Different Weight Loss Injections and How They Work?

If you have struggled to lose weight with just diet and exercise alone, injection for weight loss may be an option to consider.

There are several different types of weight loss injections available. These medications work through various mechanisms within the body to enhance weight loss results.

Some impact appetite and cravings, some increase resting metabolism, and others limit the absorption of consumed fats from food.

How do weight loss injections lead to weight loss?

Weight loss injections are administered either daily, weekly, or monthly depending on the medication. Most of these injectables lead to weight loss through one or more of the following mechanisms:

● Suppressing appetite — By impacting hormones that control hunger and fullness, these injections essentially work to eliminate food cravings. With a drastically reduced appetite, people consume far fewer calories which drives fat loss over time.

● Increasing resting metabolism — Some weight loss injections raise your daily resting metabolic rate even while sedentary. A revved up metabolism passively burns more calories around the clock.

● Limiting fat absorption — Preventing consumed fat from being absorbed means some of those fat calories pass through the body rather than getting stored.

Below we’ll explore the most popular prescription medications for weight loss that are administered through injection.

Saxenda

How it works: Saxenda impacts appetite regulation by mimicking the effects of a hormone called GLP-1. This hormone is released after eating a filling meal, and it dials back appetite substantially. Saxenda taps into this natural mechanism.

Dosage: Self-injected once daily

Expected weight loss: 5–10% body weight over 3–6 months

Saxenda is one of several GLP-1 drugs used for weight loss. It leads to substantial appetite suppression within 30 minutes of dosing, helping dieters stick to a reduced calorie meal plan. Nausea is the most common side effect.

Contrave

How it works: Contrave is a combination of two medications — naltrexone and bupropion. Naltrexone impacts appetite and seems to amplify metabolism-boosting nerves. Bupropion also dials up resting metabolism markedly. This dual effect drives major weight loss.

Dosage: Self-injected monthly Expected weight loss: 5–10% body weight over 6 months

Contrave stands out as both an appetite suppressant and metabolism booster. The naltrexone may prevent overeating by blocking food reward signals. Bupropion lifts metabolic rate through effects on norepinephrine and dopamine.

Wegovy

How it works: Wegovy is essentially a higher dosage version of semaglutide, the same active ingredient as Saxenda. It stimulates appetite reducing pathways more powerfully.

Dosage: Self-injected weekly

Expected weight loss: 10–15% body weight over 1 year

With its ability to slash calorie intake drastically, Wegovy appears uniquely effective for weight loss. However, the higher semaglutide dosage in Wegovy also commonly causes persistent nausea and vomiting.

Ozempic

How it works: Ozempic is a lower dose semaglutide injection, with moderately potent effects on appetite and food motivation pathways.

Dosage: Self-injected weekly

Expected weight loss: 5–10% over 6 months

Ozempic leads to solid weight loss results through appetite reduction. It may also minimize blood sugar spikes after meals, providing metabolic benefits beyond just fat loss. Side effects are less common with Ozempic than Wegovy.

The choice between Saxenda vs Ozempic vs Wegovy depends largely on:

● Weight loss goals — Wegovy tends to produce the most weight loss, followed by Saxenda and then Ozempic. Those desiring over 10% weight loss may benefit most from Wegovy.

● Side effect tolerance — Wegovy commonly causes persistent nausea/vomiting. Saxenda and Ozempic have milder side effects overall.

● Health insurance coverage — Insurance providers have different criteria for covering specific weight loss injections. Affordability may dictate which option you choose.

No matter which injection you use though, combining medication with improved nutrition and fitness helps sustain fat burning. Most patients use weight loss injections alongside lifestyle changes for optimal physical transformation.

Mysimba

How it works: Mysimba combines bupropion and naltrexone, the same active ingredients as Contrave. These medications seem to turn up metabolism while reducing appetite and food cravings.

Dosage: Oral tablet taken twice daily

Expected weight loss: 5–10% body weight over one year.

While Contrave is injectable, Mysimba offers a pill-based alternative combining bupropion and naltrexone. Limiting dietary fat absorption may also contribute to weight loss with Mysimba supplementation.

Qsymia

How it works: This oral medication combines immediate-release phentermine with extended-release topiramate. Phentermine excites metabolism-controlling nerves, while topiramate may dial back appetite and food motivation.

Dosage: Oral capsule taken once daily

Expected weight loss: 8–10% body weight over one year

Among oral weight loss options, Qsymia appears most effective — sometimes rivaling prescription injection results. However, the phentermine component increases heart rate and blood pressure requiring monitoring.