You probably know the pattern. The weight comes off during a strict diet, then slowly creeps back in the months after. For many people, it feels like a personal failure.
Researchers at Case Western Reserve University may have found a biological reason it is so hard to make weight loss stick. In a 2026 study in Cell Reports, the team showed that fat cells from mice held onto a kind of "memory" of obesity.
Even after the animals lost the weight, their fat cells kept producing extra asprosin, a hormone that signals hunger to the brain.
The team then checked publicly available data from human fat tissue. The same pattern turned up there, which suggests the mechanism may also operate in people. The human part of the work is still early.
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How the memory gets stuck in fat tissue
In obesity, a signaling molecule called TGF-beta1 climbs. This brief rise reshapes the way DNA is packaged inside fat cells.
The result is a lasting switch on the gene that makes asprosin. The hunger signal keeps running for weeks after weight loss, even after TGF-beta1 itself has returned to normal.
"Imagine having an appetite-stimulating signal stuck in the 'on' position day after day, despite losing weight," senior author Atul Chopra said in a statement from Case Western. Chopra is associate professor of medicine, genetics and genomics at Case Western School of Medicine.
In the mouse experiments, blocking the asprosin pathway stopped weight regain. The team also saw that elevated TGF-beta1 in a pregnant mouse appeared to program her offspring's fat cells, making the pups more vulnerable to obesity later.
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What it could mean for people on GLP-1 drugs
The finding may help explain a frustrating experience for many patients. When people stop GLP-1 drugs like semaglutide, the active ingredient in Novo Nordisk's Ozempic and Wegovy, the hunger and much of the weight tend to come back.
If fat cells are still broadcasting a hunger signal after weight loss, stopping the medication may leave that signal unopposed. Welltica has previously covered what may help prevent regain after a GLP-1 drug.
Chopra framed the broader point in the Case Western announcement. "Obesity relapse is not a failure of willpower or discipline. It is driven by a durable biological memory," he said.
The treatment idea is still early
The team now plans to confirm the same memory in human fat tissue after weight loss. They also want to test whether drugs that block asprosin can prevent weight regain in people.
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For now the evidence rests on mouse experiments and on patterns the team spotted in existing human datasets. That is a promising starting line, not a confirmed human treatment.
Anyone thinking about changing a prescribed weight-loss medication, including stopping or restarting a GLP-1 drug, should talk to their doctor before making the switch.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.