Here's why staying hearty can be a good thing, according to medical researchers at UCLA.
National data has shown that nearly one in five people over the age of 65 undergoes surgery each year. Many have heard the familiar refrain that losing weight beforehand will lead to better outcomes, particularly for a scenario like joint replacement surgery.
An August 2025 study delivers a counterintuitive new take. Anesthesiology and surgical researchers at University of California, Los Angeles found carrying a few extra pounds of weight could actually protect patients following surgery. The experts observed, in their words, that “being overweight was associated with lower odds of 30-day all-cause mortality.”
Published in a journal of the American Medical Association, the research tracked the health outcomes of 414 seniors, ages 65 and up, who underwent major elective surgery between February 2019 and January 2022. The patients were categorized by body mass index (BMI) and divided into five groups:
- Underweight (less than 18.5)
- Normal weight (18.5-24.9)
- Overweight (25.0-29.9)
- Obese (30.0-39.9)
- Morbidly obese (40 and above)
The researchers then tracked the rate of “death, complications, delirium, and discharge disposition” in those patients over the course of the following year.
The UCLA team concluded that “overweight” patients showed the lowest 30-day mortality rate (0.8% compared to 18.8% for normal-weight patients), while “underweight” patients bore the highest mortality rate (75%). Curious to explore deeper, the researchers then split the “normal weight” group in half, and found that almost all of the deaths and complications among that group occurred for those on the lower end of normal BMI (18.5 to 22.5).
The team recorded other noteworthy findings:
- One in 128 overweight individuals died within 30 days of their procedures, compared with 25 in 133 deaths among normal weight patients
- Three out of four underweight seniors died within a month of surgery
- Overweight patients showed the fewest overall complications (16%) compared to other weight categories
- Eight out of 10 morbidly obese patients suffered more complications compared to lower-weight groups, but did not die
The researchers say this highlights the “obesity paradox”—or the observation that under certain circumstances, being overweight or even mildly obese can be associated with better survival outcomes than those of lower weights. “This protection has been hypothesized to stem from increased physiological reserve, better nutritional status, or greater metabolic adaptability, which may provide resilience against age-related health declines and acute stressors,” the team theorizes. This may also help reinforce the growing argument that BMI is not the best metric to determine health status, as it does not account for muscle mass and other variables that are unique to each individual’s physiology and wellness.
On that note, the team also emphasizes that this does not mean obesity is protective overall. “Rather, it highlights the complexity of how weight, fat distribution, and muscle mass interact with specific disease processes and outcomes,” the study states.
The age demographic also helps highlight that higher weight or BMI is likely not advisable for younger groups. According to the Cleveland Clinic, obesity increases your risk of heart disease, diabetes, certain cancers, arthritis, kidney and liver problems, dementia, mood disorders and more. For most adults in this category, they recommend following a sustained weight loss plan, stating “weight loss of just 5% to 10% can significantly improve your health risks.”
Blood pressure, A1C, cholesterol, and waist circumference are just a few other indicators of overall health.
The study may help highlight how staying physically active for functional strength and trying to eat nutritious foods has implications even beyond those traditionally discussed, like cardiovascular health. Whether or not surgery is in your future, speak with your doctor about the best lifestyle plan for you.
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