According to research reviewed by Gram, the FIT-HF trial will test whether semaglutide improves exercise capacity more than an intensive low-calorie diet in 100 adults with obesity and heart failure with reduced ejection fraction. The trial has not reported results yet, so no conclusion about which approach works better can be drawn at this time.
Obesity is common in people with a weakened heart pump, and doctors are unsure whether losing weight helps or harms them. According to research reviewed by Gram, a new trial called FIT-HF will compare two weight-loss approaches: a once-weekly injection called semaglutide and a short, very low-calorie liquid diet. The study plans to enroll 100 adults with obesity and heart failure with reduced ejection fraction, a condition where the heart pumps less blood than normal. The main question is which approach better improves how far and how hard people can exercise after one year. This article describes the study design and plan. The trial has not yet reported results, so no conclusions about which approach works best can be drawn yet.
Key Statistics
A 2026 randomized controlled trial protocol published in Clinical Nutrition ESPEN plans to enroll 100 adults with obesity and heart failure with reduced ejection fraction to compare semaglutide with a diet of about 800 calories per day.
The FIT-HF trial will follow participants for 52 weeks and measure change in peak oxygen uptake, a standard test of exercise capacity, as its primary outcome.
The planned semaglutide arm will increase the weekly injection dose gradually to a target of 2.4 mg, while the diet arm will follow an approximately 800-calorie-per-day plan for 8 weeks.
The Quick Take
- What they studied: Researchers want to know whether a weight-loss injection called semaglutide helps people with heart failure exercise better than an intensive low-calorie diet.
- Who participated: The study plans to enroll 100 adults who have obesity and a weakened heart pump (heart failure with reduced ejection fraction). Their symptoms must be stable and they must already be taking standard heart failure medicines. Participants have not yet been reported on, because the trial is still in its planning and enrollment stage.
- Key finding: No findings are available yet. This paper is a protocol, which is a detailed plan published before a study begins, so it describes how the trial will be run rather than what it found. The main measure will be peak oxygen uptake, a standard test of how efficiently the body uses oxygen during hard exercise.
- What it means for you: No changes to your treatment should be based on this paper alone. If you have heart failure and obesity, talk with your cardiologist about weight management options that are right for you. Future results may help clarify which approach works best for people in your situation.
The Research Details
FIT-HF is a randomized controlled trial, a type of study where participants are assigned to different treatments by chance. This method helps make the two groups as similar as possible at the start, so any differences seen later are more likely to come from the treatment itself. Participants will be split evenly into two groups. One group will receive weekly semaglutide injections, with the dose gradually increased to a target of 2.4 mg. The other group will follow a low-calorie diet of about 800 calories per day, replacing regular meals, for 8 weeks. After that, they will move to a dietitian-guided plan to keep the weight off.
Both groups will receive lifestyle advice, standard heart failure care, and a structured exercise program starting at week 16. The study is open-label, which means participants and their care teams know which treatment they are receiving. However, the people who measure outcomes, called assessors, will not know which group each participant is in. This helps reduce bias in how results are scored. Follow-up will last 52 weeks, which allows researchers to see whether benefits last beyond the early months of weight loss.
The trial will measure several outcomes using standard tests. The main outcome is peak oxygen uptake, measured during a cardiopulmonary exercise test on a treadmill or bicycle while breathing is monitored. Other measures include a quality-of-life questionnaire for heart patients, a 6-minute walk test, heart imaging, and blood tests for inflammation and heart stress markers.
Comparing a medicine with a strong diet plan is useful because most people with obesity and heart failure would choose between these options in real life. A direct head-to-head comparison can show which approach provides more benefit, rather than only showing whether each one works on its own. Measuring exercise capacity alongside weight loss and body composition also helps explain whether improvements come from the weight loss itself or from other changes in the body.
The paper is a protocol, meaning it describes the plan before results exist. Publishing a protocol in advance is good practice because it limits the chance that researchers change their main question after seeing the data. The trial is registered under identifiers in both the European Union and ClinicalTrials.gov, which adds transparency. However, a study of 100 people is relatively small, so results will need to be confirmed in larger studies. Because participants know their treatment, some outcomes that rely on self-reporting could be influenced by expectations, even though assessors are blinded.
What the Results Show
This paper does not report any results yet. The trial’s main goal is to measure the change in peak oxygen uptake, adjusted for body weight, from the start of the study to 52 weeks. Peak oxygen uptake is a common measure of fitness in heart patients, and higher values generally mean the heart and lungs can deliver more oxygen to working muscles. Researchers will compare how much each group improves on this measure.
The study is designed to test whether semaglutide is better than the intensive diet, which is described as superior testing. This means the researchers are looking for a clear advantage for one approach, not just a similar result. Because the trial is still planned, the size of any difference, and whether it will be meaningful for patients, remains unknown.
