Index - Click on the section you wish to read
Phen/fen is a popular drug treatment for obesity and binge eating disorders. Two medications named phentermine (phen) and fenfluramine (fen) are taken together in order to work in a balanced fashion on two of the body's neurotransmitters. Phentermine blocks the absorption of a neurotransmitter called dopamine. Dopomine is a stimulant that raises the body's temperature and increases metabolic rate. The effect of this blockage is a decreased appetite and an increase in metabolic rate (http://www.ulink.net/-dtison/). Fenfluramine works on the nuerotransmitter called serotonin. Increased levels of serotonin make someone feel calm and full. Fenfluramine increases the levels of serotonin available for the body to use which tricks the body into feeling fuller and decreasing one's appetite. 'The strength of the fen/phen protocol is that it permits regulation of each nuerotransmitter independently. Were there to be an insuff iciency of dopomine, the phentermine (phen) dose can be increased; an excess of serotonin, the fenfluramine (fen) dose is tapered' (http://www.fenphen.com/philosophy.html).
Phen/fen regulates the body's natural chemistry and keeps it in balance. By doing so, 'it eliminates psychological cravings for food, cuts down excessive hunger, and reduces depression-related ailments that result in eating disorders such as bulimia and anorexia" (http://www.fenphen.com/hope.html).
The internet contains hundreds of web sites full of information on phen/fen along with advertisements for the treatment. But, it should be understood that "they are not 'fat pills,' as has been mentioned in some of the news media; they do not absorb fat or block fat from entering the system. They do not alter one's genetic make-up, which can be a contributing cause of obesity' (http://kingsfans.com/wein.htm)
Phen/fen treatments are meant for people who have a BMI (body mass index) of 28 or higher or are at least 20% over their ideal body weight (Anonymous, 1996). However, cases have been documented where people have been given the treatment who did not fit that criteria. For example, Teagan Clive (1997) reported in Joe Weider's Muscle and Fitness that she received the treatment although she was only 8% over her ideal body weight. The bottom line is that these companies are selling a product to make money, and they are not too concerned with people's health.
To see if you qualify for treatment, check out the Medical Weight Management
web site (http://www.phenfen.com).
The site has a place to fill in your measurements so that you can calculate
your body mass index and find out if you can sign up. (However, anyone
can lie about their measurements and receive the treatment.) The site seems
like a marketing tool to convince people to sign up for the treatment.
Thus, everyone needs to be a smart consumer when reading the information
on the web!
The information on the Internet is contradictory on the issue of diet and exercise while using phen/fen medication. In order to lose weight faster and keep the weight off, it is suggested that one adopt an exercise routine while taking the medication. Also, sometimes people develop tolerance to phen/fen and the medication no longer works as well. Thus, a diet and exercise program is needed to ensure that one will still keep off the weight. (http://www.ulink.net/~dtison/faq.htm). Patients are also encouraged to increase their activity level by taking the stairs at work or riding their bike instead of a driving a car. 'The emphasis is on a consistent exercise program that is enjoyable and that can be realistically followed' (http://kingsfans.com/wein.htm). Also, it is highly recommended that a patient meet with a nutritionist in order to learn how to monitor their personal eating habits and make changes that will last a lifetime.
But, not all information on the web agrees with the diet and exercise
recommendations. For example, one site states 'Phen-Fen and Redux help
you eat less of whatever it is you are eating so a regimented diet is not
Another site claims that diet is not necessary because it will lower
one's metabolism and 'patients in the protocol unconsciously choose healthy
and well balanced foods' (http://www.fenphen.com/faq-3.html).
In other words, the claim is that one's eating habits will miraculously
change while using the pills without any effort on the consumer's part.
The same site claims that one does not need to engage in exercise while
using phen/fen because 'exercise is not needed either to lose weight or
feel good. The 'runner's high' occurs due to an endorphin-induced dopamine
Overall, one can find a yes and no answer to the question of the necessity
of diet and exercise in combination with the,treatment. One must use good
judgment and be realistic about their personal weight loss goals. But,
one thing is for certain... diet and exercise can only help!
There are many conflicting messages about the presence of side effects from phen/fen treatment. One University of Chicago site reports that the common side effects from treatment are drowsiness, diarrhea and dry mouth which tend to only lost a couple of weeks. However, the site warns that primary pulmonary hypertension is an effect that should be a cause for worry. It is a dangerous cardiovascular condition that can be fatal; there are 18 cases per 1,000,000 users reported every year. (http://uhs.bsd.uchicago.edu:80/-bhsiung/tips/probs.html).
