Losing weight can bring dramatic health benefits and now researchers have a clearer picture of what’s happening inside fat tissue that may explain why.
A new study published July 9 in Nature analyzed more than 170,000 fat cells from people with severe obesity before and after weight loss surgery. The researchers found that weight loss not only increased fat metabolism but also cleared out aging and damaged cells that contribute to inflammation and poor metabolic health.
“We’ve known for a long time that weight loss is one of the best ways to treat the complications of obesity, such as diabetes, but we haven’t fully understood why,” said Dr. William Scott, lead author of the study and a researcher at the Medical Research Council Laboratory of Medical Sciences and Imperial College London. “This study provides a detailed map of what may actually be driving some of these health benefits at a tissue and cellular level.”
Participants in the study had a body mass index (BMI) over 35 and lost an average of 25 kilograms (about 55 pounds) after bariatric surgery. Researchers compared fat tissue samples taken during surgery with samples taken more than five months later.
They discovered that weight loss appears to trigger a breakdown and recycling of lipids, a process that may help the body burn more energy and reverse fat build-up in organs such as the liver and pancreas. The study also found a significant reduction in senescent cells, which are older, damaged cells that no longer function properly and promote inflammation.
“Fat tissues have many underappreciated health impacts, including on blood sugar levels, body temperature, hormones that control appetite, and even reproductive health,” Scott said. “We hope that new information from studies like ours will start to pave the way for developing better treatments for diabetes and other health problems caused by excess body fat.”
Not all changes were positive, however. The researchers found that inflammatory immune cells that had infiltrated fat tissue before weight loss didn’t fully return to normal. This “inflammatory memory” may carry long-term risks, particularly if weight is regained.
Dr. Faye Riley, research communications lead at Diabetes UK, said the study could lead to future therapies that mimic the effects of weight loss.
“For some people, losing weight can put their type 2 diabetes into remission. But weight loss is challenging, and current approaches don’t work for everyone,” Riley said. “This research offers a rare window into the changes that occur in fat tissue during weight loss that may be key to improving health and putting type 2 diabetes into remission.”
The study was funded by the Medical Research Council, Diabetes UK and Wellcome.