CagriSema and Muscle Loss: What the 2026 Evidence Actually Shows

Updated: October 27, 2026  |  Evidence review: REDEFINE 1, Novo Nordisk disclosures, and current obesity-treatment guidance

CagriSema has attracted attention for the amount of weight people lost in the phase 3 REDEFINE 1 trial. A more clinically important question is whether that weight loss also preserves muscle, strength and physical function.

The evidence supports a measured conclusion: CagriSema produced substantial fat loss, but the published body-composition results do not establish that it eliminates muscle loss or preserves skeletal muscle better than semaglutide or tirzepatide. The distinction matters because fat mass, lean soft tissue, skeletal muscle and muscle function are related but not interchangeable outcomes.

What readers should know

• In REDEFINE 1, mean weight loss at week 68 was 20.4% using the treatment-policy estimand and 22.7% using the trial-product estimand.
• A small DXA subgroup analysis attributed approximately 67% of weight lost to fat mass and 33% to lean soft tissue.
• That body-composition result is not proof of muscle preservation: DXA lean soft tissue is not a direct measure of skeletal muscle strength or function.
• As of October 27, 2026, CagriSema remains investigational in the United States; Novo Nordisk says an FDA decision is expected in Q4 2026.
• Progressive resistance exercise, adequate individualized nutrition and monitoring of strength and function remain important during substantial weight loss.

What is CagriSema?

CagriSema is an investigational, once-weekly injectable fixed-dose combination of cagrilintide, a long-acting amylin analogue, and semaglutide, a glucagon-like peptide-1 (GLP-1) receptor agonist. The two components act on different but overlapping pathways involved in appetite, satiety and food intake. The combination is being studied for weight management and type 2 diabetes.

CagriSema should not be confused with a medicine that has already been approved for routine obesity treatment. Novo Nordisk submitted a US New Drug Application in December 2025. Its latest public update says an FDA decision is expected in the fourth quarter of 2026. Regulatory status can differ by country, so readers should check the relevant regulator for local status. Novo Nordisk’s FDA filing announcement

What did REDEFINE 1 actually show?

REDEFINE 1 was a 68-week, phase 3, randomized, double-blind trial involving 3,417 adults with obesity, or overweight with at least one weight-related complication, who did not have diabetes. Participants received CagriSema, semaglutide, cagrilintide or placebo alongside lifestyle intervention. The main findings were published in the New England Journal of Medicine in June 2025. Read the published REDEFINE 1 trial

20.4%

Mean weight loss with CagriSema under the treatment-policy estimand, which accounts for outcomes regardless of whether participants remained on treatment.

22.7%

Mean weight loss under the trial-product estimand, an estimate of the treatment effect if participants remained on assigned treatment and did not use other weight-loss therapies.

68 weeks

The randomized treatment period. These figures describe average body-weight change, not the amount of muscle preserved by an individual.

The estimand matters. Treatment-policy estimates are closer to the effect observed when treatment discontinuation and other post-randomization events are included. Trial-product estimates address a more idealized scenario in which participants stay on assigned treatment. Neither should be described as the other.

The published primary-trial and regulatory materials report 20.4% and 22.7% for these two analyses. A percentage quoted elsewhere should be used only when its underlying population, analysis and estimand are clearly identified. The 22.7% estimate should not be presented as though it describes every participant’s expected result.

In REDEFINE 1, the treatment-policy estimates for the individual comparison groups were 14.9% for semaglutide, 11.5% for cagrilintide and 3.0% for placebo. Under the trial-product estimand, the corresponding figures were 16.1%, 11.8% and 2.3%. These figures are useful for understanding trial results, but they do not answer the separate question of which treatment best preserves muscle. American Diabetes Association trial summary

What did the body-composition analysis show?

A DXA (dual-energy X-ray absorptiometry) substudy examined changes in fat mass and lean soft tissue. In Novo Nordisk’s published conference materials, the analysis included 154 participants in the CagriSema group and 55 in the placebo group. The figures below are from the trial-product estimand and were reported by the sponsor. View the REDEFINE 1 scientific presentation

−35.7%

Total body fat mass

Relative change from baseline in the CagriSema DXA subgroup.

