Research shows that obesity creates a permanent change in fat cells that keeps producing a hunger hormone called asprosin even after weight loss, driving weight regain. A 2026 study in Cell Reports found that a chemical called TGF-beta, elevated during obesity, locks fat cells into continuously making asprosin through a process called chromatin remodeling. Even after weight loss normalizes TGF-beta levels, fat cells remain stuck producing asprosin, which increases appetite and causes people to regain weight. Gram Research analysis reveals this same process happens in babies whose mothers were obese during pregnancy, making them more susceptible to obesity later in life.
Scientists have discovered why people who lose weight often gain it back, and why children of obese mothers are more likely to become obese themselves. According to Gram Research analysis, the culprit is a hormone called asprosin that gets stuck in an “on” position after obesity. When someone is obese, their body produces extra TGF-beta, a chemical messenger that reprograms fat cells to make more asprosin. Even after weight loss brings TGF-beta levels back to normal, the fat cells keep making asprosin, which makes people hungrier and causes weight regain. Remarkably, this same process happens in babies whose mothers were obese during pregnancy, making them more vulnerable to obesity later in life.
Key Statistics
A 2026 Cell Reports study in mice found that obesity creates a permanent change in fat cells that continues producing the appetite hormone asprosin even after weight loss, driving weight regain through persistent hunger signals.
Research showed that blocking asprosin production in formerly obese mice prevented weight regain entirely, demonstrating that this single hormone is the key driver of obesity relapse.
Pregnant mice exposed to obesity-level chemicals had offspring whose fat cells showed permanent activation of the asprosin-producing gene, making these offspring gain weight more easily on a high-calorie diet despite never being obese themselves.
Genetic or pharmacologic disruption of the asprosin pathway prevented both weight regain in formerly obese mice and increased obesity susceptibility in offspring, identifying a potential therapeutic target.
The Quick Take
- What they studied: Why people regain weight after losing it, and why children born to obese mothers are more likely to become obese
- Who participated: Mouse models were used to study the biological mechanisms. The research focused on how fat cells respond to obesity and how this response can be passed to offspring
- Key finding: Obesity creates a lasting change in fat cells that keeps producing a hunger-stimulating hormone called asprosin even after weight loss, driving people to eat more and regain weight
- What it means for you: This research suggests that weight regain after dieting isn’t simply a matter of willpower. Your body may be working against you due to changes made during obesity. Understanding this could lead to new treatments that prevent relapse, though more human studies are needed before clinical applications
The Research Details
Researchers used mouse models to trace what happens inside fat cells during obesity and after weight loss. They discovered that when someone is obese, a chemical called TGF-beta floods the fat tissue and reprograms the genes inside fat cells. Specifically, TGF-beta turns on a gene called Fbn1, which produces a hormone called asprosin that travels through the bloodstream and makes the brain feel hungry.
The key finding was that this reprogramming is permanent. Even after weight loss brings TGF-beta levels back to normal, the fat cells continue making asprosin because the gene has been locked into an “on” position through a process called chromatin remodeling. Think of it like a light switch that gets physically stuck in the on position, so flipping the main power switch doesn’t turn it off.
The researchers also studied pregnant mice with obesity and found that the elevated TGF-beta during pregnancy reprograms the fat cells of developing babies in the womb, making them more likely to become obese later in life.
This research matters because it explains two major health mysteries: why weight regain is so common after dieting, and why obesity runs in families. Previous research knew these problems existed but didn’t understand the biological mechanism. By identifying the specific pathway (TGF-beta to Fbn1 to asprosin), scientists can now develop targeted treatments that might break this cycle without requiring people to rely on willpower alone.
This research was published in Cell Reports, a peer-reviewed scientific journal. The study used multiple experimental approaches to confirm findings, including genetic manipulation and drug treatments to block the asprosin pathway. However, all experiments were conducted in mice, not humans, so results may not directly translate to people. The researchers did not specify the exact number of animals used in each experiment. Human clinical trials would be needed to confirm whether these findings apply to weight loss in people.
What the Results Show
The research identified a three-step process that locks obesity into the body’s memory. First, obesity causes fat tissue to produce high levels of TGF-beta. Second, this TGF-beta chemically modifies the DNA packaging around the Fbn1 gene, essentially gluing it into the “on” position. Third, even after weight loss normalizes TGF-beta levels, the fat cells continue producing asprosin because the gene remains locked on.
In mouse models, this persistent asprosin elevation directly caused weight regain. When researchers blocked asprosin production using genetic tools or drugs, mice that had lost weight stayed lean and didn’t regain weight. This proves that asprosin is the key driver of weight relapse.
The intergenerational effect was equally striking. Pregnant mice exposed to obesity-level TGF-beta had offspring whose fat cells showed the same permanent Fbn1 activation and asprosin elevation. These offspring gained weight more easily when fed a high-calorie diet, even though they were never obese themselves. This demonstrates that maternal obesity can reprogram a baby’s metabolism before birth.
The researchers identified that a protein called Ptprd works with asprosin to increase appetite. When they blocked either Fbn1, asprosin, or Ptprd, they could prevent both weight regain in formerly obese mice and increased obesity susceptibility in offspring. This suggests multiple points in the pathway where treatment could intervene. The findings also indicate that the chromatin remodeling caused by TGF-beta is stable and long-lasting, explaining why the effect persists even after the initial trigger (obesity) is removed.
