How do GLP-1 drugs work?

GLP-1 drugs, such as Ozempic and Wegovy, have been taking the food industry by storm.

They have the potential to radically reduce food waste due to a reduction in food consumption, they could potentially halve obesity, and they could lead to an increase in fortification. Some research even suggests they could lead to a reduction in alcohol consumption.

However, there may be more to them than even these outcomes suggest. Not only do they suppress appetite, but they could change the way we think about food altogether.

Is appetite suppression physiological or neural?

GLP-1 drugs are appetite suppressants, meaning that they make it easier for users to resist consuming large amounts of food, and especially certain types of food.

According to Faris Zuraikat, assistant professor at Columbia University, this is both a physiological and neural process, although more significantly neural.

GLP-1 is a hormone and is produced endogenously (by the body), he explains, but some evidence suggests that GLP-1 drugs are entering the brain more effectively than the endogenous hormone.

The drugs are, he suggests, acting on reward and other related pathways in the brain, and potentially shift food choices.

These drugs, suggests Phiala Mehring, sensory experience director at MMR Research, are far more than just appetite suppressors. They may also change how we think about food.

Zuraikat goes further, suggesting that while the drugs can result in some physical symptoms of satiety, such as nausea, they are “more potently driving the neural control of food intake.”

How do GLP-1 drugs alter tastes?

GLP-1 drugs also have the potential to affect how people taste. These changes will likely include baseline ones affecting all users, suggests Zuraikat, but also changes specific to individuals.

GLP-1 receptor agonists, he suggests, are enhancing the susceptibility of users to sweets and bitters, but not as much for salty tastes.

Research on the desirability, or “implicit wanting,” of foods, suggests Zuraikat, has shown that it’s the more energy dense and higher fat foods that people are rejecting. However, it doesn’t seem to be inhibiting the intake of low-fat sweet foods as much, even though the drugs increase sensitivity to them.

“Despite having a slightly increased sensitivity to sweet concentrations, so you need a lower concentration to get that satisfaction, there’s not a reduction [of interest in] sweet foods.”

The liking of sweetness is innate, adds MMR Research’s Mehring. Research has shown that even a foetus likes sweet tastes.

Such changes to the way people enjoy foods could have a knock-on affect to the way they choose foods.

“I think people will probably start doing a bit more of cost-benefit analysis when choosing what to eat and how much of it to eat,” explains Paulina Lang, head of behavioural science at MMR Research.

For example, while psychologically they may feel more comfortable with allowing themselves the occasional treat, they may not have the appetite. In other words, “they may not be able to do that because their body is not allowing them to to do it.”

This approach will extend to whether they take the drug or not in the first place. “They will look at the benefit of the drug - losing weight - and then the cost of it - not being to enjoy the food that they used to enjoy - and decide, is it worth it? Is it something that I’m willing to to give up on?”

Can foods play the same role as GLP-1 drugs?

Some companies are responding to the rise of GLP-1 drugs by developing foods which aim to increase satiety in the same way. Could these fulfil the same role?

“I think a lot of people would be more comfortable with the idea of not needing to rely on medication,” said MMR Research’s Lang. However, “the problem is you are reintroducing the aspect of motivation.”

The beauty of GLP-1 drugs, she suggests, is that they remove the need for the user to be motivated to eat in a certain way, meaning that they do not even want to eat certain unhealthy foods. With food engineered for satiety, this aspect is added back into the mix.

“If you choose the food that provides similar effect, you need to be consistent in your choice of that food.

“So you’d still need to be motivated to eat that food and then that food needs to be really attractive and it needs to be accessible.”

While a satiety-promoting diet can be successful, Columbia University’s Zuraikat explains, this may be offset by certain adaptations.

“There are physiological and psychological adaptations to weight loss that promote eating and motivation for energy dense foods,” he says.

Furthermore, while GLP-1 can be produced endogenously, which is instigated by food, Zuraikat explains, this is not as potent as that produced by the GLP-1 drugs and so cannot be as effective.

“This will never be as effective as the the drugs because the half life of endogenous GLP-1 is a few minutes. It’s not that potent of a satiety promoting hormone endogenously.

“What they’ve done is they’ve manufactured the molecule so that it has a much greater half life, and that it can actually infiltrate the brain more effectively.”