By Vishwadha Chander

(Reuters Health) – Excess weight gained during the adult years may speed up lung “aging,” a large, multi-country study suggests, but losing weight might have the opposite effect.

For two decades, researchers followed more than 3,000 adults recruited at ages 20 to 44. For most, packing on pounds over time was associated with an acceleration in the natural lung capacity decline that comes with age.

But when younger adults were obese at the outset and lost weight over time, they ended up with similar lung capacity to people who started out normal-weight and remained that way, the researchers report in Thorax.

“This is the first study to analyze effects weight change has on lung function over a 20-year period, and in a varied population sample,” study coauthor Gabriela Prado Peralta, a researcher at the Barcelona Institute of Global Health, told Reuters Health by email.

Lung function is a strong marker of overall health and predicts mortality in the general population, Peralta and colleagues write. Understanding just how much weight change might improve or worsen lung capacity is important as more people around the world are becoming overweight or obese.

Two mechanisms likely explain how weight gain causes a decline in lung function, Peralta said. First, more chest and abdomen fat mass will limit room for the lung to expand during inhalation. Second, fat tissue is a source of inflammatory substances that can damage lung tissue and reduce airway diameter.

Peralta and colleagues analyzed data from the European Community Respiratory Health Survey, a large population-based study that has been tracking the health of over 10,000 adults in 11 European countries and Australia for decades.

The current analysis included 3,673 participants who were followed from 1991-1993 until 2010-2014 when they were 39-67 years old.

Participants’ body weight and lung function were recorded at three points over those years, and researchers gathered information on factors that could also influence lung function, such as smoking history and asthma diagnoses.

When the study began, 12% of the participants were underweight, 57% were normal-weight, 24% were overweight and 6% were obese.

In the follow-up years, 4% of the sample lost weight, 34% maintained their weight, 53% experienced moderate weight gain and 9% had gained significant amounts of weight.

“Among participants who were in the normal weight, overweight or obese categories in young adulthood, moderate to high weight gain was associated with faster lung function decline over the study period,” Peralta said.

In contrast, people who were obese in young adulthood had poorer lung function than their normal-weight peers, but losing weight appeared to reverse the negative effects of obesity on lung function, she noted.

The findings add to a holistic way of looking at the damage done by weight gain, said Dr. Susan Renda, an assistant professor at the Johns Hopkins School of Nursing in Baltimore who wasn’t involved in the study.

“When we ask how obesity could impact lives, the average person would say it causes heart disease, diabetes or arthritis, not that their lungs aren’t going to be as strong,” she said in a phone interview.

Renda, who has been a nurse for 40 years, noted that the study showed deterioration in lung function was reversible.

“Sometimes, we think things go beyond a point of no return, but it was interesting that, across ages, the authors saw improvement.”

SOURCE: Thorax, online February 25, 2020.