If you’ve spent any time in a doctor’s office, you know the drill. They plug in your height and weight, the chart spits out a number, and if that number lands above 24.9, the word “overweight” comes up sometimes followed by a suggestion to lose a few pounds “for your health.”
Here’s the thing: if you’re over 65, that advice might be based on a chart that was never built with your body in mind.
Let’s talk about why.
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The Chart We All Grew Up With
Most of us know the standard BMI categories by heart at this point:
- Underweight: under 18.5
- Normal: 18.5–24.9
- Overweight: 25–29.9
- Obese: 30+
This chart has been the go-to for decades, and for younger and middle-aged adults, it’s a reasonably useful starting point. But it was built using data drawn largely from younger and middle-aged populations not from 70-, 80-, or 90-year-olds. And older bodies are genuinely different.
As we age:
- We naturally lose muscle mass (this is called sarcopenia, and it happens to some degree in almost everyone)
- Bone density shifts
- Body composition changes even when the number on the scale stays the same
- Nutritional reserves become more important because illness, surgery, and hospitalization all draw on those reserves
- We’re at much higher risk for malnutrition which in itself is a serious health condition (Read more about it here!)
So when we hold an 80 year old to the same 18.5–24.9 “normal” range as a 30 year old, we can end up flagging someone as outside normal range. When they’re actually sitting in the range associated with the best outcomes for their age group.
And on the flip side, plenty of older adults land comfortably in that “normal” range while quietly being underweight and at real risk.
So What’s the Right Range, Then?
Based on a growing body of geriatric research, a healthy BMI range for adults 65 and older looks more like 23.0 to 29.9 noticeably higher than the standard adult chart, and reaching well into what most people think of as “overweight” territory.
This isn’t one dietitian’s hot take. It shows up consistently across the research.
A large, widely cited meta-analysis pooling data across dozens of studies found what’s sometimes called the “obesity paradox” in older adults: people classified as “overweight” (BMI 25–29.9) often have equal or even lower all-cause mortality than people in the standard “normal” 18.5–24.9 range.¹ Risk tends to climb noticeably once BMI drops below 23, and again once it climbs into the mid-30s and beyond.
Other geriatric research including a well known study out of the Annals of Geriatric Medicine and Research looked at functional capacity, fall risk, muscle strength, and nutritional status across BMI groups in older adults, and consistently found the worst outcomes clustered at the lower end of the BMI spectrum, not the higher-normal end.²
Because of findings like these, geriatric and clinical nutrition guidelines including guidance from groups like ESPEN have increasingly moved toward this higher range as a more accurate “healthy” target for adults 65 and up.³ You’ll see some variation across sources (a few narrow it slightly, to something like 23–27.5), but the overall pattern holds: healthy BMI shifts up, not down, as we age.
Why Would a Higher BMI Actually Be Protective?
A few things seem to be going on here, and they all make a lot of physiological sense once you dig in.
Nutritional reserve. If someone gets sick, has surgery, or ends up hospitalized, having some extra energy and protein in reserve gives the body something to draw from. Clinically, patients who come into an illness with a little more reserve tend to weather it better than those who are already lean with nothing extra to lose.
Fall and fracture protection. A bit of extra weight along with its role in maintaining bone density appears to reduce the severity of falls and fractures, which are a massive factor in independence and mortality risk for older adults.
Muscle mass matters more than the number itself. This is an important nuance: BMI can’t tell fat from muscle. So the protective effect isn’t really about fat — it’s often that people with a higher BMI in this age group are also carrying more muscle, and muscle is enormously protective against frailty, falls, and poor recovery from illness.
Unintentional weight loss is a red flag, always. This might be the single most important practical takeaway here. Losing weight without trying even in someone technically “overweight” by the standard chart is consistently linked to worse outcomes in older adults.⁴ It’s something that should prompt a closer look, not a shrug of relief.
If You’re an Older Adult (or Caring for One)
If a provider looks at a BMI of 27 or 28 and recommends weight loss based purely on the standard adult chart, it’s worth asking whether that recommendation reflects geriatric specific guidelines. A BMI in that range may actually put you in the zone associated with the best outcomes for your age group not one that needs correcting.
