Fat blockers

What are fat blockers

Fat blockers are drugs that are designed to aid weight loss. They do not work like the appetite suppressants in the brain, but in the gastrointestinal tract. There they inhibit the enzyme lipase, which normally breaks down the ingested fats (triglycerides) into small components. By inhibiting the enzyme, it is no longer possible to break down the fats.

However, since the fats can only be absorbed by the body in split form, fat blockers reduce the absorption and absorption rate of fats ingested with food by around 35%. Fat blockers do not change anything in the appetite, it stays the same or even increases.

Which fat blockers are there?

The only "real" fat blocker is the active ingredient orlistat. It is offered in different dosages and therefore has different trade names:

  • Xenical®
  • Orlistat ®
  • Alli Orlistat®

The drugs that advertise being fat blockers include a product known under the trade name Formoline ®.

Read more on this topic at: Diet pills


Xenical contains the active ingredient orlistat in the highest dosage available on the pharmaceutical market. The drug contains 120 mg of orlistat.
3 capsules should be swallowed whole with a little water with the main meals.

It should be used in conjunction with a low-calorie diet with a BMI of at least 30 kg / m2 or overweight with risk factors such as diabetes mellitus from a BMI of at least 28 kg / m2.

Xenical comes in packs of 42 or 84 pieces.

The drug requires a prescription, but only a private prescription can be issued, not a health insurance prescription, so in most cases the costs are to be borne by the patient himself.

Read more on the topic: Orlistat

Do fat blockers require a prescription?

The only actual fat blocker currently available on the market with the active ingredient orlistat does not require a prescription in low doses (60 mg).

In higher doses (120 mg), however, it is only available on prescription. However, no prescription can be issued, as the costs must be borne by the patient himself. Therefore, only a private prescription is issued.

Indications for fat blockers

According to the instructions for use, the fat blocker Orlistat is indicated from a body mass index of 30 kg / m2 or a BMI of 28 kg / m2 if there are also risk factors.
These risk factors include, for example, diabetes mellitus or lipid metabolism disorders.

It should only be used with a simultaneous change in diet. This should include a low-calorie, low-fat diet.

Read more on the subject at: Lose weight by changing your diet

Can you lose weight with fat blockers without diet and exercise?

No. The principle of fat blockers is the combination of a lower-fat, healthier diet and supportive help from a drug.
Fat blockers can only inhibit a certain amount of fat absorption. So if you continue to consume too much fat, a fat blocker will not be enough to achieve permanent weight loss.

Whether exercise is always necessary to lose weight is certainly a controversial topic. Especially for patients with a BMI over 30 kg / m2, light endurance sports should show relatively quick success and is therefore recommended.
Not only for losing weight but also for basic physical fitness.

Read more about this: Losing weight without exercise and diet - is that possible? Losing weight without hunger

What success can be expected from taking fat blockers?

As mentioned briefly above, studies have shown the effectiveness of the fat blocker orlistat in comparison with a dummy drug (placebo). About 20% of patients who regularly took orlistat and followed a diet were able to reduce their weight by more than 10%.

However, there is still a risk of the yo-yo effect after stopping treatment with Orlistat. However, this was also compared with a placebo and it was found that patients who had taken orlistat gained 3.2 kg instead of 5.6 kg (placebo).

The extent of the weight loss depends on the initial weight and diet compliance. And of course whether there is also regular physical activity.

How the fat blocker works

Orlistat inhibits the enzyme lipase in the gastrointestinal tract. Lipase is responsible for breaking down the fats (triglycerides) ingested with food into free fatty acids and monoglycerides.
As a result of the inhibition, the lipase can no longer carry out this cleavage. The fats ingested with food can only get into the blood in split form via the intestinal wall and thus meet their further use, for example for fat storage. An inhibition of the lipase leads to a decreased fat absorption of the body.

By using fat blockers, about 1/3 of the fats ingested with food should be absorbed less. In most cases this results in a reduction in body weight.

Studies have shown that over a year, the average weight loss in patients who took orlistat and dieted was greater than that of patients who dieted and took a placebo, a dummy drug.
The proportion of patients who lost more than 10% of their body weight during the therapy was 21% (in the placebo group only 9%).

