CBT After Metabolic Surgery: Tell the Story You Like

Often in scientific research we find a tension between answering a question and telling a story. A recent study of cognitive behavioral therapy (CBT) after metabolic surgery offers a case in point. The scientists who designed this study wanted to answer a simple question. Does CBT improve the the clinical outcome of weight reduction? Or not? They got an answer – it does not.

This is the starting point for storytelling. Headlines about this study cover quite a range. Take your pick:

No Weight Benefits With Phone-Based CBT a Year After Bariatric Surgery

or

Cognitive Behavioral Therapy Aids Outcomes One Year After Bariatric Surgery

An RCT of CBT for Weight Loss

The design of the study makes it quite clear. The question that Sanjeev Sockalingam and colleagues sought to answer was straightforward. The primary outcome measure reflected this. It was change in weight, measured in kilograms. Nine other secondary outcomes related to eating pathology and medical complications of obesity. The study randomized 306 patients to receive either CBT via telehealth or standard post-op bariatric care.

On the primary question, the answer was clear. No effect. People lost the same amount of weight whether they got CBT or not. On secondary outcomes, they apparently found no differences in the medical complications of obesity. The report of this study makes no mention of those measures. But on the six measures related to eating pathology, they found significant differences in four of them.

So the full story here is that CBT doesn’t really help with weight outcomes after metabolic surgery, though it seems to help with eating behaviors and psychological health factors like anxiety.

Should We Be Surprised?

Really, if not for the prevalent bias about obesity, these results should surprise no one. Weight regulation is a function of physiology for the most part. For decades now, we’ve been trying to treat obesity by getting people to behave differently and it has been largely ineffective. Surgery is effective because it addresses the problem of physiology. Now we have new drugs that can be very effective because they, too, address the problem with physiology.

So now, we can get back to the real value of psychological support in obesity – to improve mental health. This includes disordered eating and anxiety measures for which these investigators saw improvements.

It makes perfect sense that CBT would help with these outcomes and much less sense that anybody thought it would help substantially with the physiological outcome of body weight.

Old biases die hard.

Click here for the study, here and here for reporting on it.

Illustration for the Russian Fairy Story of Salt, art by Ivan Bilibin / WikiArt

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August 10, 2023