That doesn’t mean weight is never worth discussing with your care team. Every person’s situation is different, and there are absolutely cases where weight loss is medically appropriate. But the blanket “get down to 18.5–24.9” advice doesn’t hold up the same way past 65, and it’s worth having a more nuanced conversation instead of defaulting to the standard chart.
And if your BMI is drifting down toward 23 or below or you’ve lost weight without trying that’s genuinely worth flagging with your doctor or dietitian, even if it might feel like “good news” by old standards.
If You’re a Dietitian Reading This
This is worth building into how you assess and educate patients, and yes, into how you chart.
A few practical shifts to consider:
- Use geriatric specific BMI ranges as your reference point when assessing older adults, not the standard adult chart
- Pair BMI with actual nutritional markers, Mini Nutritional Assessment score, recent weight trends since BMI alone has real limits at any age, but especially here. It can’t detect muscle mass, it can’t detect visceral fat, and it can completely miss sarcopenic obesity, where someone has a “normal” or even elevated BMI paired with very low muscle mass
- Watch trends, not snapshots. A stable BMI of 27 tells a very different story than a BMI that dropped from 27 to 23 over six months
- Look at other overall trends, food and fluid intake averages, independence with eating, socialization at meals, focus at meals, etc.
- Be ready to advocate. Plenty of physicians outside geriatrics are still working from the standard chart sometimes it’s on us to bring the geriatric specific evidence into the conversation
A Few Honest Caveats
BMI, even this adjusted geriatric range, still isn’t a perfect tool and it’s worth saying that plainly.
It can’t distinguish fat from muscle. It doesn’t account for where fat is distributed, and visceral fat around the organs carries a different risk profile than fat elsewhere something BMI simply can’t see. There’s also real variation by sex and by very advanced age; some research suggests the ideal range may creep even higher for adults in their 80s and 90s.
So think of 23.0–29.9 as a much better starting frame than the standard chart not a strict rulebook. Waist circumference, functional status, recent weight trends, and how someone is actually doing day to day all matter just as much, if not more. BMI is a piece of the puzzle, not the whole thing. It’s only one piece of information we use in a nutrition assessment.
BMI isn’t the entire dictator of how healthy someone is. As dietitians we can use it as one piece, use it to give estimated energy and fluid needs. But let’s not hold it up as the holy grail of health. Use it as it should be used.
The Bottom Line
The “normal” BMI range most of us grew up with 18.5 to 24.9 wasn’t built with older bodies in mind. Geriatric research consistently points to a healthier target of roughly 23.0 to 29.9 for adults 65 and older, largely thanks to the protective role of nutritional reserve, the muscle to fat relationship, and the very real dangers of unintentional weight loss in this population.
If you’re an older adult, consider this permission to have a more nuanced conversation with your care team instead of panicking over a number on a standard chart. And if you’re a dietitian, consider this your nudge to make sure geriatric-specific ranges are actually part of your everyday practice and patient education.
References
- Winter JE, MacInnis RJ, Wattanapenpaiboon N, Nowson CA. BMI and all-cause mortality in older adults: a meta-analysis. Am J Clin Nutr. 2014;99(4):875-890.
- Kıskaç M, Soysal P, Smith L, Capar E, Zorlu M. What is the Optimal Body Mass Index Range for Older Adults? Ann Geriatr Med Res. 2022;26(1):49-57. doi:10.4235/agmr.22.0012
- Volkert D, Beck AM, Cederholm T, et al. ESPEN practical guideline: Clinical nutrition and hydration in geriatrics. Clin Nutr. 2022.
- Chapelon J, Sourdet S, Angioni D, et al. Body composition of older adults with normal body mass index. Cross-sectional analysis of the Toulouse Frailty clinic. J Frailty Aging. 2025. doi:10.1016/j.tjfa.2024.100003
Want the full geriatric BMI reference sheet and more clinical resources like this one? Check out Clinical Nutrition Central.
Michelle Saari is a Registered Dietitian based in Canada. She has a Master's Degree in Human Nutritional Sciences and is a passionate advocate for spreading easy to understand, reliable, and trustworthy nutrition information. She is currently a full time online entrepreneur with two nutrition focused websites.
