Does Orlistat work for weight loss?

Are you exploring weight loss options and wondering if Orlistat is the right choice? If so, you’re not alone. Many people are turning to weight loss pills to help achieve their goals, but with so many products out there, it can be tough to know what really works.

Orlistat, known by brand names like Xenical, Orlos, and Alli, has been on the market for a while and is a popular weight loss medication. But is it effective? In this blog, we’ll break down what Orlistat is, how these weight loss tablets work, and whether they could be the right tool for your weight loss journey.

What is Orlistat?

Orlistat is a weight loss tablet that belongs to a class of medications called lipase inhibitors. It prevents your body from absorbing around one-third of the fat you eat (1). The fat that is not absorbed or stored in the body remains undigested and is passed out in your poo, helping you lose weight.

In the UK, Orlistat is available in a 120mg dosage as a prescription drug under the brand name Xenical or as a generic Orlistat. You can alternatively buy a lower dose of 60mg over the counter without a prescription from pharmacies. Over-the-counter Orlistat is available under the brand names Alli and Orlos.

How does Orlistat work?

Orlistat prevents the body from absorbing all of the fat consumed through the diet. It does this by inhibiting specific digestive enzymes known as lipases, which are produced by the stomach and pancreas. Lipases break down dietary fat so the gut can absorb it.

By inhibiting the lipase enzyme, Orlistat blocks the breakdown and absorption of fat. The drug doesn’t block fat absorption completely, but it does prevent about 30% of the fat you consume from being absorbed (1). This undigested fat then passes straight through your digestive system and out in your poo, leading to a reduced calorie intake.

Over time, this calorie reduction causes the body to use its stored fat as an energy source. As the body starts to break down its stored fat, it can lead to weight loss.

Does Orlistat work for losing weight?

Orlistat really does work for losing weight. As with all medications, results vary—some people will see more weight loss than others.

However, research suggests that combined with a healthy diet and regular exercise, this treatment can help people lose 5 to 10% of their weight within a year (2).

This weight loss far exceeds what you might expect from changing your diet alone. One study found that after six months of treatment, the average weight loss for people taking Orlistat was almost double that of those who had only switched to healthier diets (3). It can also help you keep the weight off, reducing weight regain over longer periods (4)(5).

And there’s more—not only does Orlistat help with weight loss, but it also reduces other markers of obesity and poor health. It is known to lower body mass index (BMI), waist circumference, total blood cholesterol, the levels of “bad” cholesterol (low-density lipoproteins (LDL)), and blood glucose while improving blood pressure and insulin sensitivity (3)(4)(6).

How long does Orlistat take to work?

Remember that weight loss pills are not a quick fix. Orlistat starts working in your digestive tract and blocks fat absorption almost immediately after taking it. However, it takes a while to translate to enough of a calorie deficit to cause weight loss.

You will typically begin losing weight around two weeks after you start treatment (7), but the weight loss only becomes significant after being on the medication for more than two months (3). This weight loss should be slow and gradual. You can expect to lose around 1-2lbs per week, or around 5% of your body weight in the first three months (8).

Orlistat also works best alongside comprehensive weight loss programs. For example, combining the medication with healthy lifestyle changes—such as a low-fat diet and regular exercise—can produce better results from Orlistat, meaning faster weight loss and less weight regain.

How long does Orlistat stay in your system?

Orlistat doesn’t stay in your system for very long. Many drugs need to be absorbed to start working, but this is not the case with this drug—it works directly from the gut. This is great because it can start blocking fat absorption almost instantly, but it also means the drug quickly passes out of your body.

Depending on your bowel movements and digestive tract, Orlistat is usually eliminated from the body within 12 to 72 hours after the last dose. This means it won't build up in your body over time, making it a relatively safe choice for ongoing use. However, you also need to keep taking Orlistat regularly for it to cause weight loss effectively.

How should I take Orlistat?

Orlistat is typically taken as a 120mg dose three times a day, with each main meal containing fat. To get the best results, you should take Orlistat during or up to one hour after your meal. If you skip a meal or eat a meal without fat, you can skip your dose for that meal (7).

If more than an hour passes and you forget to take your Orlistat 120mg dose, this dose should also be skipped. As this medicine doesn’t stay in the system for long, missed doses mean that fat absorption is not blocked as much. It’s best to take Orlistat at roughly the same times each day to help form a habit and ensure consistent effects.

Importantly, Orlistat is not intended as a permanent medication. Over-the-counter Orlistat capsules should only be taken for six months, whereas prescription Orlistat can be taken continuously for up to two years (9). Most people use it for several months, during which they learn to adapt their diet and lifestyle, which helps them maintain their weight loss after stopping the medication.

What are the side effects of Orlistat?

Like any medication, Orlistat has some side effects. Some of the most well-known Orlistat side effects relate directly to how it works in your digestive system. Because Orlistat blocks fat absorption, the undigested fat has to go somewhere—and that usually means passing through your stool.

