Woman forming heart shape over her stomach to represent orlistat vs ozempic weight loss results

Orlistat vs. Ozempic®

Written on September 26, 2023 by Lori Mulligan, MPH. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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Orlistat vs Ozempic® differ in how they cause weight loss. Older weight loss drugs, like Orlistat (Xenical® or Alli®), affect how much fat you absorb from food, largely based on the idea that fat intake causes obesity. Most current anti-obesity medications, such as Ozempic®, target appetite regulation (that is, they make you feel fuller for longer, decreasing your appetite). Some are oral medications (taken by mouth) while others are self-administered, once-a-week injections.

Ozempic® is actually FDA-approved as a diabetes medicine that is prescribed off-label for weight loss. Its active ingredient is semaglutide. The FDA-approved drug for weight loss using this active ingredient is Wegovy®, which is a slightly higher dose than Ozempic®.

Let’s take a closer look at how effective these drugs are at weight loss and consider what are the potential side effects of each.

Orlistat (Xenical® And Alli®)

Orlistat works by slowing the absorption of fat in the intestine by about 30%. It is approved for long-term use.

About 6 lbs (3 kg) or up to 6% of body weight can be lost when using this medicine. But not everyone loses weight while taking it. Many people regain most of their weight within two years after they stop using it.

Xenical® is the brand of orlistat your provider can prescribe for you. You can also buy orlistat without a prescription under the name Alli®. These pills are half the strength of Xenical®. Orlistat costs about $100 or more a month. Consider whether the cost, side effects, and small weight loss you can expect are worth it to you.

Your body may not absorb important vitamins, minerals, and other nutrients from food while you are using orlistat. You should take a daily multivitamin if you use orlistat.[1]

According to the Cleveland Clinic, you should use this medicine with a reduced-calorie diet that contains no more than about 30% of the calories from fat. Divide your daily intake of fat, carbohydrates, and protein evenly over your three main meals. Follow a well-balanced, reduced-calorie, low-fat diet. Try starting this diet before taking this medicine. Following a low-fat diet can help reduce the possible side effects of this medicine.

What Potential Side Effects May I Notice When Taking Orlistat?

Side effects that you should report to your doctor or health care professional as soon as possible:

  • Allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
  • Breathing problems
  • Bloody or black, tarry stools
  • Signs and symptoms of kidney stones like blood in the urine, pain in the lower back or side, pain when urinating
  • Signs and symptoms of liver injury like dark yellow or brown urine; general ill feeling or flu-like symptoms; light-colored stools; loss of appetite; nausea; right upper belly pain; unusual weakness or fatigue; yellowing of the eyes or skin
  • Trouble passing urine or change in the amount of urine
  • Uncontrolled, urgent bowel movements
  • Vomiting

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome) [2]:

  • Gas
  • Increased bowel movements
  • Oily stools (may be clear, orange, or brown)
  • Upset stomach

Everlywell Weight Loss Support


Ozempic® is a drug you inject once a week in your thigh, abdomen, or upper arm. It’s in a class of medications called GLP-1 receptor agonists, or GLP-1 drugs for short. These medications mimic a hormone released from the digestive tract called glucagon-like peptide (GLP-1), which helps lower blood sugar and promotes a feeling of fullness.

Research has proven that higher doses of Ozempic®—2.4 mg of semaglutide—are very effective for reducing weight in people with obesity. In one landmark study, people with obesity who used the drug in combination with lifestyle interventions lost about 15% of their body weight in 68 weeks. They lost about 34 pounds on average. Research participants who didn’t take the medication lost about six pounds on average.[3]

What Are The Potential Side Effects Of Ozempic®?

Check with your doctor immediately if any of the following side effects occur.

Less common:

  • Belching
  • Bloated, full feeling
  • Excess air or gas in the stomach or intestines
  • Gaseous stomach pain
  • Heartburn
  • Passing gas
  • Recurrent fever
  • Stomach discomfort, fullness, or pain
  • Yellow eyes or skin


  • Burning feeling in the chest or stomach
  • Indigestion
  • Stomach upset
  • Tenderness in the stomach area

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your healthcare professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common:

  • Diarrhea

Less common:

  • Constipation
  • Hair loss

Rare [4]:

  • Bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site
  • Change in taste
  • Loss of taste

Everlywell Offers Online Weight Loss Program And Metabolism Test

Everlywell's comprehensive Weight Care+ program pairs GLP-1 prescriptions with regular clinician care, lab testing, and support for related conditions. Specifically, you get:

  • Access to GLP-1 prescriptions for qualified candidates
  • Regular 1:1 virtual visits with a licensed clinician
  • Included quarterly at-home lab tests or supplements
  • Lifestyle content and support for health conditions

To test hormones that may be related to unexpected changes in weight and energy try Everlywell’s metabolism kit. This at-home lab test measures three hormones that can influence your metabolism and may help you understand unexpected changes in weight and energy.

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  1. Weight-loss medications. Mount Sinai. https://www.mountsinai.org/health-library/selfcare-instructions/weight-loss-medicines. Updated on 7/8/2023. Accessed on 9/12/2023.
  2. Orlistat capsules. Cleveland Clinic. https://my.clevelandclinic.org/health/drugs/19489-orlistat-capsules. Accessed on 9/12/2023.
  3. Is Ozempic® the answer for weight loss? Cleveland Clinic. https://health.clevelandclinic.org/Ozempic-for-weight-loss/. Published on 3/30/2023. Accessed on 9/12/2023.
  4. Semaglutide. Mayo Clinic. https://www.mayoclinic.org/drugs-supplements/semaglutide-subcutaneous-route/side-effects/drg-20406730?p=1. 9/23/2023. Updated on 9/1/2023. Accessed on 9/12/2023.
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