People aged 75 and older who weighed the same as they did several years earlier faced a 41% higher risk of death if their weight had fluctuated sharply in between, a study found.
A research team led by professors Suh Ji-yeon and Choi Ji-min of the gastroenterology department at Seoul National University Hospital Healthcare System Gangnam Center, together with professor Han Kyung-do of Soongsil University, analyzed the relationship between the size of weight fluctuations and mortality risk using National Health Insurance Service checkup data. The findings were published in the international journal Scientific Reports, the hospital said on the 23rd.
The team tracked 616,696 people aged 75 and older who underwent health checkups between 2012 and 2015 and had at least four weight records, following them through the end of 2022. Earlier studies focused mainly on how much weight was gained or lost, while this one examined the ups and downs across multiple measurements.
The average age of the participants was 78, and the median follow-up period was 7.5 years. During that time, 195,585 people died, or 31.7% of the total.
The team divided the participants into four groups based on the size of their weight fluctuations. Compared with the group with the smallest fluctuations, the other three groups showed mortality risks that were 12%, 26% and 62% higher as the swings grew larger. The figures were adjusted for age, sex, lifestyle, coexisting conditions and other factors that could affect mortality risk.
Differences also appeared within the "maintained" group, whose first and last weights differed by no more than 5%. Those whose weight changed sharply in between faced a 41% higher risk of death than those who held relatively steady. Among participants who lost weight, those with large fluctuations faced a 36% higher risk than the rest, and among those who gained weight, the figure was 33%. Large fluctuations refer to the top 25% of all participants by the size of their weight swings.
Because the study was an observational analysis of health checkup data, it cannot establish weight fluctuation as a direct cause of death. Illness or frailty may have influenced both weight changes and mortality risk.
"If the first and last weights are similar, it is easy to assume there was no major change, but the changes in between also need to be examined," professor Suh said. Professor Choi added that for older adults whose weight changes sharply, "there is a need to pay attention to whether illness or a change in nutritional status lies behind it."
Earlier research has also examined the link between weight fluctuation and health. In a study reported in July 2019, a team from the family medicine department at Seoul National University Hospital analyzed about 264,000 men and women aged 40 and older and found that the group with the largest weight changes had a 33% higher risk of death from all causes than the group with the smallest.
A team led by professor Ryu Ji-won of Seoul National University Bundang Hospital and professor Yoon Hyung-jin of Seoul National University Hospital tracked about 3.6 million people aged 40 to 65 for 10 years and reported in October 2024 that weight fluctuations of 10% or more raised dementia risk by up to twofold. Pennsylvania State University published an analysis of 4,304 people aged 65 and older in the journal Obesity in July 2025, finding that the group with large weight fluctuations experienced cognitive decline two to four times faster.