Dr Giles Yeo is a geneticist with 20 years’ experience studying obesity. He is Principal Research Associate at the Metabolic Research Laboratories and MRC Metabolic Diseases Unit, University of Cambridge.
News that a weekly injection of the drug semaglutide caused an average 15kg weight loss over 15 months in a new study is a game changer for those living with obesity.
The scientists involved say the results could mark a “new era” in treating obesity – and I agree. To lose that much weight over that short a period of time is spectacular, especially with a weekly single injection.
Semaglutide is created from GLP1, a natural gut hormone in our body, but is an artificial, longer lasting version that mimics the feeling of feeling full – which is everything when it comes to losing weight.
When we eat, food goes down our stomach, into our small intestines and out the other side. Our natural gut hormones signal to the brain what we’re eating and how much, which makes us feel full, but these hormones tend to have a short effect, hence us soon feeling hungry and wanting to eat more. Semaglutide, however, lasts longer in circulation so more of it hits the brain.
The only other artificial way to produce GLP1 is through bariatric surgery, effectively replumbing your guts, but this is a serious operation that carries a significant risk and is not something to be rolled out across the population. A similar principle should apply, I believe, to this drug.
Is it a drug you’d want to roll out to every single human being who’s just a little bit heavy? If you want to lose a few pounds, for example, would it work for you? It’s currently being submitted to drug regulators but once the safety and trials are completed, this will be up for discussion. In my view, it should be used for those in whom obesity is a clear and present risk to health and need to lose weight now, not for those who are just a little overweight.
Obesity drives so many other diseases, such as heart disease and cancer, and we have to weigh up the risk/gain balance and discuss where the threshold lies; when is a person too large and too at risk and when would a lifestyle intervention be better?
For those of us who want to lose a few pounds or can’t shift that stubborn half stone, making diet and fitness changes are likely to be more appropriate. High-protein diets such as Atkins, keto or the paleo diets, produce GLP1 naturally and trigger a similar but less dramatic feel-fuller-eat-less effect, albeit with a lot more discipline and effort than simply having a weekly injection.
We have to think about the side effects too. Some of the 2,000 people in the study suffered side effects to the treatment including nausea, diarrhoea, vomiting and constipation.
Too many gut hormones make you feel full but can also make you feel sick. Clearly you have to be careful about the amount, which is why the once-weekly schedule is important because you’re less likely to put too much in. Gut peptides also play a big role in speeding or slowing the transit of food. How this reacts with an individual – whether through diarrhoea or constipation – will depend on a person’s individual physiology, how much food is being eaten and how sensitive you are. No one wants to feel sick. For the majority of the population, semaglutide is likely to be tolerable or have no side effects whatsoever – but it is something that needs to be considered when thinking of it being rolled out and who should receive it.
There’s the question of its long-term effect, too. One woman in the study started putting on weight as soon as she came off the drug and this is just the way biology works. The moment the drug is taken away, the eating behaviour will go back to the way it was before and the weight will pile on.
In principle, it should be possible to stay on the drug long term since bariatric surgery permanently changes the levels of GLP1 and people stay perfectly healthy and slim afterwards, so there’s no reason semaglutide can’t work in the same way, but more studies need to be done.
In the meantime, this study is very exciting for those of us working in the obesity world. While in the past, the last chance option has always been surgery, this opens up the possibility of a cure to the obesity crisis for the wider population, not just for those whose lives are threatened by their weight.
The next stage will be converting the injection into a pill and I’m sure dozens of pharmaceutical companies are working on that as we speak. The problem with a pill is getting it past the stomach, which digests and destroys everything, so the amount of GLP1 would need to be considerably higher. I think it will happen – it’s just a matter of how and when.
As told to Lauren Libbert
Gene Eating: The Story Of Human Appetite, by Dr Giles Yeo is available from Telegraph Books for £9.99
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