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Orlistat: A New Option in Weight Control


Michelle Osborn

Orlistat is a lipase-inhibitor drug designed to help obese individuals lose and maintain their body weight. The drug in combination with a healthy low-fat diet and exercise can help in the treatment of obesity. Reducing fat intake is critical when attempting to reduce body fat. Orlistat reduces body fat by increasing the amount of fat passed through the body. The drug has already been approved in Europe and is expected to be approved by the FDA in the US in 1999.There have been scientific studies which support the effectiveness and low risks of Orlistat. Diet and exercise should be stressed in all attempts at weight loss, yet it seems Orlistat may be a helpful addition to the weight loss program for obese patients.

Purpose of Treatment:

Orlistat is a drug that is geared towards helping obese patients who have a bodymass index of 30 or over. It is not meant to replace a healthy lifestyle, instead it is meant to be an additional supplement with exercise and a healthy diet (Brooks 835). Orlistat is designed to prevent the body from breaking down and absorbing fat. In addition to reducing body fat Orlistat also reduces highblood pressure, high cholesterol, and high blood sugar ( Some of the unpleasant side effects of Orlistat can lead to behavioral changes as well. Orlistat causes a learned aversion response to over indulging in fatty foods and thus decreases the amount of calories and fat consumed by the body (

How it Works:

The drug does not effect the brain as do other weight loss drugs such as Redux and Phen-fen and Meridia. Orlistat is a lipase inhibitor, meaning it interferes with fat absorption. Dietary fats are large molecules which are broken down by enzymes known as lipases and then absorbed into the body. These digestive enzymes are produced by the liver and pancreas whenever food is injected into the intestine. The enzymes aid in the absorption of nutrients from the food. Orlistat has been designed to act as an inhibitor of two enzymes: pancreatic and gastric lipases. This action reduces the hydrolysis of dietary triglycerides and prevents the absorption of free fatty acids and cholesterol (David 1997). One digestive fluid contains pancreatic lipase, which absorbs fat. Orlistat inhibits this lipase causing less fat to be absorbed into the bloodstream. The drug must be consumed right before or within an hour of consuming a meal. After the drug is taken approximately 30% of the unabsorbed fat passes through the intestines and leaves the body through the feces (Myers, 1999).  Only fat is blocked. Protein and carbohydrates and most vitamins and minerals, with the exception of fat soluble vitamins, are absorbed (


Is it Effective ?:


Orlistat appears to be very effective when it comes to weight loss. So far all of the studies on Orlistat indicate that the individuals receiving Orlistat compared to the placebo groups have lost significantly more weight. However the negative side effects, such as loose stools, an increased frequency and urgency of defecation, and abdominal pain cause many patients to go off the drug (David, 1997). Therefore the side effects may eventually cause the individual to stop taking the drug. The side effects are a result of eating too much fat (Williamson, 1999). Therefore, the side effects could also lead the patient to alter their behavior, and thus consume less fat. Depending on the individual the negative side effects could work in a positive or negative direction (


Evidence to Support Claims:


The most recent and extensive study was published by JAMA and conducted by Dr. Michael Davidson (Davidson et. al, 1999). The question they were asking was whether or not Orlistat in combination with a healthy diet and exercise lead to an increase in weight loss compared to a placebo plus healthy diet and exercise. --The methods of the study included subjects from over 18 clinical research centers in the US. The criteria required the patient to be over 18 years old, body mass index to be over 30, adequate contraception in women, and absence of weight loss in the previous three months. The experiment was double-blind, randomized, placebo-controlled, and evaluated over a two year period. Subjects had a controlled diet and there was a requirement of energy expenditure per week.   Part of the program also included behavior modification. Orlistat was given to some patients in 60 mg. and to others in 120 mg. three times a day --There were a total of 403 subjects out of 1187 enrolled subjects who completed the two years of the study. The orlistat group lost weight more rapidly and they lost more weight as well. Over 65% of the patients on Orlistat lost over5% of their initial body weight compared with the 43% of placebo treated patients in the first year. The second year the 39% of the orlistat group lost about 10%of their initial body weight compared to the 25% of the placebo group. Weight loss was well maintained during the first year and those who stayed on orlistat during the second year maintained their weight. However, those who were on orlistat the first year and placed in the placebo group the second year regained most of their weight. To view the results in closer detail click on the hypertext link at directing you to JAMA (