Side effects of fat blockers

The unwanted effects of Orlistat include abdominal pain, increased stool, fecal incontinence, gas, pain in the rectum, discomfort in teeth and gums, headache, fatigue, anxiety, urinary tract infections (bladder infections), kidney damage due to deposits of crystals, infections of the respiratory tract, flu and menstrual cramps.

Fat Blocker Interactions

Orlistat can inhibit the absorption of the fat-soluble vitamins A, D, E and K. This is because these vitamins can only be absorbed if they are surrounded by a layer of fat-soluble and water-soluble substances, the so-called micelles.
Since fat blockers inhibit lipase, they also inhibit the breakdown of dietary fats and the formation of micelles can be reduced, which affects the absorption of vitamins.

The drug should also not be taken with acarbose, a drug used to treat diabetes mellitus. These two drugs can interfere with each other in their effects.

Orlistat can lower the blood level of the heart drug amiodarone, so the attending physician / cardiologist should be consulted before taking orlistat.

It can also affect the way blood thinners (anticoagulants) work. The blood values ​​should therefore be checked regularly, especially at the beginning of therapy.

Orlistat should not be taken with the immunosuppressant ciclospoprin A as it can make it less effective.

In addition, orlistat and the thyroid hormone L-thyorxine should not be taken at the same time but with a sufficient interval; the thyroxine dose may have to be adjusted.

There is also some evidence that orlistat affects the anti-epileptic drugs valproate and lamotrigine, which can lead to seizures.

Fat blockers and alcohol - are they compatible?

In principle, there are no contraindications to alcohol consumption when taking orlistat.

However, since a hypocaloric (i.e. reduced-calorie) diet is recommended when taking Orlistat and alcohol contains a relatively high number of calories, alcohol consumption should be significantly reduced.

When should I not take fat blockers?

The contraindications include known hypersensitivity reactions to the ingredients, a build-up of bile (cholestasis), for example in the context of gallstone disease, or known food intake or absorption disorders.

Breastfeeding is also considered a contraindication to taking fat blockers such as orlistat.


One capsule of Orlistat 120 mg should be taken 3 times a day immediately before, during or within one hour after the main meal.

If a meal is missed or if it is fat-free, no capsule should be taken.
As early as 24-48 hours after the start of therapy, increased fat excretion occurs with the stool.

Price of fat blockers

The price differs for the various preparations. The prescription Xenical is available in 2 different pack sizes, each 120 mg per capsule: 42 or 84 pieces. 42 capsules currently cost 46 euros in a cheap online pharmacy. The daily therapy costs are therefore 3.30 euros.
84 capsules cost just under 59 euros, which is significantly less. The daily therapy costs here amount to 2.10 euros.

Orlistat Hexal is also available in packs of 42 or 84 pieces.
Each capsule contains 60 mg, the capsules can be purchased without a prescription. A package of 42 pieces costs just under 20 euros, so a recommendation of 3 x 120 mg per day costs 2.80 euros. A pack of 84 capsules costs just under 4 euros more, the daily therapy costs are around 1.70 euros.

Alternatives to fat blockers

Formoline is not a real fat blocker. It contains polyglucosamine. This substance is of vegetable nature and is supposed to bind nutritional fats in the gastrointestinal tract so that these are excreted undigested.

When taking Formoline, as with Orlistat, a low-fat diet with 60-80 g fat per day is recommended. It can be taken as an alternative to the fat blocker orlistat.
Formoline is available from pharmacies without a prescription.

In addition to fat blockers, there is also the group of appetite suppressants. They work in the CNS and inhibit the hunger center there or stimulate the satiety center.
Most of these active ingredients have caused some serious side effects so that there is currently no recommended active ingredient on the market that acts as a pure appetite suppressant.

The best and most natural alternative to fat blockers is of course a healthy, balanced diet and regular exercise.

Use during pregnancy and breastfeeding

There are insufficient studies on the use of orlistat during pregnancy and breastfeeding so that it is currently not recommended to use it during this period.
The use of products such as Formoline is also not recommended during pregnancy and breastfeeding.

Effectiveness of the pill when taking fat blockers

Basically the fat blocker Orlistat has no effect on the effectiveness of the pill.

However, diarrhea and vomiting can occur as a side effect of orlistat. In this situation, the effectiveness of the pill is no longer guaranteed and an alternative method of contraception should be used.

When taking Formoline, an interval of 4 hours should be observed before the pill is taken, otherwise the effectiveness of the pill is not guaranteed.