As a result, you might experience side effects like:

• Oily, loose, or frequent stools
• Urgent or hard-to-control bowel movements
• Gas with oily discharge
• Abdominal discomfort or cramps (10)

These side effects are usually mild and tend to improve as your body adjusts to the medication. However, one way to reduce them is to eat a low-fat diet. By consuming less fat, you’ll have less undigested fat in your digestive tract, reducing these unpleasant symptoms.

This often helps people develop healthier habits, as a lower-fat diet helps them avoid digestive issues—ultimately, Orlistat can support healthy eating by providing an extra incentive to stick with lower-fat foods. This not only aids weight loss but also helps patients form a better relationship with food, potentially making it easier to keep the weight off after stopping the medication.

Is Orlistat safe for everyone?

Orlistat is generally considered a safe and well-tolerated drug—but it isn’t meant for everyone. It is only intended for individuals with pre-existing weight issues, such as being overweight or obese.

On the NHS, you can only get an Orlistat prescription if you are obese. NICE prescribing rules state that doctors can only prescribe Orlistat to people with a body mass index (BMI) of 30 or higher—which is considered obese for most adults (11)—or if those with a BMI of 27 or above and other weight-related conditions, like high blood pressure or diabetes (12).

There are also specific groups of people who should avoid taking Orlistat or use it with caution:

• People with certain health conditions: Orlistat isn’t recommended for those with chronic malabsorption syndrome, cholestasis (a liver condition), or certain types of kidney disease (11)(13). It can make these conditions worse or lead to complications.
• Pregnant or breastfeeding individuals: Taking Orlistat while pregnant doesn’t increase the risk of birth defects (14). However, Orlistat use while pregnant or breastfeeding should be avoided, as it can affect nutrient absorption, which is crucial during these times (13).
• Individuals taking specific medications: Orlistat can interact with some medications, including blood thinners, certain HIV medications, and anti-seizure drugs (10). People on these drugs should try to lose weight via a different route.
• Teens and children: Orlistat is not intended for children with obesity and is only suggested if the child is severely obese or has obesity-related complications (1). Children should never take over-the-counter Orlistat and must be closely monitored by a doctor while taking the drug.

How does Orlistat compare to other weight loss drugs?

Orlistat is just one option in the world of weight loss treatments. While it can be effective, there are alternatives that you might be better suited to, such as weight loss injections.

Here are some popular options all available through Oxford Online Pharmacy and how they compare:

• Mysimba (naltrexone and bupropion): Like Orlistat, Mysimba is a weight loss tablet. It contains two drugs called naltrexone and bupropion. They reduce food hunger and cravings, making Mysimba a practical option for people who struggle with food noise and cravings.
• Wegovy (semaglutide): Wegovy is a weight loss injection that mimics a hormone called GLP-1, which reduces appetite and regulates blood sugar levels. Studies have shown that semaglutide can help people lose up to 15% of their weight, but you must inject it weekly (15).
• Mounjaro (tirzepatide): Mounjaro is another GLP-1 weight loss injection available on prescription. It helps you feel fuller for longer and encourages your body to use your stored fat as energy. It has recently been approved for weight loss in the UK on NHS prescription (16).

Should you try Orlistat for weight loss?

Orlistat isn’t a miracle pill, but for many, losing weight with drugs can help achieve weight loss goals. This weight loss medication might be right for you if you’re looking for a non-prescription weight loss drug (in the case of Alli) or if you prefer to avoid injections.

If you want these weight loss pills, you can order Orlistat online from Oxford Online Pharmacy. Our licensed online pharmacy offers both the over-the-counter 60mg Orlistat (under the brand names Alli and Orlos) and the prescription-strength Orlistat 120mg through our online doctor service.

We also carry various other types of weight loss medication, including weight loss injections like Wegovy (semaglutide) and Mounjaro (tirzepatide). Explore our range of weight loss treatments here.

Citations

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4. Sjöström L, Rissanen A, Andersen T, Boldrin M, Golay A, Koppeschaar HP, et al. Randomised placebo-controlled trial of Orlistat for weight loss and prevention of weight regain in obese patients. European Multicentre Orlistat Study Group. Lancet (London, England) [Internet]. 1998 Jul 18;352(9123):167–72.
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10. Filippatos TD, Derdemezis CS, Gazi IF, Nakou ES, Mikhailidis DP, Elisaf MS. Orlistat-associated adverse effects and drug interactions: a critical review. Drug Safety [Internet]. 2008;31(1):53–65.
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12. BNF. Drugs - Orlistat [Internet]. NICE. ‌
13. Sombra LRS, Anastasopoulou C. Pharmacologic Therapy For Obesity [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2022.
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15. Wilding JPH, Batterham RL, Calanna S. Once-Weekly Semaglutide in Adults with Overweight or Obesity. The New England Journal of Medicine [Internet]. 2021 Feb 10;384(11):989–1002.
16. MHRA authorises diabetes drug Mounjaro (tirzepatide) for weight management and weight loss [Internet]. GOV.UK.