A member recently shared something worth celebrating in their SGPT check-in:
“I’ve officially moved from obese to overweight on the BMI chart!”
That moment deserved a round of applause. Because while BMI isn’t perfect, that change usually signals a genuine improvement in health, less fat mass, better blood pressure, more energy, and a body under less strain.
But like any single number, BMI only tells part of the story. Let’s unpack what it actually measures, what it misses, and how we track progress more accurately at The Lab Liverpool.
What BMI Actually Tells You (and Why It Still Matters)
BMI - short for Body Mass Index, is simply your weight divided by your height squared.
It was created to look at population-level trends, not to label individuals. Still, it can highlight when someone’s carrying more (or less) tissue than is ideal for health.
What Large-Scale Research Shows
When scientists have studied millions of people worldwide, a few clear patterns appear:
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People in a BMI range of around 22-24 tend to live the longest and experience the lowest risk of disease.
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Once BMI climbs above 25, the chances of developing heart disease, type 2 diabetes, or dying early start to rise.
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Every 5-point jump above 25, for example, 25 → 30, increases that risk by about 40 %.
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Very low BMI can also increase risk, often because it reflects muscle loss, under-nutrition, or illness rather than good health.
In short: moderation wins. For most adults, bringing BMI down from the obese to overweight category means the body is functioning more efficiently, blood pressure often improves, inflammation drops, and daily movement feels easier.
Why BMI Isn’t the Full Picture
1) Muscle Mass Matters
BMI doesn’t know the difference between fat and muscle.
If you strength-train, you might weigh more than you look. A muscular 80 kg lifter at 175 cm tall can read as “overweight” on BMI, yet carry far less body fat than average.
At The Lab we see this often, clients gain muscle, drop inches from their waist, but BMI barely moves. That’s progress, not a problem.
2) Where You Store Fat Is Key
Not all body fat acts the same. Fat around your organs (visceral fat) is far more harmful than fat under the skin. That’s where waist measurements or waist-to-height ratio (WHtR) come in.
Research shows WHtR predicts risk better than BMI alone:
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A large BMJ review found that as waist size increased relative to height, risk of heart disease and early death climbed sharply.
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Another analysis reported that people with a waist larger than 0.58 × height had around one-third higher risk of cardiovascular disease and almost 70 % higher risk of diabetes.
Quick tip: Keep your waist under half your height.
If you’re 180 cm tall, aim for a waist below 90 cm. It’s a simple, evidence-based target that tracks with better health outcomes.
3) Age, Sex & Ethnicity Change the Context
Health isn’t one-size-fits-all.
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South Asian, Chinese, and Middle Eastern populations face higher metabolic risk at lower BMIs, so their healthy cut-offs are slightly lower.
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Older adults may sit in a slightly higher “ideal” range since very low BMI can mean muscle loss, which raises fall and frailty risk.
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Women naturally carry more essential fat than men, so identical BMI values don’t always represent the same body composition.
4) Normal BMI ≠ Healthy Automatically
Some people sit in the “healthy weight” range but still show poor blood sugar, high blood pressure, or low muscle mass, what researchers call metabolically unhealthy normal weight.
That’s why good health assessment needs a combination of indicators: BMI, waist size, blood pressure, fitness, and lifestyle habits.
How We Track Progress at The Lab
At The Lab, we treat BMI as one piece of the puzzle.
When we review check-ins, we look for consistency across several markers:
| Marker | Why It Matters |
|---|---|
| Waist-to-Height Ratio (WHtR) | Best quick measure of harmful belly fat. Target < 0.5 x height. |
| Blood Pressure / Resting Heart Rate | Direct sign of cardiovascular fitness and stress recovery. |
| Strength & Performance | If lifts or conditioning numbers improve, muscle and health are trending up. |
| Progress Photos / Clothing Fit | Visual and practical proof of recomposition. |
| Energy & Sleep Quality | Low energy or poor sleep can flag under-recovery or under-fueling. |
Coach’s Take
“BMI is like a dashboard light, useful for spotting change, but not enough to judge the whole engine.
When someone’s BMI drops because they’re training, eating well, and getting stronger, that’s exactly the type of progress we want to see.
But if it falls because they’re under-eating or losing muscle, we step in fast.”
What You Can Track Today
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Calculate BMI - it’s a starting point, not a verdict.
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Measure your waist & height - divide waist by height; keep it under 0.5.
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Track strength - lifts, wattage, or even bodyweight exercises.
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Monitor blood pressure if possible - steady reductions show heart health improving.
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Check in with how you feel - better energy, sleep, and recovery count as real progress.
The Big Picture
BMI can still be useful, especially when it’s trending in the right direction, but it’s not the finish line.
Pair it with waist measurements, strength data, and how you actually feel day-to-day, and you’ll get a far clearer view of your health.
If you’ve moved from obese to overweight, that’s a win worth celebrating.
You’ve taken measurable steps away from preventable health risks, and towards a body that performs better, lasts longer, and feels stronger.
Want help measuring what really matters?
If you’d like a more complete picture of your health, book a Small Group or 1-to-1 Personal Training session at The Lab Liverpool.
We’ll help you track the numbers that count, strength, movement, and confidence, not just what the scale says.
References
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Aune D. et al. (2016). Body mass index, abdominal fatness, and the risk of all-cause mortality: systematic review and dose-response meta-analysis of 230 cohort studies with 10 million participants. BMJ, 353:i2156.
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Bhaskaran K. et al. (2018). Body-mass index and cause-specific mortality in 3.6 million adults: pooled analysis of 239 prospective studies. Lancet Diabetes Endocrinol, 6(12), 944–953.
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Jayedi A. et al. (2020). Central fatness and all-cause mortality: systematic review and dose-response meta-analysis of prospective studies. BMJ, 370:m3324.
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Huang X. et al. (2025). Association between waist-to-height ratio and mortality from all causes and specific diseases: a dose–response meta-analysis of prospective cohort studies. Frontiers in Nutrition, 8:1614347.
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Caleyachetty R. et al. (2021). Ethnicity-specific BMI cut-offs for type 2 diabetes risk in the UK: cross-sectional analysis of 1.5 million adults. Lancet Diabetes Endocrinol, 9(9), 672–685.
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Winter J. et al. (2014). Body mass index and mortality in older adults: a meta-analysis of cohort studies. J Am Geriatr Soc, 62(3), 512–519.
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Bergman P. et al. (2022). Metabolically healthy obesity and risk of cardiovascular disease and mortality: a population-based cohort study. BMC Public Health, 22:13082.