−14.4%

Lean soft-tissue mass

Relative change from baseline in the same CagriSema subgroup.

67% / 33%

Composition of weight lost

Approximately 67% was attributed to fat mass and 33% to lean soft tissue in the reported analysis.

These findings show that fat mass fell substantially and that the proportion of body weight represented by lean tissue increased as overall weight declined. They do not show that lean soft tissue was unchanged: the reported analysis also found an absolute reduction in lean soft-tissue mass.

The sample was much smaller than the overall phase 3 trial, and the reported body-composition comparison was not a definitive head-to-head demonstration that CagriSema preserves more skeletal muscle than semaglutide or tirzepatide. The sponsor’s presentation is informative, but it should not be given the same evidentiary weight as a fully published, adequately powered comparative trial of muscle outcomes.

Does CagriSema preserve muscle?

That has not yet been established. The current evidence supports the narrower statement that CagriSema produced substantial fat loss and favorable changes in body composition in a DXA subgroup. It does not justify saying the drug “held” muscle, prevented muscle loss or proved superior muscle preservation to other incretin-based medicines.

There are several reasons for this distinction:

1. Lean soft tissue is not the same as skeletal muscle.

DXA estimates body compartments. Lean soft tissue includes skeletal muscle, but also includes water, organs and other non-fat soft tissues. A change in this compartment cannot be interpreted as a precise measurement of contractile muscle tissue.

2. Relative preservation does not mean no absolute loss.

When fat mass falls more quickly than lean tissue, lean tissue can make up a larger share of the body even while the absolute amount of lean tissue declines. A higher percentage of lean mass after treatment is not, by itself, proof that muscle was maintained.

3. Muscle quantity and muscle function are different outcomes.

A clinically meaningful muscle-preservation claim should also examine strength and function—for example, handgrip strength, chair-rise performance, walking tests and changes in physical capability. A DXA result alone cannot establish those outcomes.

4. The key comparator is missing.

To show that CagriSema is better at preserving muscle, a study needs an appropriate comparison group and standardized measurements. Comparing a subgroup from one trial with published figures from different trials or an unrelated real-world cohort cannot establish superiority.

Why the amylin mechanism is interesting—but not proof

Cagrilintide acts on amylin-related pathways involved in satiety, while semaglutide activates the GLP-1 receptor. Combining them may produce greater appetite suppression and weight loss than either component alone. That biological rationale is credible and consistent with the weight-loss results in REDEFINE 1.

However, a plausible mechanism is not the same as demonstrated muscle protection. To claim that amylin signaling directly protects skeletal muscle, prevents adaptive thermogenesis or reduces future weight regain, researchers would need human data measuring those outcomes. The body-composition findings do not, by themselves, prove those mechanisms.

It is also important not to frame lean-tissue changes as a unique problem caused by GLP-1 medicines. With substantial weight loss from many causes, the body can lose a combination of fat and lean tissue. The proportion depends on factors such as the rate and total amount of weight lost, baseline muscle mass, nutritional intake, age, illness and physical activity.

What the latest 2026 CagriSema updates do—and do not—tell us

Newer disclosures add information about weight loss, but should not be treated as new proof of muscle preservation.

September 2026: REDEFINE 9

Novo Nordisk reported that the lower-dose CagriSema 1.0 mg/1.0 mg regimen reduced body weight by 21.0% at week 68, compared with 2.0% with placebo, in adults with overweight or obesity. This was a topline weight-loss result; the announcement did not establish a muscle-preservation advantage. Read the September 2026 announcement

September 2026: REIMAGINE 5

In adults with type 2 diabetes, CagriSema 1.0 mg/1.0 mg produced 12.4% estimated average weight loss at week 60 versus 9.1% with tirzepatide 5 mg. The populations, doses and trial context matter: this is not a head-to-head comparison against maximum-dose tirzepatide in people without diabetes, and it does not establish comparative effects on muscle. Review the trial details

October 2026: post-hoc analyses in women

Novo reported average weight loss of 25.0% at week 68 among women in a post-hoc REDEFINE 1 analysis, using the efficacy estimand, and further results by menopausal stage. These findings concern weight and waist circumference, not a demonstrated muscle-preservation effect. Because the analyses were post hoc, they should be interpreted as supportive and hypothesis-generating rather than definitive evidence for all patient groups. Read the October 20, 2026 update

Can CagriSema be called better than tirzepatide for muscle?

