Just about anyone who’s tried it knows that losing weight is hard. When calorie restriction and cardio workouts leave you tired and hungry, anything that could hurry progress seems worth a try — especially something as easy as a pill.
Americans invested $2 billion on weight-loss supplements in 2015, despite the industry’s complicated history. When it comes to diet pills, there are two types: prescription drugs, and over-the-counter supplements. And they are not created or regulated equally.
Here’s what you need to know about each and whether they can help you lose weight.
The Food and Drug Administration has approved five prescription drugs for long-term weight loss based on research about their safety and effectiveness:
A few other medications — most commonly phentermine — are approved for short-term use. But prescription weight-loss medication isn’t for everyone. Doctors often reserve these treatments for people with a BMI of over 30 kg/m or those who have obesity-related health complications, like high blood pressure or diabetes.
These pills aren’t a perfect solution for obesity. Weight-loss medications are used along with a healthy diet and exercise regimen that need to be continued after treatment. Also, side effects are common and can be severe.
There are many more diet pills available that aren’t FDA-approved or -regulated. “Federal law does not require dietary supplements to be proven safe to FDA’s satisfaction before they are marketed,” the FDA’s website says.
Since over-the-counter diet pills don’t have to be vetted for safety or efficacy, it’s much easier to get them onto shelves and into your medicine cabinet. In fact, many manufacturers of weight-loss supplements don’t test their products in humans before taking them to market.
So if you’re considering a diet-pill supplement, there are a few things you might want to know first.
These types of diet pills often contain vitamins, minerals, enzymes, and herbs. The most common ingredients can be found in a database from the National Institutes of Health. It will tell you everything that researchers know about an ingredient so far. Is it safe? Does it work? That’s where you’ll find out.
For instance, there’s Garcinia cambogia, which comes in products like Hydroxycut and Plexus Slim. It’s supposed to suppress appetite and decrease the number of fat cells your body makes. Though its considered “fairly safe,” there’s no evidence that it actually helps with weight loss, and excessive use has been linked to liver problems.
Other diet pills may contain chitosan, from the shells of crabs, lobsters, and shrimp. In theory, it’s supposed to bind fat in your digestive tract so your body can’t absorb it. In reality, according to the NIH, the amount of fat it binds is probably not enough to help you lose a significant amount of weight.
The most common ingredients are stimulants like caffeine, yerba mate, bitter orange, or guarana. When it comes to the data on these ingredients, there’s not a lot to suggest they help in any way with weight loss, said Katherine Zeratsky, a registered dietitian at the Mayo Clinic.
For example, a 2019 study found that rats given caffeine burned more calories than rats doing the same amount of exercise without a stimulant. But there is no evidence that the effect carries over to humans.
Theoretically, all these ingredients should help with weight loss, but it’s extremely difficult to figure out if they work, Zeratsky said. That’s because most diet pills are made up of multiple ingredients and the directions suggest you take them while having a diet that’s restrictive in calories. So it’s hard to tell whether you lost weight because of the product or because you simply ate fewer calories.
No matter what diet-pill ingredient or program you’re considering, it’s critical that you talk to your pharmacist first, Zeratsky said, especially if you take other medications.
Though many of the ingredients are considered safe, they can have toxic effects at high doses. And it’s possible that they could interfere with your other medications. Your pharmacist can walk you through a cryptic ingredient list and point out any red flags.