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Orlistat (Alli®) for Weight-Loss: How Does It Work?

Orlistat (Alli®) for Weight-Loss: How Does It Work?
Dr. Constance Odom, MD Picture of Dr. Constance Odom, MD

Medically reviewed by

Written by our editorial team.

Last Edited 8 min read

Orlistat is the generic name of a medication that helps people lose weight by preventing the absorption of some dietary fat. You have probably seen Orlistat in the pharmacy’s weight-loss section under the brand names Alli® or Xenical and wondered how it worked. 

Nu Image Medical’s doctors prescribe orlistat as part of the WAYT-less weight-loss program, which includes doctor-prescribed medications, “The WAYT-less Diet” ebook, and, if possible, regular exercise.

Read on to learn how Orlistat helps people lose weight and what you can expect if you use it to enhance your own weight-loss efforts. 

How Does Orlistat (Alli®) Work? 

Gastric and pancreatic lipases are enzymes used by your body to break down triglycerides, a type of fat so that you can more readily absorb them. Orlistat is a lipase inhibitor that limits the action of lipase so that your body eliminates fat instead of absorbing it. This reduces how much fat your body absorbs from the foods you eat and helps to create a calorie deficit so you can more easily lose weight. 

Studies have shown that Orlistat can inhibit fat absorption up to 30%. This means that if you maintain a diet of 2,000 calories a day with 30% fat, around 200 of those calories will not be absorbed, creating a deficit. This makes it easier for you to lose weight and can also help sustain weight loss.  

Because of the way orlistat works to block fat absorption, it has other benefits as well. For instance, taking Orlistat has been shown to lower blood lipids and can improve insulin sensitivity. It may also help regulate blood pressure. When taken as directed, Orlistat is a safe way to lose weight that is more effective than dietary restrictions and exercise alone. 

Side Effects of Taking Orlistat (Alli®)

Orlistat is a safe medication that is well tolerated by most people. However, as with all medications, it is important to understand how it works and what you might experience when you take it. Some potential side effects include gas, bloating, diarrhea, and skin rash or itching. More serious side effects, like abdominal pain or vision changes, are uncommon but if they occur you should discontinue use and consult a physician. 

You can reduce some of the unwanted side effects of taking Orlistat by controlling the amount of fat you consume. By keeping your fat intake at around 30% of your daily calories, you’ll see the benefits of the medication with fewer side effects. But remember, you do not want to remove all fat from your diet, otherwise Orlistat will be less effective.

You should be aware of some of the other things you may experience when you take Orlistat. For instance, you may notice that you have loose stools or need to go to the bathroom more often. This is because Orlistat prevents your body from absorbing fat, but moves it through your system and eliminates it through bowel functions. This is normal and is a sign that Orlistat is working correctly. 

How to Lose Weight With Orlistat 

Orlistat can be a powerful tool to help our patients drop stubborn weight, but for the best results, we recommend following a healthy diet. Every weight loss regime benefits from keeping calories under control. By reducing your caloric intake along with taking Orlistat, you are likely to see better results from your weight-loss program. 

What you eat is also important. By swapping out unhealthy, low-nutrient foods for whole, nutrient-dense choices, you will see better overall results. Lean meats along with a healthy mix of veggies and low-glycemic fruits will give you energy while helping you keep your calorie count low. 

Don’t forget: Everything you consume counts, so keep track of sauces and condiments as well!

Orlistat helps to create a calorie deficit, but you can increase this even more by revving up your activity level. This could mean starting a regular exercise program, but you can also find ways to get more movement from the things you do every day. Simply using the stairs or parking further away from the entrance will provide you with more calorie-burning opportunities.

Using Acarbose and Naltrexone to Boost Weight Loss

There is a limit to how quickly the body can shed fat, but that doesn’t mean you cannot take steps to speed things up. One way you can enhance your weight-loss efforts is to add Acarbose and Naltrexone to your routine. These medications can be safely used with Orlistat to provide you with an edge on your weight loss journey. As with all medications, side effects with Acarbose and Naltrexone may occur.

Acarbose (Precose®) is a prescription medication that slows down how quickly your body digests carbohydrates. This helps to control blood sugar spikes and create an environment for weight loss. Naltrexone is a prescription medication that acts as an appetite suppressant. Taking it will help control cravings which can make it easier to stick to a healthy, reduced-calorie eating plan.

Taking these three medications together can reduce the amount of fat and carbs your body absorbs while slashing your appetite. You will have more energy and feel less hungry, which will make it a lot easier to stick to your weight loss plan. 

Reach Your Goal With WAYT-less™ 

We created the WAYT-less™ weight-loss program to leverage the benefits of Orlistat, Acarbose, and Naltrexone. By taking all three medications together, our clients are able to improve their diets, shed fat and achieve sustainable weight loss. And while exercise is not required for success in the program, it will help you reach your weight loss goals even quicker. 

In the WAYT-less™ program, these three medications are split into two daily doses consisting of a capsule with Orlistat and Acarbose and one with a low dose of Naltrexone. This makes it very easy to manage, even if you have a busy schedule or if you’re someone who tends to forget to take medications. Simply take the medication as prescribed and eat sensibly and you’ll start to see results.


When you sign up for the WAYT-less™ program you will meet with one of our experienced physicians through telemedicine. They will learn about your overall health, your weight-loss goals and help determine if this is the right path for you. If it is, they can prescribe the medication and offer you nutrition and exercise guidelines to help you reach your weight-loss goals in a healthy, sustainable way.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your physician about the risks and benefits of any treatment. Nu Image Medical may not offer the medications or services mentioned in this article.