Orlistat for Weight Loss: How Does Orlistat Work

Discover how Orlistat can support your weight loss journey and help you take control of your health. Learn about common side effects and interactions.

Table of Contents
  • What is Orlistat?
  • How Does Orlistat Work?
  • Who Qualifies for Orlistat?
  • Can Orlistat Be Used For Weight Loss?
  • Orlistat vs Other Prescription Weight Loss Medications
  • Orlistat Side Effects
  • Orlistat Dosage and Administration
  • Orlistat Contraindications and Warnings
  • Orlistat Coverage and Cost
  • Where Can I Get Orlistat?
  • References

Among all of the weight loss medications on the market today, Orlistat may be familiar. Orlistat has been used to help people lose weight for over two decades. It may have fallen out of favor due to the advent of other prescription weight loss medications, such as the GLP-1 agonist medications or Contrave and Qsymia. However, it still may be a perfect fit for your particular weight loss journey. In this post, we will review Orlistat for its use in weight management and help you determine if it is a good choice for you. 

What Is Orlistat?

Orlistat is an FDA-approved prescription weight loss medication for the management of obesity. It is commonly sold under the names Xenical and Alli. Alli is a lower-dose form of medication that is available over the counter, while Xenical is a prescription medication that is given at a higher dose. 

How Does Orlistat Work?

Orlistat works by inhibiting the action of enzymes in the digestive system that break down fats, thereby reducing the amount of fat absorbed by the body. This leads to a decrease in calorie intake and can result in weight loss. 

Orlistat for Weight Loss

Orlistat has been on the market for weight loss for over two decades. A study published back in 1998 looked into how effective Orlistat was on weight loss and preventing weight regain for patients struggling with obesity. Participants were given 120 mg of Orlistat as well were placed on a calorie-restricted diet (600kcal/day deficit) for a 52-week period. When the study concluded, participants taking orlistat lost around 10.3 kg (22 lbs) after the year, which was significantly more than the placebo group. When the placebo group was started on Orlistat and monitored for an additional year, they noticed an additional 0.9kg loss in weight. 

However, due to the side effects and the existence of newer and more effective medications, some providers may recommend starting a different medication before offering Orlistat. 

Information About Orlistat

Administration and Dosage

Orlistat can be given in a prescription form (Xenical)or over-the-counter form (Alli). Xenical is started as a 120 mg pill taken three times a day with each main meal that contains fat.  Alli is given as a 60mg pill in the same manner. Either form should be taken during a meal or up to one hour after. If a meal has no fat, then you can skip the dose. 

This medication must be taken with a nutritionally balanced, reduced-calorie diet containing approximately 30% of calories from fats. It is also important to ensure you efficiently take fat-soluble vitamin supplements (D, E, A, and K) to prevent deficiency. Also, you may benefit from taking supplements or eating foods that contain healthy fats, such as Omega 3 and Omega 6 fatty acids. For best results, you should also engage in regular exercise of about 150 minutes per week. 

Side Effects

Since Orlistat effectively prevents your body from absorbing fats, one of the most common side effects patients notice is oily or fatty stools. Other common side effects include oily spotting in your underwear, gas, loose stools, stomach pain, and nausea. You may become deficient in fat-soluble vitamins, which include vitamins D, K, A, and E. You may also reduce the amount of essential fats (Omega 3, Omega 6) you take daily. Therefore, you must take this medication under the supervision of a licensed medical provider and take supplements to replace these lost vitamins and fats. 

Cost and Coverage

Orlistat is available over the counter or as a prescription medication. The over-the-counter version, Alli, can cost around $50-$65 for a 30-day supply. Xenical can cost up to $555 for a 30-day supply. For this reason, your provider may recommend starting with Alli. You may be eligible for a Xenical Coupon to help cover the price. 

Where Can I Learn More?

If you would like to learn more about GLP-1 medications or want to see if you might be eligible for medication-assisted weight loss, check out Mochi Health, where board-certified obesity medicine physicians can offer expertise in this realm!


  1. Sjöström L, Rissanen A, Andersen T, Boldrin M, Golay A, Koppeschaar HP, Krempf M. Randomised placebo-controlled trial of orlistat for weight loss and prevention of weight regain in obese patients. European Multicentre Orlistat Study Group. Lancet. 1998 Jul 18;352(9123):167-72. doi: 10.1016/s0140-6736(97)11509-4. PMID: 9683204.

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