- Researchers say a new study indicates that a disconnect between the brain and the gut may be a reason that people tend to gain weight after initially losing weight.
- They say in many people who have lost weight their gut will tell them they’re full after eating a meal, but their brain will try to tell them they’re still hungry.
- Experts say the disconnect may be due to the body’s attempt to store fat during weight loss.
Nearly half of adults in the United States try to lose weight each year, but many will not keep that weight off long-term.
In fact, only about one in five people who are overweight can maintain weight loss for a year or longer, research shows.
While there are many competing theories about why that is, ranging from psychological to biological, a new study of children with obesity suggests the answer might lie in a disconnect between gut hormones and brain signals.
Researchers at Seattle Children’s Hospital in Washington put children with obesity on a 24-week weight loss program, monitoring their brain activity and gut hormone responses before and after the trial.
At the end of the weight loss program, the researchers reported that after eating a meal the children’s gut showed normal levels of regulatory hormones indicating that they were full and satisfied.
Their brains, however, showed levels of activity signaling that they were still hungry.
The researchers also found that the more weight a child lost, the more likely they were to react to food cues after completing a meal —their brain essentially telling them they were still hungry while their gut was telling them the reverse.
“Our results imply that during weight loss intervention, your body acts to conserve fat through maintaining hunger responses in the brain and that this needs to be addressed,” Dr. Christian Roth, a lead study author and professor at Seattle Children’s Hospital, said in a press release.
Roth said larger, more extensive studies would be required to confirm these findings.
“It would also be useful to investigate how long the disconnect between central and local appetite regulation persists after maintained weight loss, to guide intervention plans,” he added.
“This is a very interesting study and I think that a lot of these findings are applicable to adults as well,” said Dr. Mir Ali, a bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in California.
“I see in my patients that they feel the need to eat, even if their stomach feels full,” Ali told Healthline. “There is certainly a strong psychological component to eating behavior that surgery and medications cannot always address completely.”
“I feel this research is on the right track and we need to find a way to satisfy the brain as well as the gut,” he added. “This will require extensive research in both children and adults to find the right solution.”
One of the more notable aspects of the study is how it complicates our understanding of how hormones affect appetite and rebound weight gain.
Previous studies have shown that an increase in appetite hormones after weight loss might be a key driver of these rebound gains.
The results of this study paint a more nuanced picture where even if gut hormones are normal, the brain is out of sync.
“The study underscores our understanding of obesity and weight homeostasis as a chronic disease of the brain,” said Dr. Mert Erogul, an attending physician at Maimonides Medical Center in New York.
“The regulation of appetite is enormously complex and layered,” he told Healthline. “From the digestive tract, there are hormones that signal fullness, such as leptin, CCK, and peptide YY. There are also hormones that signal hunger, such as ghrelin. These are in constant interplay with seemingly subjective feelings that come from the brain such as food preference and liking as well as motivation to eat.”
Ultimately, experts say this may require a holistic approach to weight loss and maintaining a healthy weight.
“Rebound weight gain is very common and happens for many physiological, behavioral, and psychological reasons,” said Dr, Steve Patching, a medical director of bariatric surgery at Sutter Hospital in Sacramento, California.
“Believe it or not, weight loss actually sets up your body for weight gain,” he told Healthline. “This is because the body always strives for symbiosis. This is why we often still feel hungry or even starving after we eat a ‘normally satiating’ meal. It is also why correct weight loss should be done slower than we often want.”
“Weight loss needs to occur in the context of a durable commitment to changes in diet and lifestyle,” he said. “Even then, obesity medicine specialists recognize that people who are overweight often need lifelong therapy with medications to maintain weight loss.”