What Randomised Controlled Trials of Anti-Obesity Medications Tell us About Lifestyle Interventions

Over the past several years we have seen a spate of large randomised controlled trials (RCTs) designed to test the efficacy of various anti-obesity medications. All of these trials included a control group, in which patients were offered some form of dietary counseling aimed at reducing caloric intake and instructions on increasing physical activity.

Perhaps, even more importantly, these studies were conducted in volunteers, run at centres with at least some expertise in obesity management, and included regular visits and contact with study personnel, all factors that would be expected to promote weight loss. 

Taken together, most of these features would by far exceed what would normally be offered in terms of obesity management in routine clinical practice. 

Thus, it would be fair to say that the control groups in these studies are not only a reflection of what may be expected in ‘usual care’ with lifestyle interventions but most likely represent best outcomes. 

Although I have not conducted a formal meta-analysis of these trials, it is quite evident that the average weight loss in the control groups ranges somewhere between 3-6% of initial weight. 

This, interestingly enough, is exactly the range of weight loss seen in RCTs that are specifically designed to test various dietary and other non-pharmacological treatments for obesity. 

In light of these findings, it would only be fair to conclude that based on the vast body of evidence from RCTs on various obesity treatments – the best we can expect in terms of weight loss from behavioural interventions (even in volunteers, seen at regular intervals by experts in the field), is in the ball-park of 3-6%.

While this degree of weight loss may well have some health benefits, these outcomes should be rather sobering, to anyone who believes that they can “conquer” their obesity with “lifestyle-change”.

In practical terms, if all you are aiming for is a 3-6% weight loss, it would be fine to just see a dietitian and perhaps increase your physical activity – for anything more, you should clearly be looking at adding medication or perhaps considering surgery (where indicated).

Berlin, D