Supervised exercise started 10 days after bariatric surgery did not increase weight loss in a randomized trial

A randomized trial published on September 5, 2026 in Obesity Surgery tested a 16-week supervised exercise program that started about 10 days after weight-loss surgery. The program did not produce more weight loss than usual care, either at 4 months or at 12 months.

The trial is called EFIBAR. Eighty patients having bariatric surgery at Complejo Hospitalario Torrecárdenas in Almería, Spain were assigned at random to usual care after surgery, or to usual care plus the training program. Random assignment is what makes a comparison like this worth reading. It keeps the two groups similar at the start, so a difference in results is more likely to come from the program than from which patients were the type to exercise anyway.

The program ran three sessions a week, 60 minutes each, with a trainer supervising each person individually. It combined resistance training, meaning weights, at 50 to 75 percent of the heaviest load a person could lift once, and aerobic training at 65 to 85 percent of heart rate reserve, which is a way of setting effort using a person's own resting and maximum heart rates. Patients were measured before surgery and again at 4 and 12 months.

Both groups lost about 37 percent of their body weight by one year

The result the trial was built to answer was percent total weight loss, meaning the share of starting body weight a person lost. At 4 months it was 24.9 percent with exercise and 23.4 percent without. At 12 months it was 37.0 percent with exercise and 37.2 percent without. The researchers reported no statistically significant difference, which means the gaps were small enough to be explained by ordinary chance rather than by the program.

Body composition, inflammation markers measured in blood, and physical fitness testing also showed no significant difference between the groups at any time point. The fitness result is the surprising one, because protecting fitness and muscle is the usual reason exercise is prescribed in the months right after surgery.

Blood pressure and blood sugar improved at four months, then the difference disappeared

Two secondary measurements did favor the exercise group early. At 4 months, systolic blood pressure, which is the upper number and reflects the pressure in the arteries when the heart beats, was 6.5 mmHg lower in the exercise group, with a 95 percent confidence interval running from 0.2 to 12.7 mmHg. Glycated hemoglobin, usually written HbA1c, which reflects average blood sugar over roughly the previous three months, was 0.3 percentage points lower, with an interval of 0.1 to 0.5.

A confidence interval is the range of underlying values the data are compatible with. Both of these ranges stop just short of zero, so the findings clear the usual statistical bar but do not clear it by much. Neither difference was still present at 12 months.

In the paper's key points, the authors describe early supervised exercise as a safe addition to care after surgery. The published abstract does not include a safety table, so that description cannot be checked against numbers here.

Eighty patients at one hospital cannot rule out a smaller benefit

The trial enrolled 80 people at a single hospital. A study that size can detect a large effect on weight loss and would miss a small one. So the fair reading is not that exercise does nothing after bariatric surgery. It is that this program, at this intensity, starting this early, did not add measurable weight loss on top of what the surgery itself produced, and both groups lost a great deal of weight either way.

The trial was registered before it began, under the identifier NCT03497546, with percent total weight loss named in advance as the main outcome. That matters, because it means the negative result was not produced by switching to a different outcome after the numbers came in. The registry lists a single site, 80 participants, a start date of May 2018 and completion in September 2022.

The published abstract does not break the results down by operation type, and the full paper sits behind a paywall. This brief relies on the abstract, the journal's key points, and the trial registry entry.