Weight-loss drugs lose edge fast after coverage stops, study shows

People who stop today’s blockbuster weight‑loss drugs typically regain most of the weight – and lose the health gains – in under two years, raising tough questions about how long plans should pay for them. 

According to a new systematic review and meta‑analysis in The BMJ, researchers pooled 37 studies involving 9,341 adults with overweight or obesity who used one of 18 weight management medications for at least eight weeks and then stopped.  

The drugs included semaglutide and tirzepatide, as well as older agents such as orlistat, liraglutide and phentermine combinations. 

The BMJ paper reported three core findings that matter for benefit design: 

1. Weight and risk factors bounce back quickly 

According to The BMJ, across all medications people lost about 8.3 kg during treatment, then regained roughly 0.4 kg a month after stopping. That trajectory put average body weight back at baseline roughly 1.7 years after discontinuation. 

Cardiometabolic markers followed the same pattern.  

The BMJ authors said HbA1c, fasting glucose, blood pressure, total cholesterol and triglycerides improved while patients took the drugs, but modelling suggested they generally returned to pre‑treatment levels within about 1.0–1.4 years of stopping. 

2. Newer incretin drugs are stronger – but not stickier 

As per The BMJ, people on newer incretin mimetics such as semaglutide and tirzepatide lost about 14.7 kg during therapy, more than with other drugs.  

Once they stopped, however, they regained weight at about 0.8 kg a month – roughly double the overall rate. 

Reuters reported that this works out to nearly 1.8 pounds (0.8 kg) regained per month after stopping semaglutide or tirzepatide, with patients returning to baseline weight in about 1.5 years, versus 1.7 years after stopping any weight‑loss medication.  

Reuters quoted senior researcher Dimitrios Koutoukidis of Oxford University as saying that because people on semaglutide or tirzepatide lose more weight in the first place, “they all end up returning to baseline at approximately the same time.” 

3. Behavioural programs look slower but more durable 

The same Oxford group previously reviewed behavioural weight management programmes that focus on diet and physical activity.  

According to The BMJ re‑analysis, participants in these programmes lost around 5.1 kg, then regained about 0.1 kg a month once formal support ended. 

When researchers put the two approaches side by side, The BMJ reported that people on medications lost an additional 3.2 kg on average during treatment compared with behavioural programmes, but regained weight about 0.3 kg a month faster after stopping.  

The models projected a return to baseline weight about 3.9 years after a behavioural programme versus 1.7 years after discontinuing drugs. 

The BMJ authors pointed out that obesity is a chronic, relapsing condition and argued that, in practice, many people may need long‑term or repeated pharmacological treatment to sustain benefits.  

They also noted real‑world data suggesting that about half of patients stop GLP‑1 receptor agonists within a year, which shortens the window of benefit even further. 

Reuters said that the analysis could not identify which patients are more likely to keep the weight off after stopping.  

Reuters quoted Koutoukidis describing that as a “holy grail” question in weight‑loss research that nobody can yet answer. 

For plan sponsors and administrators, the key signals from The BMJ are: 

• These drugs deliver large, clinically meaningful weight and risk‑factor reductions while people are on them. 

• Once coverage or use stops, both weight and cardiometabolic markers tend to drift back toward baseline within roughly one to two years. 

• Behavioural support appears to yield smaller initial losses but slower regain and longer‑lasting benefits after formal intervention ends. 

Those findings support treating obesity more like a chronic condition requiring ongoing management, rather than a short course of therapy, and they underline the value of pairing any drug coverage with sustained behavioural support rather than relying on medications alone.