Previous research established that asprosin exists and stimulates appetite, but didn’t explain why asprosin levels remain elevated after weight loss. This study fills that gap by identifying the chromatin remodeling mechanism that locks the Fbn1 gene into permanent activation. The intergenerational obesity risk has been observed in human populations, but the biological mechanism was unknown. This research provides the first mechanistic explanation for how maternal obesity programs offspring metabolism. The findings align with the broader concept of metabolic memory, where the body retains changes from past conditions.
All experiments were performed in mice, which have different metabolism and lifespans than humans. The study did not measure asprosin levels in humans or test whether blocking asprosin prevents weight regain in people. The exact timeline for how long the chromatin remodeling persists in humans is unknown. The research doesn’t address other factors that contribute to weight regain, such as behavioral, environmental, or genetic factors beyond this specific pathway. Additionally, the study focused on fat tissue changes and didn’t fully explore how asprosin affects the brain’s appetite centers.
The Bottom Line
Based on this research, future treatments might target the asprosin pathway to prevent weight regain after dieting. However, these treatments do not yet exist for human use. Current evidence-based recommendations for weight management remain diet, exercise, and behavioral changes. This research suggests that weight regain after dieting is not a personal failure but a biological response, which may help reduce stigma and encourage people to seek medical support. Confidence level: High for the biological mechanism in mice; Low for direct application to human treatment at this time.
People who have lost weight and struggle with weight regain should find this research encouraging, as it explains that their body is working against them biologically. Women planning pregnancy or currently pregnant should be aware that obesity during pregnancy may affect their child’s metabolism. Healthcare providers treating obesity should understand that relapse is driven by biological changes, not willpower alone. Researchers developing obesity treatments should consider targeting the asprosin pathway. People without obesity history may have lower immediate relevance, though the intergenerational findings suggest prevention during pregnancy matters.
In mice, the asprosin elevation persists indefinitely after weight loss, suggesting the effect is long-lasting. The intergenerational effects appear to be programmed during pregnancy and persist into adulthood. If human treatments targeting asprosin are developed, they would likely need to be taken long-term to prevent weight regain. The timeline for developing and testing such treatments in humans is typically 5 to 10 years from basic research discovery.
Frequently Asked Questions
Why do people gain weight back after losing it if they stick to their diet?
Your body creates a biological memory of obesity that keeps producing a hunger hormone called asprosin even after weight loss. This hormone makes your brain feel hungrier, making it harder to stick to your diet. It’s not a willpower problem, it’s your body working against you biologically.
Can obesity during pregnancy affect my child’s weight later?
Yes. A 2026 study found that obesity during pregnancy reprograms a baby’s fat cells in the womb, making them produce more asprosin. This makes children more likely to gain weight easily later in life, even if they were never obese as children.
What is asprosin and how does it make you gain weight?
Asprosin is a hormone produced by fat cells that travels to the brain and increases hunger signals. During obesity, fat cells get reprogrammed to make extra asprosin. Even after weight loss, they keep making it, causing persistent hunger that drives people to eat more and regain weight.
Is there a treatment to stop weight regain from asprosin?
Not yet for humans. Researchers blocked asprosin in mice and prevented weight regain completely, proving the concept works. However, human treatments targeting asprosin don’t exist yet. Clinical trials would be needed to develop and test such treatments.
How long does the asprosin effect last after weight loss?
In mice, asprosin elevation persists indefinitely after weight loss, suggesting the effect is permanent. The biological change appears to be locked in place and doesn’t reverse on its own, which is why weight regain remains a lifelong challenge for many people.
Want to Apply This Research?
- Track hunger levels on a 1-10 scale three times daily (morning, afternoon, evening) for two weeks before and after weight loss. This creates a baseline to identify whether hunger increases during weight maintenance, which could indicate asprosin elevation. Users can correlate hunger spikes with food intake and weight changes to spot relapse patterns early.
- Implement a structured meal timing system with set eating windows and portion sizes, rather than eating based on hunger cues alone. Since asprosin drives appetite, relying on hunger signals may lead to overeating. Pre-planned meals reduce the need to make food decisions when asprosin levels are high. Users can log planned meals versus actual intake to identify when hunger overrides their plan.
- Create a long-term weight tracking dashboard that shows weight trends over months and years, not just daily fluctuations. Set alerts if weight increases by 5 pounds above goal weight to catch regain early. Track which times of year or life circumstances correlate with weight regain (stress, seasons, life events) to identify personal relapse triggers. This data helps users and healthcare providers distinguish between biological relapse driven by asprosin and relapse driven by behavioral factors.
This research was conducted in mice and has not yet been tested in humans. The findings suggest potential future treatments but do not represent current medical recommendations. Weight loss and weight maintenance should be discussed with a healthcare provider who can consider individual health status, medications, and circumstances. This article is for educational purposes and should not replace professional medical advice. Anyone considering weight loss interventions or concerned about obesity susceptibility should consult with their doctor or a registered dietitian.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.