Healthy weight for a 5'6 woman: Why the BMI chart is often wrong

Honestly, if you've ever spent a panicked afternoon staring at a generic BMI chart in a doctor’s office, you know the vibe. It feels a bit like trying to fit a square peg into a round hole. You're 5'6". You're wondering if that number on the scale is "okay" or if you need to start eyeing those overpriced green juices. But here is the thing: a healthy weight for a 5'6 woman isn't just one static number, and it definitely isn't the same for a marathon runner as it is for someone who works a 9-to-5 desk job.

Most medical resources will point you straight to the Body Mass Index. For a woman standing 5 feet 6 inches tall, the "normal" BMI range—which is a calculation of weight-to-height ratio—is typically cited as being between 115 and 154 pounds.

That is a nearly 40-pound spread.

Why is it so wide? Because bodies are weird. They're made of bone, water, muscle, and fat, and the scale doesn't know the difference between a pound of heavy-hitting muscle and a pound of visceral fat. If you've got a larger frame or a lot of lean muscle mass, you might weigh 160 pounds and be "healthier" by every metabolic metric than someone who weighs 120 pounds but has very little muscle.

The BMI trap and what it misses

The Body Mass Index was actually created in the 19th century by a Belgian mathematician named Adolphe Quetelet. He wasn't even a doctor. He was looking for a way to measure the "average man" for social statistics. It was never meant to be a diagnostic tool for individual health. Yet, here we are, over 150 years later, still using it as the gold standard.

If you are 5'6", your BMI is calculated by taking your weight in kilograms and dividing it by your height in meters squared. Or, more simply: $Weight(lb) \times 703 / Height(in)^2$.

But let's talk about the flaws.

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A 2016 study published in the International Journal of Obesity looked at over 40,000 people and found that nearly half of those classified as "overweight" by BMI were actually metabolically healthy. On the flip side, many people in the "normal" range had high blood pressure, high cholesterol, or insulin resistance. If you’re a 5'6" woman with a "sturdy" build—think broad shoulders or dense bones—the BMI might label you as overweight when your heart and lungs are actually in peak condition.

Body composition is the real MVP

Muscle is roughly 15% denser than fat. This is why two women can both be 5'6" and weigh 150 pounds, but one wears a size 6 while the other wears a size 10.

If you're lifting weights three times a week, you’re likely packing on "heavy" tissue that burns more calories at rest. That’s good. That’s what we want. In this case, chasing a lower number on the scale might actually be counterproductive because you’d be losing the very muscle that keeps your metabolism humming.

How to find your "real" healthy weight

So, if the BMI is a bit of a blunt instrument, how do you actually figure out what a healthy weight for a 5'6 woman looks like for you?

Medical experts like those at the Mayo Clinic and the Cleveland Clinic are increasingly looking at other markers. One of the most telling is the waist-to-hip ratio. Generally, for women, a waist circumference of more than 35 inches is linked to a higher risk of heart disease and type 2 diabetes, regardless of what the total weight is.

You could also try the "string test." It sounds "kinda" DIY, but it's surprisingly accurate. Take a piece of string that is exactly your height (66 inches). Fold it in half. Can you comfortably wrap that halved string (33 inches) around your waist? If you can, you're likely in a healthy range for visceral fat.

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Considering your "frame" size

Frame size is a real thing. It’s not just an excuse people use at Thanksgiving. You can actually check yours by wrapping your thumb and middle finger around your wrist.

• If they overlap, you have a small frame.
• If they just touch, you’re medium.
• If there is a gap, you’ve got a large frame.

For a 5'6" woman with a large frame, a healthy weight might naturally sit at the higher end of the 145–155 lb range. For someone with a tiny frame, 120 lb might feel more natural.

Age, hormones, and the 5'6" reality

Let's be real: your "healthy" weight at 22 is rarely your healthy weight at 52.

As women age, especially as we hit perimenopause and menopause, our bodies naturally shift. Estrogen drops. We lose muscle mass more easily (sarcopenia). The body starts to hoard fat around the midsection to protect organs and produce a small amount of backup estrogen.

If you are 5'6" and 55 years old, being 155 pounds might actually be "healthier" than being 125 pounds. Why? Because a little extra weight in older age can provide a "buffer" against bone loss and osteoporosis. It’s about resilience, not just aesthetics.

The role of "Set Point Theory"

There is this idea in biology called the Set Point Theory. Essentially, your body has a weight range it really likes to stay in. For some 5'6" women, that might be 140 pounds. For others, it’s 158. When you try to force your body below that set point through extreme dieting, your hormones—specifically leptin and ghrelin—go haywire. You get hungrier. Your metabolism slows down. Your body fights you.

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Finding your healthy weight often means finding the weight where you feel energetic, your periods are regular (if you're pre-menopausal), your blood work is clean, and you aren't thinking about food every five minutes.

Metabolic health: The metrics that actually matter

Forget the scale for a second. If you want to know if you're at a healthy weight, look at these numbers instead:

1. Blood Pressure: Ideally under 120/80.
2. Fast Blood Glucose: Looking for under 100 mg/dL.
3. Triglycerides: Ideally under 150 mg/dL.
4. HDL Cholesterol: Higher is better (over 50 mg/dL for women).

If these numbers are in the green, and you are 5'6" and 165 pounds, you are likely metabolically healthy. You're "fit fat," as some researchers call it. It is much better for your long-term health to be slightly heavier and active than thin and sedentary.

Actionable steps to find your balance

Stop obsessing over the 115-154 lb bracket. It’s too broad to be useful and too narrow to be human. Instead, focus on these shifts:

• Prioritize protein and resistance training. Instead of trying to "lose weight," try to "change composition." Aim for 25–30 grams of protein at every meal to protect your muscle.
• Track your energy, not just your calories. If you're at 130 lbs but you're constantly exhausted and cold, you might be underweight for your specific biology.
• Measure your waist once a month. It’s a better indicator of health risks than the scale. Aim to keep it under 35 inches.
• Get a DEXA scan or a bioelectrical impedance scale. These aren't perfect, but they give you a better idea of your body fat percentage. For women, a healthy range is typically 21% to 32%.
• Listen to your joints. Carrying excess weight can be hard on the knees and hips, even if your blood work is perfect. If your joints ache, a 5% reduction in body weight can significantly reduce pressure.

A healthy weight for a 5'6 woman is ultimately the weight that allows you to live your life without being sidelined by fatigue or chronic illness. It’s the weight where you can carry your groceries, climb a flight of stairs, and enjoy a meal without a side of guilt.

Focus on how your body functions. The number on the scale is just one tiny data point in a much larger, much more interesting story.

Next Steps for Your Health Journey

1. Schedule a metabolic panel: Ask your doctor for a fasting glucose and lipid profile to see how your body is actually processing energy.
2. Calculate your waist-to-height ratio: Divide your waist circumference by your height. A ratio of 0.5 or less is generally considered healthy.
3. Audit your strength: If you can't perform basic functional movements like a squat or a plank, focus on building strength rather than cutting calories.