Diet and exercise with vs without weight-loss medication: what the evidence shows
What two clinical trials found when medication was added to lifestyle support, and why ongoing care still matters.
Food, movement and clinical treatment can each have a place in weight care. Medication may help some people alongside lifestyle support, but suitability, side effects and follow-up matter as much as a headline result.
What did the trials compare?
STEP 1 and SURMOUNT-1 studied adults with obesity, or overweight with a weight-related condition, who did not have diabetes. In each trial, participants received either the study medicine or a placebo, alongside lifestyle intervention.
These were comparisons within specific research programmes. Their placebo results do not describe what every person can achieve through diet and exercise, and the two trials were not a direct comparison of the medicines.
| Trial and duration | Treatment alongside lifestyle intervention | Average body weight change | Reached at least 5% weight loss |
|---|---|---|---|
| STEP 1, 68 weeks | Placebo | −2.4% | 31.5% |
| STEP 1, 68 weeks | Semaglutide 2.4 mg | −14.9% | 86.4% |
| SURMOUNT-1, 72 weeks | Placebo | −3.1% | 35% |
| SURMOUNT-1, 72 weeks | Tirzepatide 10 mg | −19.5% | 89% |
| SURMOUNT-1, 72 weeks | Tirzepatide 15 mg | −20.9% | 91% |
These are the primary trial reports' treatment-policy or treatment-regimen estimates, which account for treatment discontinuation. Results varied between participants. The figures are not personal forecasts or Bion programme outcomes.
What changes when medication is added?
Some weight-management medicines can reduce hunger or help people feel full sooner. That can make changes to eating more manageable for some people. It does not mean hunger disappears or that everyone responds in the same way.
Medicines also carry risks. Gastrointestinal side effects were common in these trials, and some participants stopped treatment because of adverse effects. A clinician weighs potential benefits against your health history, other medicines and possible harms.
Why keep food and movement in the plan?
Medication does not replace healthy eating or physical activity. Ask your care team how to build meals, activity and strength work around your needs, especially if appetite changes or eating enough becomes difficult.
A useful review looks beyond weight: what you can do, how you feel, your routine and any symptoms you want to discuss. These are reasons to keep a record, rather than chase a particular trial percentage.
What happens if treatment stops?
In an exploratory STEP 1 extension, 327 participants were followed after both medication and the study's lifestyle intervention ended. Over the following year, the semaglutide group regained about two-thirds of its previous weight loss on average.
That finding supports planning for ongoing care. It does not prove that everyone will regain the same amount, or that a particular routine guarantees maintenance. Discuss treatment changes and follow-up with your clinician.
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Sources: STEP 1 primary report, NEJM 2021; SURMOUNT-1 primary report, NEJM 2022; STEP 1 exploratory extension, 2022; NIDDK prescription medications guide. Evidence checked 30 October 2026.