Finding Diet Drugs That Work

A series of rows of medical pills with a light blue background

Key Takeaways:

  • Effective weight loss often requires a combination of diet, exercise, and sometimes medications or surgery.

  • Injectable medications like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro) have become the most popular medical options for their significant weight loss effects.

  • Weight loss medications work through various mechanisms, primarily targeting the brain to regulate hunger and appetite.

Myths abound when it comes to weight loss, but their origins are no mystery. Whether you’re out in the world or browsing online, advertisements for weight loss supplements are everywhere, claiming extreme and unbelievable results like, “Lose ten pounds in ten days!” with no mention of lifestyle, diet, or exercise being necessary. We all want to believe in a quick fix because weight loss can be difficult to achieve and maintain, and it isn’t necessarily as simple as “eat less and move more.”

Now, injectable diabetes medications like Ozempic, Wegovy, and Mounjaro are gaining massive popularity for “off-label” use to effectively induce weight loss. The active ingredient, semaglutide, regulates insulin and blood pressure but also mimics the hormone that creates the feeling of being full. The demand for these medications has exploded, and the pill form is already in development.

While there’s no “magic pill” (or injection!), there are weight loss medications currently available that are effective, safe, and can help you achieve your weight loss goals. These medications don’t melt fat or shed inches; there are no pills that can target weight loss in specific parts of the body. In fact, most weight loss medications don’t even work in the intestines or the stomach—they work in the brain. 

How do weight loss pills work?

Here’s a look at how some of the most commonly prescribed weight loss pills work and how effective they’ve been in clinical trials:

Semaglutide (known under the brand names Ozempic and Wegovy) is an injectable medication originally used for managing Type 2 diabetes. It mimics a hormone called GLP-1, which targets areas of the brain that regulate appetite and food intake, leading to reduced hunger and increased feelings of fullness. In clinical trials, individuals taking Semaglutide for weight loss achieved an average weight reduction of 15 percent of their body weight over 68 weeks, compared with 2.4 percent in those taking a placebo.

Tirzepatide (known under the brand name Mounjaro) is another injectable medication primarily used for Type 2 diabetes but has shown significant weight loss effects. It mimics the actions of GLP-1 and GIP, hormones involved in controlling blood sugar and appetite. In clinical trials, individuals taking Tirzepatide for weight loss experienced an average reduction of up to 21 percent of their body weight over 72 weeks, compared with 3 percent for those on a placebo.

Naltrexone-Bupropion (known under the brand name Contrave) targets a part of the brain called the hypothalamus that helps your body regulate hunger. While it remains unknown exactly how this medication works to promote weight loss, it does lead to a decrease in appetite.  In one trial, 42 percent of people who used the drug along with diet and exercise lost at least 5% of their body weight in a year, compared with 17 percent of those who used diet and exercise along with a placebo (inactive) pill.

Liraglutide (known under the brand name Saxenda), similar to semaglutide, was first approved to treat people with Type 2 diabetes because it helps promote insulin production after a meal to help control blood sugar. It is prescribed as a weight loss medication at a higher dose due to its ability to act in the brain and cause a decrease in appetite.  It also slows down the emptying of the stomach causing you to feel full for a longer time after a meal and eat less during the day.  Also like semaglutide, it is not a pill; it is injected daily from a pen. A study found that 63 percent of people who took Liraglutide lost 5 percent or more of their body weight in a year, compared with 27 percent who took a placebo.

Phentermine-Topiramate (known under the brand name Qsymia) is a drug combination that can help you eat less with a two-fold mechanism. Phentermine is a medication that decreases the appetite and increases metabolism. Topiramate alone is used as a migraine and anti-seizure medication, and it also decreases appetite and causes feelings of fullness. In a clinical trial, people who took this medication lost an average of 9% of their body weight, compared with 1.5 percent of those who took a placebo pill.

Orlistat (known under the brand names of Xenical and Alli over-the-counter) is the only weight loss medication that works in the intestines.  It blocks 1/3 of the fat (and the calories that come with it) in meals from being absorbed by the body, which led to >5 percent weight loss in 65 percent of patients taking orlistat when combined with a reduced-calorie diet and exercise in a clinical trial,6  compared with 43 percent of patients on a placebo pill with diet and exercise alone.  While these studies show that diet and exercise are important, medications can help increase the amount of weight that you lose and may be a helpful addition to your weight loss program.

So are weight loss pills right for me?

Weight loss medications aren’t for everyone.  Your Body Mass Index (BMI), a measurement based on your height and weight, which is used to estimate body fat, can help you figure out if medications may be an option for you. (Find your BMI with this BMI Calculator).  If you have a BMI of 30  or higher, or if you have a BMI between 27-30 and have also developed health conditions brought on by weight, like high blood pressure, diabetes, or heart disease, then weight loss medications may make sense as part of your weight loss strategy, along with a healthy diet and exercise.

It’s important to remember that everyone is different and will lose weight in different ways. 

If you’re interested in learning if weight loss medication is right for you, call Columbia’s Weight Loss team at (212) 305-4000 or fill out our request an appointment form to learn more about your weight loss options.

  1. Ornellas, T. Chavez, B. Naltrexone SR/Bupropion SR (Contrave) A new approach to weight loss in obese adults. Available at:
  2. U.S. Food and Drug Administration. FDA approves weight-management drug Contrave. 2014 Sept 10; Available at:
  3. Pi-Sunyer, Xavier. Et al. A Randomized, controlled trial of 3.0 mg of Liraglutide in weight management. N Engl J Med 2015; Available at:
  4. Shin, Jin Hee. Gadde, M Kishore. Clinical utility of phentermine/topiramate (Qsymia) combination for the treatment of obesity. Diabetes Metab Syndr Obes 2013; Available at:
  5. Davidson, MH. Et al. Weight control and risk factor reduction in obese subjects treated for 2 years with orlistat: a randomized controlled trial. JAMA 1999 Apr 7; Available at: