medium. If there’s a gap? That’s what people mean by being big boned. While it’s not a perfect laboratory science, it’s a solid indicator of your body's "chassis."
The Weight of Your Skeleton
Here’s where the "big boned" excuse usually falls apart in a doctor's office. How much does a skeleton actually weigh? Honestly, not as much as you'd think.
In an average adult, the entire skeleton—dry and stripped of everything else—only accounts for about 15% of total body weight. For a 200-pound person, that’s 30 pounds of bone. If that person has a "large frame" compared to a "small frame," the difference in bone weight is usually only about two to five pounds.
Basically, your bones aren't making you "heavy" in the way a 50-pound weight gain does.
However, that’s not the whole story. A larger frame allows for—and often requires—more muscle mass and more connective tissue. If you have wide shoulders and a thick ribcage, you have more surface area for muscle attachment. You naturally carry more "lean mass" just to move that bigger frame around. This is why two people can be the same height and weight, but one looks lean and the other looks soft. The person who is truly big boned has a higher "weight floor" because of the sheer volume of their structural components.
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Why BMI Fails Large-Framed People
The Body Mass Index (BMI) is a blunt instrument. It was developed by a Belgian mathematician named Adolphe Quetelet in the 19th century, and he specifically said it shouldn't be used to judge individual health. Yet, here we are.
BMI only cares about height and weight. It doesn’t know if your weight is coming from a dense, wide skeleton and heavy musculature or from adipose tissue. This is why "big boned" individuals often find themselves in the "overweight" or even "obese" category of the BMI chart while being perfectly healthy and relatively lean.
A Real-World Example: The Athlete Paradox
Look at a professional rugby player or a heavyweight wrestler. By BMI standards, they are morbidly obese. But if you looked at their bone density scans, you'd find bones that are thick, mineral-dense, and wide. Their "big boned" nature is what allows them to withstand the physical impact of their sport. For these people, trying to hit a "normal" BMI would be physically impossible without losing massive amounts of essential muscle and potentially weakening their bone structure.
The Genetics of Bone Structure
You can’t outrun your ancestors. Research into the LRP5 and SOST genes shows that bone density and skeletal size are highly heritable. Some populations, particularly those from colder climates or those who evolved for high-intensity physical labor, tend to have wider bi-iliac (hip) widths and thicker cortical bone.
It’s about evolution. A wider frame can be an advantage in certain environments for heat retention or power. If your parents both have thick wrists and wide shoulders, the odds are you will too. You didn't choose your frame; you inherited the blueprint.
The Mental Trap: Is it an Excuse?
We have to be honest here. While being big boned is a real thing, it has also become a shield.
In the 1970s and 80s, the phrase became a way to talk around weight issues without causing offense. This led to a backlash where many health "gurus" claimed the concept was a complete myth. Both sides are wrong. The skeleton exists, and it varies in size. But the skeleton doesn't store fat—fat stores fat.
If you have a large frame, you might naturally weigh 10 to 15 pounds more than someone with a small frame at your same height. But if you are 60 pounds over your "ideal" weight, the bones are only a small part of that equation. Understanding the difference is the key to actual health. It's about accepting your shape while managing your composition.
Bone Density vs. Bone Size
It’s easy to confuse these two.
- Bone Size: The physical dimensions (length and width).
- Bone Density: How much mineral (like calcium and phosphorus) is packed into that space.
You can have a large frame with low bone density (osteoporosis), which is a dangerous combination because you have a lot of leverage on fragile structures. Conversely, someone can be small-framed but have incredibly "heavy" or dense bones. Most people who call themselves big boned are referring to size, but density is actually what matters for long-term health.
How to Work With the Body You Have
If you've realized you are legitimately large-framed, your approach to fitness and health should reflect that. You aren't built to be a marathon runner with a "willowy" physique. You might be built for powerlifting, sprinting, or swimming.
Don't Chase a Number
Stop looking at the standard weight charts at the doctor’s office if they don’t account for frame size. Instead, focus on body fat percentage and waist-to-hip ratio. These are much better indicators of health for someone with a heavy skeleton. If your waist is trim but the scale says you're heavy, your "big bones" and the muscle they support are likely the reason.
Support the Load
A larger frame puts more stress on joints. If you are big boned, you need to be meticulous about joint health. This means:
- Focusing on low-impact steady-state cardio (LISS) to protect the knees.
- Prioritizing strength training to ensure your muscles are doing the work of moving your frame, not just your ligaments.
- Ensuring adequate Vitamin D and K2 intake to maintain the density of that larger skeleton.
Moving Beyond the Euphemism
Honestly, it’s time we stopped using "big boned" as a joke or a deflection. It’s a biological trait that dictates how we move, how we look, and how we should exercise. Recognizing that you have a large frame is an act of body literacy. It allows you to set realistic goals. You wouldn't try to turn a Ford F-150 into a Mini Cooper; you'd focus on making sure that F-150 is the highest-performing truck it can be.
Practical Next Steps for Assessing Your Frame
- Measure your wrist: Use a soft measuring tape right above the wrist bone. For a man over 5'5", a wrist over 7.5 inches is generally a large frame. For a woman, over 6.75 inches is large.
- Check your elbow breadth: Stand in front of a mirror, bend your arm to 90 degrees, and use a caliper or even a ruler to see the width of the bone. Compare this to standard NHANES (National Health and Nutrition Examination Survey) charts.
- Get a DEXA scan: If you really want to know what's going on under the hood, this is the gold standard. It will tell you exactly how many pounds of your body are bone, fat, and lean mass.
- Shift your metrics: If you are in the large frame category, add 10% to your "ideal" weight range on standard charts. This gives a much more accurate target for a healthy body composition.
- Focus on functional strength: Use your natural leverage. Large-framed individuals often excel in compound movements like deadlifts and squats. Lean into your natural strengths rather than fighting your anatomy.
Your skeleton is the permanent foundation of your physical self. You can change your fat levels and your muscle mass, but you cannot change the width of your pelvic girdle or the thickness of your humerus. Embracing your specific frame size is the first step toward a health plan that actually works for your unique biology.