Weight Loss Research 2025

Weight Loss Research 2025

A recent trial (called STEP-UP) looked at raising the dose of semaglutide (Wegovy/Ozempic) from around 2.4 mg to 7.2 mg weekly. Over ~72 weeks, people on the higher dose lost an average of ~19% of their body weight, compared to ~16% on the standard dose and ~4% on the placebo.

New Drugs & Combinations with Strong Results

Amycretin: In a proof-of-concept trial, this new agent (a GLP-1 + amylin receptor agonist by Novo Nordisk) at 20 mg achieved ~22% weight loss at 36 weeks in overweight/obese adults. Safety was comparable to that of existing incretin-based therapies.

Tufts’ “Retatrudide”: A multi-hormone agonist designed to include additional hormonal pathways (e.g., PYY along with GLP-1, etc.), aiming for higher loss (~24%) with fewer side effects. Early but promising.

MariTide (Amgen): Another newer therapy; in phase 2 trials, it gave 12-16% weight loss over a year in people without type-2 diabetes; somewhat lower but still meaningful in those with T2D.

Diet Gives Benefits Beyond Just Weight Loss

One study from Harvard and Ben Gurion University shows that even people who didn’t lose weight after switching to a healthier diet still got benefits: better HDL cholesterol, lower visceral fat, and reduced leptin. Meaning: health gains don’t always require big drops in scale weight.

Early Medication Helps Non-Responders to Behavioural Programs

A study showed that among people who didn’t respond (i.e. <2% weight loss) after a month of behavioural intervention, adding phentermine (an older appetite suppressant) doubled their weight loss over the next 24 weeks versus continuing behaviour alone.

Muscle Preservation During Weight Loss Gets Attention

Some of the newer studies are not just tracking how much weight people lose, but what kind of weight: fat vs. muscle. In particular, a study (BELIEVE) combined semaglutide with bimagrumab and other strategies to try to preserve lean mass. This matters for long-term health (strength, metabolism).

Shifts in Treatment Patterns

Pediatric obesity treatment is changing: Since the American Academy of Paediatrics (AAP) released comprehensive guidelines in 2023, use of anti-obesity medications among children/adolescents has increased, especially among adolescents. Lifestyle interventions remain first line, but medications are being used more often.

Cost-Effectiveness and Policy Implications

An Institute for Clinical and Economic Review (ICER) report finds GLP-1 drugs becoming more cost-effective than in past years, due both to better evidence (e.g. cardiovascular benefits) and slight price declines. But still, high cost remains a big barrier.

A policy/economics analysis (by ITIF) argues that broader access to GLP-1s could deliver societal benefits: reduced healthcare costs, better productivity, etc. But hurdles around insurance, long-term safety, and equity remain.

Limits, Challenges, and Unknowns

Side Effects & Tolerance: Higher doses often bring more GI issues (nausea, etc.), and not everyone tolerates them well.

Real-World vs Clinical Trials: Outcomes in actual practice tend to be lower than in tightly controlled clinical trials. Medication adherence, lifestyle support, and patient selection matter a lot.

Long-Term Sustainability: What happens if people stop these drugs? Weight regain is common, and very few studies yet extend beyond 1-2 years in real-world settings. Also, long-term effects on bones, muscles, and organs are still under study.

Access & Equity: Cost, insurance coverage, and disparities (geographic, socioeconomic) limit who benefits. Medications remain expensive, and many areas lack providers who manage obesity as a medical disease.

Stigma & Social Perception: As new weight-loss medications become widespread, there are both potential positive and negative impacts on how obesity is viewed socially, personally, and in terms of stigma. A narrative review in Current Obesity Reports is exploring this.

Where Things Are Likely to Go Next

Drugs that combine or target multiple hormonal pathways (beyond just GLP-1) seem to be a major focus (e.g., dual or triple agonists). The goal is to get closer to the weight-loss magnitudes seen in bariatric surgery, but with fewer risks.

Oral formulations and less frequent dosing (monthly, etc.) are being tested and may help with adherence.

More emphasis on preserving lean body mass rather than just weight, better tools (biosensors, imaging) to track fat vs muscle.

Earlier intervention: using meds sooner for people not responding to lifestyle, using in adolescents, etc.

Broader systemic / policy changes: ensuring cost coverage, integrating obesity treatment in primary care, better guidelines, perhaps regulation on food environment, etc.

Bottom Line

Recent U.S. studies in 2025 are pushing the science of weight loss past traditional diet/exercise models toward more nuanced drug treatments, better quality of loss (fat vs muscle), and healthier biomarkers ,even when weight loss is modest. The tradeoffs still include cost, side effects, and questions about long-term stability. For many, combining newer medications with good behavioural and lifestyle support is looking like the strongest strategy.