Side Effects and Who Should and Should Not Take Orlistat:


Negative side effects of orlistat include loose oily or fatty stools, possible uncontrolled bowl movements, flatulence with discharge, and abdominal pain.  Levels of fat-soluble vitamins and betacarotene decreased slightly when taking orlistat, but can be reversed with vitamin supplements (Davidson et. al, 1999).  Positive side effects of orlistat include lowering blood pressure, improvements in LDL-C (the good cholesterol), and slight improvements of cholesterol levels altogether. However, this could be attributed to greater increase in weight loss (Davidson et al., 1999).

Individuals who should NOT take this drug include those who have binge eating disorder, bulimia nervosa, and malabsorption syndromes. They would have gastrointestinal distresses and severe pain and fecal incontinence (Myers, 1999).


FDA Approval in the US:


Europe approved orlistat in July of 1998 (media release July 31, The US FDA has asked the pharmaceutical company Hoffman-LaRoche, who is seeking approval for the drug, in order go gain more time to submit further analyses on data in concern to the link between orlistat and breast cancer. The FDA committee supported the drug and viewed it as effective and safe in May of 1998. However, Roche withdrew its application in August of 1997 to further look into the breast cancer connection. Roche is of the opinion that there is no connection between orlistat and breast cancer, yet there were a limited number of cases in the clinical trials where a very few number of cases occurred more in the orlistat group than in the placebo group. Roche commented that breast cancer takes years to develop and would not have developed in these women in the short span of time that they were taking orlistat. However, they wish to eliminate all suspensions and are further checking into the possibility of the connection. If all goes well it is thought that orlistat could be approved by the FDA in 1999 (media release Aug. 28,


Other Web Sites and What Info They are Presenting and Why?:


The majority of web sites on Orlistat range from those that include observations and studies published in medical journals to web sites on news pages (MSNBC, ABC,etc...). These are mostly straight forward and usually objective. They present the facts and are attempting to present the public with the most current and non-biased information. There is a web site of Roche's laboratories which could possibly be biased, however they are only allowed to give certain information to the public. Certain sites on their page, such as obesity drugs, can not be accessed without a password. There are sites which have been developed in the UK which are extremely warped. They offer to sell orlistat over the Internet. This could be extremely dangerous and is not recommended. In order to take orlistat one should be over 30 on the body mass index and should consult their doctor.


Orlistat appears to be an effective drug and has several positive and negative side effects. If taken the drug should be accompanied with a low-fat diet and exercise. You should also consult your doctor before taking this medication. The brand name of the drug is Xenical and if you are interested in finding out more about side effects and who should and should not take the drug access the hypertext links below.


Works Cited


Brooks, Alexander. Obesity drug is licensed in the UK. British Medical Journal.317 (1998): 835.

David, Marvin and Dennis Feller. Advances and retreats in the pharmacotherapy of obesity. Drug Topics. 141 (1997): 114-123.

Davidson, Michael and Jonathan Hauptman, Mario DiGirolamo, and John Foreytet etal. Weight control and risk factor reduction in obese subjects treated for 2years with orlistat: A randomized controlled trial. JAMA. 281 (1999): 235-241.

Myers, Michael. Orlistat- a Promising Medication for Obesity Treatment and Weight Maintenance. Online. Server. Internet. 11 Feb. 1999. Available htttp://

Williamson, David. Pharmacotherapy for obesity. JAMA. 281 (1999): 278.

Orlistat and Obesity. 1999. Online. Server. Internet. 11 Feb. 1999. Available

Roche Media Release. 1998. Online. Server. Internet. 11Feb. 1999. Available

1997. Online. Server. Internet. 14 Feb. 1999. Available

U.K. Yes. Online. Server. Internet. 11 Feb. 1999. Available


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