New Weight Loss Study: GLP-1 Drugs Combined with Behavioral Therapy Achieve 25% Body Weight Reduction
Quick Facts
What Do Clinical Trials Show About GLP-1 Drugs and Behavioral Therapy?
The STEP program is a series of large randomized controlled trials evaluating semaglutide 2.4mg for weight management. The STEP 3 trial (Wadden et al., JAMA 2021) specifically tested semaglutide combined with intensive behavioral therapy in 611 adults with overweight or obesity. Participants receiving semaglutide plus IBT lost approximately 16% of body weight at 68 weeks, compared to 5.7% in those receiving IBT plus placebo.
In the separate STEP 1 trial (Wilding et al., NEJM 2021), semaglutide 2.4mg alone — without intensive behavioral therapy — achieved 14.9% weight loss at 68 weeks in 1,961 participants, with approximately 32% of participants losing 20% or more of body weight. Comparing across these trials suggests that adding structured behavioral support to GLP-1 medication enhances outcomes, and researchers are actively investigating more comprehensive combination programs that may achieve even greater results.
What Does the Behavioral Therapy Program Include?
The intensive behavioral therapy used in the STEP 3 trial was based on the Diabetes Prevention Program (DPP) lifestyle intervention, which has strong evidence for producing sustained weight loss. Key components included:
Participants attended 30 counseling sessions over the 68-week trial period, covering topics such as identifying eating triggers, managing emotional eating, stress management, and building sustainable habits. They followed reduced-calorie meal plans (approximately 1,200–1,800 kcal/day depending on baseline weight) with guidance on food selection and portion control. A supervised exercise program encouraged participants to gradually increase physical activity to at least 200 minutes per week, combining aerobic and resistance training. The DPP model on which this was based demonstrated approximately 7% weight loss and a 58% reduction in diabetes risk in its original trial.
Why Does the Combination Work Better Than Either Treatment Alone?
Semaglutide works primarily by mimicking the hormone GLP-1, which reduces appetite, slows gastric emptying, and alters food reward signaling in the brain. This biological effect reduces hunger and cravings, making it easier for patients to eat less. However, the drug alone does not directly change food selection quality, eating patterns, or exercise behavior.
Behavioral therapy addresses these psychological and behavioral factors: teaching patients to choose nutrient-dense foods, establish regular meal timing, manage emotional eating, and build consistent exercise habits. When combined, the reduced appetite from medication makes it easier to follow behavioral changes, while the improved eating patterns and exercise may maximize the metabolic benefits of the medication. Evidence from the STEP trials supports this complementary approach, and researchers believe more intensive combination programs could push weight loss outcomes significantly beyond what either treatment achieves alone.
What Happens After Stopping GLP-1 Medication?
One of the most important concerns with GLP-1 medications is weight regain after stopping treatment. The STEP 4 trial (Rubino et al., JAMA 2021) directly addressed this question. After 20 weeks of semaglutide treatment (during which participants lost approximately 10.6% of body weight), those switched to placebo regained about two-thirds of the lost weight over the following 48 weeks, while those who continued semaglutide lost additional weight.
This significant rebound effect has become one of the biggest criticisms of GLP-1 drugs for obesity. Researchers hypothesize that patients who develop strong behavioral habits through intensive therapy may be better equipped to maintain weight loss after discontinuing medication, since they have tools for managing appetite and food choices that are independent of the drug's biological effects. While long-term data on combination therapy discontinuation is still being gathered, the rationale for pairing medication with behavioral skills training is strongly supported by this weight regain challenge.
Frequently Asked Questions
In the STEP 3 clinical trial, participants receiving semaglutide 2.4mg combined with intensive behavioral therapy lost approximately 16% of body weight at 68 weeks. For someone weighing 110 kg (242 lbs), this would be roughly 17.6 kg (39 lbs). Researchers are studying more intensive combination programs that may achieve even greater weight loss.
While GLP-1 drugs are effective on their own (approximately 15% weight loss in STEP 1), adding behavioral therapy has been shown to improve outcomes in clinical trials. Critically, behavioral skills may also help with long-term weight maintenance after stopping medication, since the STEP 4 trial showed significant weight regain when semaglutide was discontinued without behavioral support.
It typically includes structured counseling sessions targeting eating behaviors, personalized meal plans with calorie targets, supervised exercise programs, and individual or group support. The model used in clinical trials is based on the Diabetes Prevention Program, which has decades of evidence supporting its effectiveness for weight management.
Research suggests significant weight regain is common after stopping GLP-1 medications. The STEP 4 trial showed participants regained approximately two-thirds of their prior weight loss within about a year of switching from semaglutide to placebo. This is why many experts recommend combining medication with behavioral therapy to build lasting habits that support weight maintenance.
Coverage varies by insurer and state. Medicare covers intensive behavioral counseling for obesity in primary care settings. Many commercial insurers now cover behavioral therapy when prescribed alongside anti-obesity medications, though prior authorization may be required. Check with your insurance provider for specific coverage details.
References
- Wadden TA, et al. Effect of subcutaneous semaglutide vs placebo as an adjunct to intensive behavioral therapy on body weight in adults with overweight or obesity: the STEP 3 randomized clinical trial. JAMA. 2021;325(14):1403-1413.
- Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). New England Journal of Medicine. 2021;384(11):989-1002.
- Rubino D, et al. Effect of continued weekly subcutaneous semaglutide vs placebo on weight loss maintenance in adults with overweight or obesity (STEP 4). JAMA. 2021;325(14):1414-1425.
- Diabetes Prevention Program Research Group. Long-term effects of lifestyle intervention or metformin on diabetes development and microvascular complications. The Lancet Diabetes & Endocrinology. 2015;3(11):866-875.
- Garvey WT, et al. American Association of Clinical Endocrinology and American College of Endocrinology comprehensive clinical practice guidelines for medical care of patients with obesity. Endocrine Practice. 2016;22(Suppl 3):1-203.