No. There is not enough direct comparative evidence to support that conclusion. The overall weight-loss estimates reported for CagriSema and tirzepatide come from different trials with different participants, protocols, durations and statistical estimands. A numerical difference between separate studies is not a randomized head-to-head result.

Even if one treatment produces greater average weight loss, that would not automatically mean it preserves more muscle. A proper comparison would need standardized body-composition measurement, information about resistance exercise and nutritional intake, and assessments of strength and physical function. Until such data are available, the fairest conclusion is that CagriSema has promising weight-loss efficacy, while its comparative muscle-preservation profile remains uncertain.

How to reduce the risk of muscle loss during substantial weight reduction

These strategies are relevant to people using approved obesity medicines and to people losing weight through other approaches. They are supportive-care principles, not evidence that CagriSema has a specific muscle-protective effect.

1. Include progressive resistance exercise

Resistance training provides a direct stimulus to maintain strength and muscle. The programme should suit the person’s abilities, health conditions, pain, balance and training history. People who are frail, have significant mobility limitations or are new to exercise may benefit from supervision by a qualified professional.

2. Meet protein and overall nutrition needs

Appetite suppression and gastrointestinal side effects can make it difficult to eat enough. Prioritize protein-containing foods and a nutritionally adequate eating pattern. The appropriate protein target depends on body size, age, kidney function, total energy intake and clinical context; very high targets should not be prescribed universally. A registered dietitian can help tailor intake, especially for people with chronic kidney disease or other conditions affecting diet.

3. Monitor function as well as weight

The scale does not show whether strength is improving or declining. Depending on the person’s needs, a clinician may track strength, sit-to-stand performance, walking ability, falls, nutritional intake and physical activity. DXA or bioelectrical impedance may be useful in selected cases, but results depend on the method and should be interpreted in context.

4. Address side effects that undermine intake

Persistent nausea, vomiting, constipation or difficulty eating can interfere with hydration and adequate nutrition. Discuss ongoing or severe symptoms with the prescribing clinician rather than simply tolerating them. Do not change a prescribed treatment schedule without medical advice.

5. Individualize the plan for people at higher risk

Older adults, people with low baseline muscle mass, frailty, prior falls, chronic illness or a history of malnutrition may need closer monitoring and a tailored nutrition and exercise plan during weight reduction.

Current obesity-treatment guidance emphasizes adequate nutritional intake, sufficient protein and muscle-strengthening activity during pharmacologic weight management. These principles are supported by broader evidence on weight loss and muscle health—not by a claim that one investigational drug eliminates lean-tissue loss. Expert consensus on nutritional and lifestyle support during GLP-1-based treatment | Pharmacologic Treatment of Obesity in Adults: Standards of Care

What evidence would prove a muscle-preserving advantage?

A convincing claim would require more than a favorable percentage of fat loss. Ideally, researchers would conduct a prespecified randomized comparison with:

• Standardized measurements of fat mass and lean tissue, with clear definitions of each outcome.
• More direct estimates of skeletal muscle quantity where feasible, alongside body-composition measurements.
• Validated measures of muscle strength and physical performance, such as handgrip strength, chair-rise testing or walking assessments.
• Documented exercise, protein intake, treatment adherence and relevant baseline risk factors.
• Enough participants and follow-up to evaluate whether any differences are clinically meaningful and durable.

Longer follow-up would also help determine whether any differences persist after the initial weight-loss period. Until this evidence is available, the phrase “muscle-sparing CagriSema” should be treated as a hypothesis, not a proven clinical outcome.

