For those starving themselves to cut calories but still not seeing results – you’re not alone.
Ottawa University researchers have identified a distinct group of obese people who are especially resistant to losing weight from diet changes alone, according to a report published Wednesday in the Lancet’s eBioMedicine journal.
The findings contradict a long-held belief that diet alone is enough to achieve significant weight loss, with exercise as an adjunct treatment to enhance the benefits of healthy eating.
“If you look at a large group of overweight people trying to lose weight, they don’t respond very well to exercise. But now we have discovered that people in this [diet-resistant] obesity phenotype really,” said endocrinologist Dr. Robert Dent, who collaborated with Ottowa colleagues Drs. Mary-Ellen Harper, Chantal Pileggi and Ruth McPhereson on the study.
“What the findings tell us is that when we see obese people who don’t respond to dietary restrictions, they need to be switched to physical activity,” Dent explained in a statement to the university’s editorial board.
Those who are believed to have “diet-resistant” obesity fall in the bottom 20% for the rate of weight loss while following a low-calorie diet. Those are the people for whom exercise should be a priority, the doctors argue.
Based on clinical data from more than 5,000 patients, 20 such women were asked to participate in an exercise regimen designed to analyze changes in skeletal muscle metabolism – a critical indicator of metabolic patients’ health.
Fat metabolism in skeletal muscle is regulated by the mitochondria, and those with “diet-resistant” obesity show lower mitochondrial activity in their bones than those with “diet-sensitive” obesity, the researchers said.
Participants received a total of 18 training sessions, three times a week for six weeks, using treadmills and weightlifting.
For the group that already had a mitochondrial deficit, exercise was found to boost activity in skeletal muscle, while those with comparably higher mitochondrial activity at the start of the experiment saw no added benefits in that regard.
For decades, “diet-resistant” patients have been accused of not sticking to a low-calorie meal plan, based on a lack of pounds. Now researchers hope that their new approach will lead to more personalized care.
“It is exciting and important work. These findings have clinical implications and reveal molecular mechanisms that will drive research for many years to come,” said Harper, whose team hopes to relaunch their study with an even larger cohort soon.
Obesity has been called an epidemic here in the US, where more than a third of adults (41.9%) ages 20 and older are overweight, according to statistics from the Centers for Disease Control. Add to this overweight adults who are just under clinical obesity and the percentage rises to a whopping three quarters (73.6%).
The consequences of too much weight are significant – with an increased risk of developing deadly and debilitating diseases across the board, including diabetes, heart disease, musculoskeletal disorders and various cancers. The condition is also known to weaken the immune system, making overweight people more susceptible to diseases, such as COVID-19.
“For those individuals who are obese and have had tremendous difficulty losing weight, the message to them is, you are in a group of individuals for whom exercise is particularly important,” McPhereson added. “And that’s really going to help you lose weight.”