Fat or Tasteless?

A possible sensory link to Ozempic face

With apologies to Eric Cartman.

Ozempic, a drug originally developed to treat type 2 diabetes, has become enormously popular as a weight-loss medication. The trend has been promoted by the many celebrities who acknowledge taking it, and by the dramatic before and after photos posted on social media.

One notorious effect of the treatment can be a reduction in the fat deposits on the user’s face and neck, resulting in a dramatic change of appearance known as “Ozempic face.”

I have little interest in celebrities or their jowls (saggy or otherwise), but I have often wondered how exactly Ozempic produces its effect on body weight.

Ozempic is the best-known example of a class of drugs known as glucagon-like peptide-1 receptor agonists (GLP-1 RAs). Mounjaro, Zepbound, and Wegovy also belong to this class. Apparently, these compounds decrease food intake by reducing feelings of hunger and “the desire to eat sweet, salty, fatty, or savory tasting foods.” Okay, but how is this lack of desire brought about? In particular, is it mediated by alterations in the smell or taste of food?

Until recently, only one paper had examined the sensory effects of GLP-1 RAs, and it was small and poorly designed. Now, a definitive study has been published by Rafa Khan and Richard L. Doty at the University of Pennsylvania. Doty is a longtime sensory researcher who markets a widely used smell test, and who has studied altered sensory response in a wide range of diseases and medical conditions.

Kahn and Doty used a case-control experimental design. They recruited a group of adults who were taking GLP-1 RAs and another group—matched for age, sex, smoking, and COVID history—who were not.

Each person was tested for smell and taste. Smell identification ability was assessed with Doty’s 40-item scratch-and-sniff UPSIT test. Taste was assessed with another of Doty’s marketed kits: a 53-item set of plastic taste strips that include sweet (sucrose), sour (citric acid), salty (sodium chloride), bitter (caffeine), and savory/umami (monosodium glutamate). Each participant got four concentrations of each stimulus twice. Their task was to identify the sample as tasting either sweet, sour, salty, bitter, or savory.

The results were clear. People taking GLP-1 RAs scored worse than matched controls on the taste identification test, both overall and for each of the five basic tastes. However there was no significant difference between the groups on the smell identification test.

I was a bit surprised by the outcome (and I bet Doty was too). Why? Because food cravings and hunger are usually linked to smell. It’s smelling a pizza shop as you walk past that drives the desire for pizza. It happens before you buy the slice, not after you’ve taken the first bite.

In any case, it now seems clear that Ozempic dulls the user’s taste sensations, which leads to a lack of interest in eating.

Anecdotal evidence suggests that Ozempic effects go beyond reduced taste input. Kahn and Doty’s study included an open-ended question, and the answers hint at possible chemosensory distortions among GLP-1 RA users:

For example, one subject noted that “Red meats and fish taste awful. Milk and milk products taste off.” Another reported, “Everything is overly sweet or overly sour and things leave a sour/paste taste in my mouth. I was a coke drinker since high school but now I never crave it and it’s too sickly sweet for me.” Involvement of texture was suggested by one participant who stated, “I am more sensitive to food textures.” 21.7% of the participants indicated that the flavor of foods was altered, with one noting “Scrambled eggs are intolerable and red wine tastes like an ashtray.”

Sheesh.

People with morbid obesity or acute weight-related health problems may benefit from these drugs. But is being thin and saggy for the sake of vanity alone worth the loss of pleasure in food? Count me out.

Stay jowly, my friends.

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Rafa Khan and Richard L. Doty, GLP-1 receptor agonists significantly impair taste function, Physiology & Behavior 291:114793, 2025.