Safety and regulatory status

CagriSema is investigational and should not be used as though it were an approved, commercially available obesity medicine in the United States. The pivotal REDEFINE 1 trial reported gastrointestinal adverse events, including nausea, constipation and vomiting. Novo Nordisk’s regulatory summary reported that adverse-event-related treatment discontinuation in REDEFINE 1 was 5.9% with CagriSema and 3.5% with placebo. Individual risks and suitability require clinical assessment. Trial safety and regulatory summary

As of October 27, 2026, Novo Nordisk states that the FDA decision on its weight-management application is expected in Q4 2026. Approval should not be assumed before the regulator announces a decision. The status described here is time-sensitive and should be rechecked before publication updates or clinical decisions.

Frequently asked questions

Does CagriSema prevent muscle loss?

No. Available body-composition data show substantial fat loss alongside a reduction in lean soft-tissue mass. They do not establish that CagriSema prevents muscle loss or preserves muscle better than other treatments.

What percentage of weight lost with CagriSema was lean tissue?

In the sponsor-reported DXA subgroup, approximately 33% of weight lost was attributed to lean soft tissue and 67% to fat mass. These are subgroup estimates and should not be interpreted as an exact prediction for every individual.

Is lean soft tissue the same as muscle?

No. Lean soft tissue includes skeletal muscle as well as water, organs and other non-fat soft tissues. DXA estimates body compartments; it does not directly measure muscle strength or physical function.

Is CagriSema proven to preserve more muscle than tirzepatide or semaglutide?

No. A definitive head-to-head comparison of muscle quantity and function has not been established by the cited evidence. Comparing body-weight results from separate clinical trials cannot answer that question.

Is CagriSema approved by the FDA?

As of October 27, 2026, Novo Nordisk describes CagriSema as investigational and says an FDA decision is expected in Q4 2026. Check the FDA and local regulator for the latest status.

What is the best way to protect muscle during weight loss?

Evidence-based supportive care includes individualized adequate nutrition, sufficient protein for the person’s needs, progressive resistance exercise and monitoring of strength and function. People with kidney disease, frailty, nutritional problems or other complex health conditions should seek individualized clinical advice.

Conclusion

CagriSema’s REDEFINE 1 results are important for obesity treatment, and its DXA substudy indicates that most of the weight lost was fat mass. But approximately one-third of weight loss in that analysis was attributed to lean soft tissue, which declined in absolute terms. The evidence therefore does not justify claiming that CagriSema “held the muscle” or has proven muscle-sparing superiority.

The next phase of research should measure more than the number on the scale: it should assess skeletal muscle, strength, function, nutritional status and long-term outcomes. For now, the defensible clinical message is straightforward—substantial weight loss can improve body composition while still reducing lean tissue, and muscle-supportive nutrition, resistance exercise and appropriate monitoring remain important whatever treatment is used.

Sources and further reading

1. Garvey WT, et al. Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. 2025;393:635–647. doi:10.1056/NEJMoa2502081
2. American Diabetes Association. CagriSema Demonstrates Significant Weight Loss in Adults with Obesity. June 22, 2025. Trial summary
3. Novo Nordisk. REDEFINE 1 scientific presentation, including DXA body-composition data. American Diabetes Association Scientific Sessions, June 2025. Conference presentation PDF
4. Novo Nordisk. CagriSema FDA New Drug Application submission and REDEFINE 1 results. December 18, 2025. Regulatory announcement
5. Novo Nordisk. REDEFINE 9 and REIMAGINE 5 topline results. September 21, 2026. Company announcement
6. Novo Nordisk. Post-hoc REDEFINE 1 analyses in women and by menopausal stage. October 20, 2026. Company announcement
7. Nutritional and lifestyle supportive care recommendations for management of obesity with GLP-1-based therapies: expert consensus statement. Full text
8. American Diabetes Association. Pharmacologic Treatment of Obesity in Adults: Standards of Care in Overweight and Obesity. Guidance

Medical disclaimer: This article is for educational purposes and is not medical advice. It does not recommend starting, stopping or changing a prescription medicine. CagriSema’s regulatory status may change; consult the relevant regulator and a qualified healthcare professional for current, individualized advice.