The researchers have also planned to track how much weight each person loses and changes in body composition. These details will help explain whether any exercise improvement is linked to fat loss, muscle changes, or both. Results have not been released, and conclusions should wait until the trial is complete and published.
The trial plans to measure several secondary outcomes. These include a heart-related quality-of-life questionnaire, a 6-minute walk test, and heart imaging that tracks the size of a key heart chamber at its most contracted point. Blood tests will measure inflammation and a marker of heart strain called N-terminal pro-B-type natriuretic peptide. Together, these measures will show whether any changes in exercise ability also reflect changes in daily life, heart structure, or heart stress.
Safety is also an important focus. Earlier studies of similar medicines in other heart conditions raised questions about safety, so the trial includes exploratory work to monitor side effects, heart and lung function, physical activity, and metabolic changes. No safety findings are available yet.
Medicines in the same drug family as semaglutide have improved symptoms and exercise ability in people with a different type of heart failure, where the heart fills normally but stiffens. Evidence in people with a weakened heart pump, the group studied here, is more limited. Earlier trials of similar drugs in heart patients also raised safety questions, which is one reason researchers want to study this group carefully. The authors describe FIT-HF as the first direct comparison of these two weight-loss strategies in this population, so there is no earlier head-to-head result to compare it with.
Because this is a protocol, there are no results to judge. Several limitations are already clear from the design. The trial includes only 100 participants, which may not be large enough to detect small differences or rare side effects. Because the diet and drug groups look and feel different, participants will know which treatment they receive, which may affect how they report symptoms. The follow-up period of one year is useful but does not show whether benefits last for many years. The study also enrolls adults with stable symptoms, so results may not apply to people who are very sick or who have other health conditions.
The Bottom Line
No treatment recommendation can be made from this protocol alone, because the trial has not reported results. Current clinical care for heart failure and obesity is guided by existing guidelines and the judgment of your care team. Until FIT-HF publishes results, decisions about semaglutide or low-calorie diets should be made with a doctor who knows your full medical history. Confidence in any future conclusion will depend on the size and quality of the final results.
People with obesity and heart failure with reduced ejection fraction, along with their cardiologists, dietitians, and weight-management teams, may find the eventual results useful. Researchers and clinicians interested in how weight loss affects heart function will also benefit. People without heart failure, or those who do not have obesity, are not the population studied, so these findings would not directly apply to them.
The trial follows participants for 52 weeks, so any results on the main outcome will not be available until at least one year after enrollment begins. Publication of final findings usually takes additional months after data collection ends. Anyone considering these approaches should expect that research results will take well over a year to appear, and that treatment decisions should still rely on current medical guidance.
Frequently Asked Questions
Does semaglutide work better than diet for heart failure patients with obesity?
The FIT-HF trial is designed to answer this question, but results have not been published yet. It will compare semaglutide with an 800-calorie-per-day diet in 100 adults over 52 weeks, using exercise capacity as the main measure.
What is the FIT-HF trial studying?
The FIT-HF trial studies whether weight loss through semaglutide injections or a low-calorie diet improves exercise ability in adults with obesity and heart failure with reduced ejection fraction. It is a randomized study with 100 planned participants and one year of follow-up.
How long will the FIT-HF trial last?
Each participant in the FIT-HF trial will be followed for 52 weeks. The diet group completes an intensive 8-week phase, then moves to a weight-maintenance plan, while the semaglutide group titrates up to a target dose of 2.4 mg weekly.
Is it safe for people with heart failure to use semaglutide for weight loss?
Safety is being tracked in the FIT-HF trial, but no safety results are available yet. Earlier trials of similar medicines in other heart conditions raised safety questions, so people with heart failure should discuss semaglutide with their cardiologist before considering it.
Want to Apply This Research?
- Track your weekly body weight, using the same scale and time of day, and log your walking distance over six minutes if your care team has shown you how to do this safely. Record how many days per week you complete at least 20 minutes of activity. Share these numbers with your doctor, since they can help show progress over time.
- Set a small, realistic goal for a daily walk and increase it gradually as your care team approves. Pair this with regular meal planning, such as filling half your plate with vegetables. If you are considering any new weight-loss approach, use the app to write down questions for your next appointment instead of making changes on your own.
- Review your logs monthly to spot trends in weight, activity, and energy levels rather than focusing on single days. Note any symptoms such as shortness of breath, swelling, or dizziness, and report them to your care team promptly. Check back for updates on the FIT-HF trial results, and bring any new findings to your doctor for a personal discussion.
This article describes a research protocol for a clinical trial that has not yet reported results. It is for general information only and does not replace medical advice. Semaglutide is a prescription medicine with possible side effects, and it is not appropriate for everyone. People with heart failure should never start, stop, or change medicines or diets without consulting their doctor or cardiologist first.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.