A new two-part drug called CagriSema caused weight loss in rats primarily by reducing appetite rather than speeding up metabolism, with reduced food intake accounting for 86% of the weight loss effect. According to Gram Research analysis, when the drug was stopped, rats rapidly regained weight, suggesting that continuous treatment would be needed to maintain weight loss in humans. The drug worked by keeping hunger low while preventing the metabolic slowdown that normally occurs during dieting.
Scientists tested a new two-part drug called CagriSema on obese rats to see how it helps them lose weight and keep it off. According to Gram Research analysis, the drug worked by making rats feel less hungry rather than burning more calories. When researchers stopped giving the drug, the rats quickly gained the weight back, suggesting people would need to keep taking it to maintain weight loss. The study shows how the drug affects the body’s energy balance in different phases over time.
Key Statistics
A 2026 study in rats found that CagriSema reduced food intake by enough to account for 86% of weight loss, while only 14% came from increased calorie burning.
Research on CagriSema showed that rats regained weight within 4 weeks of stopping the drug, with metabolic adaptation reversing in approximately 7 days.
In a 6-week rat study, CagriSema maintained resting and sleeping energy expenditure while reducing food intake, preventing the metabolic slowdown seen in rats on restricted diets alone.
The Quick Take
- What they studied: How a new obesity drug called CagriSema affects weight loss, weight maintenance, and what happens when you stop taking it
- Who participated: Male rats that were overweight from eating a high-fat diet. The study compared rats getting the drug to rats on restricted diets and control rats receiving no treatment
- Key finding: CagriSema caused weight loss mainly by reducing how much rats wanted to eat (86% of the effect), while only 14% came from burning more calories. When the drug stopped, rats quickly regained weight
- What it means for you: This suggests the drug might help people lose weight by reducing appetite rather than speeding up metabolism. However, stopping the drug led to rapid weight regain, meaning ongoing treatment may be necessary to keep weight off
The Research Details
Researchers gave male obese rats either the new drug CagriSema, a calorie-restricted diet matching the drug’s weight loss results, a diet matching the drug’s food intake, or no treatment. They measured how much the rats ate and how many calories they burned using special equipment that tracks breathing patterns. The study lasted 6 weeks of treatment followed by 4 weeks after stopping the drug.
The researchers divided the results into four time periods to see how the drug’s effects changed. Phase I covered the first 10 days when weight loss was fastest. Phase II was days 11 to 42 when weight stayed stable. Phase III was the 10 days right after stopping the drug. Phase IV was the final 16 days when the body adjusted to no longer having the drug.
This approach let scientists understand not just whether the drug worked, but exactly how it worked and what happened when people stopped taking it.
Understanding how a weight loss drug actually works is crucial for predicting how it will perform in humans. By measuring both food intake and energy expenditure separately, researchers could pinpoint whether the drug works by making people less hungry or by speeding up metabolism. This information helps doctors and patients understand what to expect and whether the drug needs to be taken long-term
This was a controlled laboratory study using animals, which allows precise measurement of food intake and calorie burning that would be difficult in humans. The researchers used multiple comparison groups, which strengthens the findings. However, results in rats do not always translate directly to humans, and the study did not include female rats, which may respond differently to the drug
What the Results Show
During the first 10 days of treatment, CagriSema caused rapid weight loss, and this loss came almost entirely from rats eating less food. Their calorie burning stayed about the same as untreated rats, while rats on restricted diets burned fewer calories as their bodies adapted to eating less. This shows the drug’s main power is appetite suppression, not metabolism boosting.
From day 11 to day 42, the rats maintained their weight loss. All groups reached a metabolic steady state, meaning their bodies had adjusted to the new weight. The drug continued to work by keeping food intake low while preserving the amount of calories burned, especially during rest and sleep.
When the drug stopped on day 43, rats immediately started eating much more and gained weight rapidly. Within 4 weeks, their bodies had fully adjusted back to normal, and weight gain returned to the rate it had been before treatment started. The metabolic adaptation that occurred during the diet reversed in about 7 days.
