The Truth About Diet Drugs, Part 2

Why we should be extremely wary of new diet drugs being hailed as "miracles."

This post is from my previous newsletter, Food Psych Weekly.

This week’s question is from a reader named Anne. A quick content note: that the names of diet drugs are discussed below, and all of the links (other than the ones to the piece I wrote) contain weight-stigmatizing content and positive portrayals of weight-loss drugs, so take care of yourself and maybe don’t click on anything if you’re feeling vulnerable. Anne writes:

Can you weigh in on GLP-1 agonists [the trendy new class of injectable weight-loss drugs]? Thanks!!

Thanks, Anne, for that great question. Before I answer, just my standard disclaimer:

These answers are for informational and educational purposes only, aren’t a substitute for individual medical or mental health advice, and don’t constitute a provider-patient relationship.

I first wrote about these drugs two years ago, back when one of them was approved by the FDA, but I’ve been meaning to revisit the topic now that they’re so much in the public discourse (largely because celebrities are taking them and influencers are touting them, creating shortages among people who use these drugs for their original use of managing diabetes). So your question comes at a good time.

The short answer to your question is that I’m still not a fan of these drugs and wouldn’t recommend them. I think they’re problematic for many reasons, and that we’re likely to see safety concerns emerge with them over the next few years as more and more people start taking them, as has happened with a number of “miracle” diet drugs in the past.

For the longer answer, read on.

First, for anyone who doesn’t know, GLP-1 agonists are a class of diet drugs that were originally developed to treat diabetes but are now being prescribed (in many cases off-label) for weight loss. Two of the most popular members of this drug class are semaglutide (sold under the brand names Ozempic and Wegovy by its creator, Novo Nordisk) and tirzepatide (sold as Mounjaro by Eli Lilly).

The drugs are typically administered as weekly injections and may have intense side effects and potential safety concerns, as we’ll discuss below. But they’ve been hailed as “miracles” because they can lead some people (not all) to experience significant weight loss that can be maintained for as long as they keep taking the drugs—though generally people regain weight quickly once they stop.

In fact, a minority of people don’t lose any weight on these drugs at all. Others lose some, but then they “plateau” far above their “goal weights,” remaining at the high end of the BMI spectrum. In some cases that can push them to start adding other drugs—combinations that may increase safety risks and bring many more side effects.

At this point I just want to pause and say that I don’t judge or blame anyone at a higher weight for taking these drugs, because the pressure to shrink your body in diet culture is very real. It’s completely understandable why larger-bodied people—as well as anyone who even feels like they’re “too fat”—would be drawn to them. The promise of being able to escape weight stigma and meet our culture’s ridiculous body standards is incredibly seductive.

Yet these drugs are marketed in a way that preys on people’s vulnerabilities, and they’re not the miracles they’re made out to be. In fact, for some people, they can be quite the opposite.

To maintain weight loss, people need to stay on these drugs long-term, no matter the side effects—but those can be brutal. The most common ones include nausea and vomiting as well as stomach cramps, diarrhea, bloating, gas, and other gastrointestinal issues, which researchers and journalists who look favorably on these drugs tend to downplay, but which can profoundly reduce the quality of life of the people taking them. Even in the absence of GI symptoms, one study found that more than 17 percent of patients taking this class of drug developed masses of undigested or partially digested food in their GI tracts, putting them at risk of gastrointestinal obstructions.

What’s more, the long-term safety of these drugs isn’t known, but there’s reason for concern. Rare but serious side effects documented in clinical trials include pancreatitis, gallbladder disease, and kidney damage. As these drugs become more widespread, more people are likely to develop these issues, which has already been the case with gallbladder disease (with higher risks for people taking these drugs for weight loss than for diabetes, and for those taking them long-term as opposed to short-term). And in studies of rodents given “clinically relevant” doses of semaglutide and tirzepatide, the drugs have been shown to cause thyroid tumors, which was concerning enough that the FDA issued a boxed warning (also known as a “black box” warning) on the drugs’ labels.

Of course, studies in rodents don’t necessarily translate to outcomes in humans, so we can’t say for sure that the same risk would apply to humans taking the drug. Still, the FDA does not take the decision to put a black-box warning label on a drug lightly. These are the most serious type of warning that the FDA can issue.Fen-Phen—the notorious diet drug that was recalled in 1997 for causing heart-valve damage—didn’t have a boxed warning, thanks to industry lobbying. Belviq, another weight-loss drug that was pulled from the market in 2020 because of cancer risks, didn’t have one, either. Given the boxed warning on these new diet drugs, it seems the safety profile of this drug class is already more concerning to the FDA than those recalled diet pills.

If the trajectory of GLP-1 agonists is anything like previous diet drugs, some of these “rare but serious” side effects may eventually be enough to get these drugs removed from the market.

Now the American Academy of Pediatrics (AAP) is recommending that pediatricians give these and other diet drugs to kids, which is a terrible idea for all the reasons outlined above, plus many others that Virginia Sole-Smith and Ragen Chastain have articulated. I haven’t had a chance to write my own piece about the AAP guidelines, but I don’t know that I have much to add beyond what those folks and others have said. The AAP guidelines are a disaster, riddled with conflicts of interest including the fact that many of the guidelines’ authors took money from Novo Nordisk, which is also a “Patron” of the AAP that donated “between $25,000 and $49,999 to the organization,” as Ragen reported.

A few weeks ago, I was listening to a podcast interview with a journalist who’d written a glowing review of these new drugs. The interviewer asked if she had any financial ties to the pharmaceutical companies that make these drugs, and she said no. The moment felt like it was supposed to be significant, but I couldn’t help but laugh: of course a journalist isn’t likely to have any entanglement with pharmaceutical companies—but nearly all the researchers she cites in her article have consulted for Novo Nordisk, the maker of semaglutide. Among the two researchers quoted who don’t have any documented relationships with pharma companies, one is the head of research at Weight Watchers.

When you read glowing news reports about these drugs, I’d recommend keeping these conflicts of interest in mind—and, if you can, taking the long view. Diets and diet drugs come and go, and they all tend to get framed as “miracles” at first. The long-term outcomes are almost always far less rosy.

I hope that’s helpful in starting to unpack some of the issues with these drugs, Anne, and thanks again for the great question.