The weight loss shots you’ve been hearing about are a class of injectable medications that mimic gut hormones to reduce appetite and help people lose a significant amount of body weight. The two most well-known are semaglutide (sold as Wegovy) and tirzepatide (sold as Zepbound), both FDA-approved specifically for chronic weight management. In clinical trials, people on these medications lost between 15% and 20% of their body weight over about a year and a half.
The Main Medications and Their Brand Names
There are two drugs dominating the conversation, and each one has two brand names depending on whether it’s prescribed for weight loss or diabetes. Semaglutide is marketed as Wegovy for weight loss and Ozempic for type 2 diabetes. Tirzepatide is marketed as Zepbound for weight loss and Mounjaro for diabetes. The active ingredient is the same within each pair, but the weight loss versions are typically dosed higher.
Wegovy’s target dose is 2.4 milligrams per week, while Ozempic for diabetes tops out at 2 milligrams (and often stays at 0.5 or 1 milligram). Mounjaro and Zepbound use the same dosing range, with a maximum of 15 milligrams per week for both. When people say they’re taking “Ozempic for weight loss,” they’re often using the diabetes version off-label, sometimes because of insurance coverage or availability.
How the Shots Work
These medications mimic hormones your gut naturally releases after you eat. When you consume food, your intestines produce a hormone called GLP-1 that signals to your brain that you’re full. The drugs activate the same receptors, but at much higher and more sustained levels than your body produces on its own.
The effect works on multiple levels. In the brain, the medications act on the hypothalamus, the region that regulates hunger and food intake. They stimulate neurons that increase feelings of fullness while suppressing the neurons that drive hunger. This creates a genuine reduction in appetite, not just willpower. People on these medications consistently report less interest in food, fewer cravings, and a lower preference for high-calorie foods. Some research also points to changes in food reward pathways, meaning the intense pull toward rich or fatty foods becomes weaker.
In the digestive system, these drugs slow how quickly your stomach empties after a meal. That “still full” feeling after eating lasts longer, so you naturally eat less. Tirzepatide (Zepbound/Mounjaro) works on two hormone receptors instead of one, targeting both GLP-1 and another gut hormone called GIP, which may explain why it tends to produce somewhat greater weight loss.
How Much Weight People Actually Lose
The clinical trials for these drugs are some of the most impressive in the history of obesity treatment. In the major trial for semaglutide 2.4 mg (the Wegovy dose), people without diabetes lost an average of 14.9% of their body weight over 68 weeks, compared to just 2.4% in the placebo group. For someone weighing 250 pounds, that translates to roughly 37 pounds. When combined with intensive behavioral support and a low-calorie diet, the average loss climbed to 16%.
Tirzepatide performs even better. A head-to-head trial published in the New England Journal of Medicine found that tirzepatide produced an average weight loss of 20.2% at 72 weeks, compared to 13.7% for semaglutide. That’s a meaningful difference, roughly 50 pounds versus 34 pounds for a 250-pound person.
Longer-term data from a two-year trial showed semaglutide maintained a 15.2% weight reduction at 104 weeks, confirming the weight stays off as long as you keep taking the medication. Stopping treatment, however, typically leads to regaining much of the lost weight, which is why these drugs are considered long-term, possibly lifelong, treatments.
What Getting the Shot Is Like
Both medications come in pre-filled injection pens similar to what people with diabetes use for insulin. You inject once a week, on the same day each week, at whatever time is convenient. The needle goes just under the skin into a layer of fat, not into muscle. Common injection sites are the stomach (about two inches from the belly button), the front of the thigh, or the back of the upper arm. Rotating between these spots each week helps avoid skin irritation.
You don’t start at the full dose. Both drugs use a gradual ramp-up schedule to reduce side effects. Tirzepatide, for example, starts at 2.5 milligrams for the first four weeks, then increases to 5 milligrams, with further increases every four weeks or longer until you reach the dose that works for you. Semaglutide follows a similar escalation over several months. This slow titration is important because jumping straight to the full dose makes side effects significantly worse.
Side Effects to Expect
Nausea is the most common side effect and the one that causes the most frustration early on. It tends to be worst during the first few weeks at each new dose level and usually improves as your body adjusts. Some people also experience vomiting, diarrhea, or constipation. Eating smaller meals and avoiding greasy or heavy foods helps manage the stomach issues during dose increases.
Rare but more serious risks exist. A large study published in JAMA found that people using GLP-1 medications for weight loss had a higher rate of pancreatitis (inflammation of the pancreas), gastroparesis (a condition where the stomach empties too slowly on its own), and bowel obstruction compared to people on a different weight loss medication. These events were uncommon, but they’re worth knowing about, especially the gastroparesis risk for anyone who already has digestive motility problems.
Who Qualifies for a Prescription
The FDA approves these medications for adults with a BMI of 30 or higher (which qualifies as obesity) or a BMI of 27 or higher with at least one weight-related health condition such as high blood pressure, type 2 diabetes, or high cholesterol. A BMI of 27 corresponds to roughly 180 pounds for someone 5’7″ or 195 pounds for someone 5’10”.
In practice, getting a prescription also depends on your insurance coverage and your doctor’s judgment. Some insurers cover these medications readily, others require prior authorization with documented failed attempts at other weight loss methods, and some don’t cover them at all.
What They Cost
Without insurance or discount programs, these medications are expensive. Wegovy’s list price runs about $1,350 per month, and Zepbound’s is around $1,086 per month. A government discount program announced in late 2025 aims to bring prices down to roughly $350 per month for both, though eligibility and availability vary. Manufacturer savings cards and copay assistance programs can also reduce out-of-pocket costs significantly for people with commercial insurance. If you have no coverage at all, the full retail price remains a major barrier for most people.