The study found that maintaining resting and sleeping energy expenditure was important for the drug’s success. Rats on restricted diets showed metabolic adaptation, meaning their bodies burned fewer calories to conserve energy. The drug prevented this adaptation, which contributed to its effectiveness. The respiratory exchange ratio, a measure of what type of fuel the body is burning, converged across all groups by day 42, indicating all rats had reached a similar metabolic state despite different treatments
This research builds on earlier studies showing that appetite-suppressing drugs can be effective for weight loss. The detailed breakdown of how much weight loss comes from eating less versus burning more calories provides new insight. Previous research suggested metabolic adaptation was a major barrier to weight loss, but this study shows that CagriSema can partially prevent this adaptation, which may explain why it works better than diet alone
This study used only male rats, so results may not apply equally to females. Animal studies do not always translate to humans because rats and people have different metabolisms and behaviors. The study did not measure how long the drug’s effects might last with continued use, only what happened during 6 weeks of treatment and 4 weeks after stopping. The exact doses and how they compare to human doses were not detailed in the abstract
The Bottom Line
Based on this research, CagriSema appears to work primarily by reducing appetite rather than increasing calorie burning. If approved for human use, it would likely need to be taken continuously to maintain weight loss, as stopping the drug led to rapid weight regain in rats. This is a moderate confidence finding from animal research that would need human trials to confirm. People considering this drug should understand it is not a one-time treatment but an ongoing medication
This research is most relevant to people with obesity or type 2 diabetes who are considering new treatment options. Healthcare providers developing obesity treatments should pay attention to these findings about how the drug works. People who have struggled with weight loss despite diet and exercise may find this information encouraging, as it suggests a new mechanism for helping with appetite control. However, this is early-stage research in animals, not yet proven in humans
In rats, weight loss occurred rapidly within the first 10 days. Weight stabilized by day 11 and remained stable through day 42 of treatment. After stopping the drug, weight regain began immediately and returned to normal rates within about 4 weeks. If these timelines translate to humans, people might expect to see results within 1 to 2 weeks, but would need to continue taking the drug to maintain those results
Frequently Asked Questions
How does CagriSema help with weight loss compared to just eating less?
CagriSema reduces appetite so people eat less, similar to calorie restriction, but it prevents the metabolic slowdown that normally happens during dieting. In rats, the drug preserved calorie burning while restricted diets alone caused metabolic adaptation.
What happens if you stop taking CagriSema?
Rats regained weight rapidly after stopping the drug, returning to normal weight gain rates within 4 weeks. This suggests the drug requires ongoing use to maintain weight loss, not a one-time treatment.
Does CagriSema work by making your body burn more calories?
No. In rats, only 14% of weight loss came from increased calorie burning. The drug’s main effect was reducing appetite and food intake, which accounted for 86% of the weight loss.
How quickly does CagriSema cause weight loss in the study?
Rats showed rapid weight loss within the first 10 days of treatment. Weight then stabilized from day 11 onward, suggesting an initial fast phase followed by steady maintenance of the lower weight.
Can CagriSema results in rats predict what will happen in humans?
Animal studies provide important clues but do not guarantee human results. Rats and humans have different metabolisms and behaviors. Human clinical trials would be needed to confirm whether these findings apply to people.
Want to Apply This Research?
- Track daily food intake in grams or portions and weekly body weight. This helps identify whether appetite reduction is the primary mechanism of any weight loss medication you take, similar to what researchers measured in this study
- If prescribed a similar medication, log your hunger levels before meals on a scale of 1 to 10 daily. This creates a personal record of how the drug affects your appetite, helping you and your doctor understand whether it is working as intended
- Establish a baseline of your typical food intake and weight before starting any new medication. Continue tracking weekly weight and daily hunger levels for at least 6 weeks to see if the pattern matches the study findings: rapid initial weight loss followed by stabilization. If you stop the medication, continue tracking to monitor whether weight regain occurs as the research predicts
This article summarizes animal research on an experimental drug still in development. CagriSema has not been approved for human use. Results in rats do not guarantee the same effects in humans. Anyone considering obesity or diabetes treatment should consult with a healthcare provider about proven options. This information is for educational purposes only and should not replace professional medical advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.