A healthy weight for a 75-year-old woman is higher than most people expect. Research on older adults consistently shows that carrying a bit of extra weight is protective, not harmful. For a woman of average height (roughly 5’3″ after accounting for age-related height loss), the weight range linked to the best health outcomes falls approximately between 150 and 200 pounds, corresponding to a BMI of roughly 27 to 35. That’s well above what standard BMI charts call “normal.”
Why the “Ideal” Weight Shifts Upward After 70
The standard BMI categories everyone knows, where 18.5 to 24.9 is “normal” and 25 to 29.9 is “overweight,” were designed for younger adults. They don’t translate well to people over 70. A large longitudinal study of adults aged 70 and older found a clear U-shaped relationship between BMI and death risk: people at the low end and the very high end fared worst, while those in the middle did best. For women, the lowest mortality risk occurred at a BMI of approximately 31.7, and a broad range of 30 to 35 was well tolerated. For men, it was lower, around 28.8.
A separate review in the Annals of Geriatric Medicine and Research confirmed this pattern, finding that older adults with a BMI below 25 or above 35 had the highest rates of functional decline, balance problems, falls, and loss of muscle strength. The study suggested that a BMI between 25 and 35 is optimal for health in older adults, with the sweet spot for older women around 31 to 32.
What These Numbers Look Like in Pounds
Because BMI depends on height, your target weight range depends on how tall you are now. Women lose an average of about 5 centimeters (roughly 2 inches) of height by age 70, and up to 8 centimeters (about 3 inches) by age 80, compared to their height at age 30. That shrinkage alone artificially inflates BMI by about 1.6 to 2.6 points, which is one reason the standard charts become misleading.
Here’s what a BMI range of 25 to 35 looks like in actual pounds at common heights for women in their mid-70s:
- 5’0″ (152 cm): approximately 128 to 179 lbs
- 5’2″ (157 cm): approximately 136 to 191 lbs
- 5’4″ (163 cm): approximately 145 to 204 lbs
- 5’6″ (168 cm): approximately 155 to 217 lbs
These ranges are broader than what you’d see on a chart designed for a 40-year-old, and that’s the point. A 75-year-old woman who weighs 170 pounds at 5’2″ is not in danger from her weight. She may actually be in a protective range.
Why Being Too Thin Is a Bigger Concern at 75
For younger adults, health messaging focuses almost entirely on the risks of excess weight. At 75, the equation flips. Being underweight or even “normal weight” by younger standards carries serious risks that often outweigh the risks of carrying extra pounds.
The core issue is muscle. The body naturally loses muscle mass with age, a process called sarcopenia. When an older woman is thin, she’s more likely to have dangerously low muscle reserves. Muscle is what keeps you upright, prevents falls, and gives your body the raw materials (amino acids) it needs to recover from illness, fight infection, and heal wounds. Women who are frail, identified by unintentional weight loss, weakness, slow walking speed, and low energy, face significantly higher rates of recurrent falls, hip fractures, and death. Once muscle reserves are depleted, even aggressive nutritional support struggles to reverse the damage.
Simple physical tests can signal whether muscle loss is becoming a problem. Walking speed below about 0.8 meters per second (taking more than 5 seconds to walk 4 meters), needing 13.5 seconds or more to stand up from a chair, walk 3 meters, turn around, walk back, and sit down, or being unable to stand from a seated position five times without using your arms are all red flags.
Waist Size Still Matters
While the scale number matters less at 75 than it did at 45, where you carry your weight still matters. Belly fat is more metabolically active and more strongly linked to heart disease and diabetes than fat stored in the hips or thighs. For women of any age, a waist circumference of 35 inches (88 cm) or more is associated with increased risk. Between 31.5 inches (80 cm) and 35 inches is a moderate-risk zone.
A large meta-analysis of over 58,000 adults aged 65 to 74 found that even among women classified as overweight by BMI, a large waist circumference carried higher mortality risk. So two women at the same weight can have very different risk profiles depending on their body shape. A tape measure around the waist, taken at the navel, gives you information the bathroom scale simply can’t.
Protein Intake and Keeping Muscle
Maintaining a healthy weight at 75 isn’t just about how much you eat. It’s heavily about what you eat, particularly protein. The official recommendation for all adults is 0.8 grams of protein per kilogram of body weight per day, but experts in aging nutrition call this inadequate for older adults. They recommend 1.2 to 2.0 grams per kilogram per day. For a 160-pound (73 kg) woman, that translates to roughly 88 to 146 grams of protein daily.
Spreading protein evenly across meals matters too. The body’s ability to use protein for muscle building peaks at about 35 grams per meal in older adults. Eating most of your protein at dinner, as many people do, means your muscles miss out on building opportunities at breakfast and lunch. Three meals each containing 30 to 35 grams of protein is more effective than one large serving.
When Weight Loss Is and Isn’t Recommended
For decades, doctors hesitated to recommend weight loss for anyone over 65 because studies showed that losing weight was associated with higher death rates. The problem with those studies was that they lumped together people who lost weight intentionally (through diet and exercise) with those who lost weight because they were sick. Unintentional weight loss at 75 is one of the strongest predictors of serious decline and should always be investigated.
More recent evidence, reviewed by the USDA’s Dietary Guidelines Advisory Committee, has untangled the two. Intentional weight loss among overweight and obese older adults is associated with reduced development of type 2 diabetes, improved cardiovascular risk factors, and a reduced risk of mortality. Weight gain, on the other hand, increases risk across several health outcomes.
The practical takeaway: if you’re at 75 with a BMI over 35, losing some weight through a structured plan that includes strength training and adequate protein is likely beneficial. If your BMI is between 25 and 35, maintaining your current weight and focusing on staying physically strong is a better goal than trying to get thin. And if your BMI is under 25, gaining weight, particularly muscle, is worth pursuing actively.