Another Weintraub study site reports that dry mouth can last for months
and other intestinal effects such as nausea, a metallic taste, constipation,
diarrhea, and abdominal pain can last for weeks. Also, drowsiness, disturbed
sleep, dizziness, nervousness, and depression usually occur up to six weeks
The same site also warns people against seeking the treatment if they
suffer from migraine headaches or clinical depression, People need to be
monitored by a physician during treatment because complications can occur
when phen/fen is combined with high blood pressure and diabetes. However,
one fen/phen web site claims that one should not caution against using
phen/fen if one has high blood pressure, migraines, diabetes, or heart
disease. 'The rationale behind the fenfluramine and phentermine combination
is that medication cancels the side-effects known to result from the use
of the other. There are practically no known medical conditions' (http://fenphen.com/faq-5.html).
However, later the some site states that 'potential side effects could
be serious, however, if these medications are not properly balanced' (http://fenphen.com/faq-5.htmi).
But, no specific examples are sited. The only warning given is against
taking antidepressant medication while using phen/fen. Overall, the research
on the internet is contradictory about the side effects while using phen/fen.
Thus, one should definitely consult a physician before signing starting
The first hype about Phen/fen started in May of 1992 when Weintraub first published a study on the use of fenfluramine and phentermine in conjunction with behavior modification, dieting, and exercise as a weight loss strategy. The 34 week study used 121 people and randomly divided them into two groups. One group took the medication and the other group took pills that were placebos (fakes). All participants were between the ages of 18 and 60 and were at least 30-80% over their ideal body weight. At the conclusion of the study, the group who used the medication lost an average of 32 pounds while the placebo group only lost an average of 9 pounds. However, it is important to note that all participants ate a healthy diet and exercised regularly while on the program. Weintraub (I992) continued follow up studies after the initial study with the same people. The experimenters took all subjects off the medication during weeks 190 to 210. They found that during those 20 weeks almost all of the subjects had gained back the weight they lost. Thus, it was difficult for subjects to keep off the weight without the aid of Phen/Fen (Weintraub, 1992; http://kingsfans.com/wein.htm).
Carrell (I997) reviewed studies on several weight loss drugs including phentermine/fenfluramine and concluded that the combo can help people initially lose weight, but the weight does not always stay off once someone is off the medication. Also, the long-term results and side effects are still in question,
Atkinson and Hubbard (1994) reviewed a National Institute of Health workshop on pharmacological treatment of obesity. After reviewing the literature presented, they concluded that obesity drugs such as phen/fen may produce significant results in weight reduction over a stretch of time; however, drugs should be used in combination with other behavior such as healthy eating and exercise. Also, they suggest that future research examine how different types of obesity or variables such as race, sex, age react to different drug treatments.
Goldstein and Potvin (1994) reviewed several studies that used fenfluramine and phentermine for weight loss, They concluded that there were often terrible side effects involved with treatment such as insomnia, nausea, diarrhea, dizziness, depression, abnormal heart rate, and vomiting. Overall, most people gained all their weight back once they stopped taking the drug treatment.
Similar to the information on the Internet that is trying to sell phen/fen
treatment, the scientific literature is conflicting and contradictory.
Overall, the literature suggests that a person cannot rely on drugs such
as phen/fen alone for weight reduction. One must change one's behavior
to include exercise and healthy eating habits in order to keep the weight
off. As one site so eloquently states, 'Exercise, changing what you eat,
and behavior modification are integral parts of the program and must be
actively pursued. The medications alone are not the sole answer, though
they will help most people who follow the entire program. Good Luck!' (http://kingsfans.com/wein.htm).
Anonymous,(1996). Trackingthe'fen-phen'drugtrend. The Physician and
Atkinson, Richard L. and Hubbard, Van S. (1994) Report on the NIH Workshop
on Pharmacologic Treatment of Obesity. The American Journal of Clinical
Nutrition, 60, 153-160.
Carrell, Steve (I 997) Don't Expect Long-Term Weight Loss Form Obesity
Drugs. Drug Topics, 141, 42-43.
Clive, Teagan (1997) Who Gets Phen-Fen and Why. Joe Wieder's Muscle
and Fitness, 58, 102.
Goldstein, David J. and Potvin, Janet H. (1 994). Long-term Weight Loss: The Effect of Pharmacologic Agents. The American Journal of Clinical Nutrition, 60, 647-663.
Weintraub, M. (I992). Long-term Weight Control: The National Heart, Lung, and Blood Institute Funded Multimodal Intervention Study. Clinical Pharmacology and Therapeutics, 51, 581-646.
Psychology DepartmentThe Health Psychology Home Page is produced and maintained by David Schlundt, PhD.
Vanderbilt Homepage | Introduction to Vanderbilt | Admissions | Colleges & Schools | Research Centers | News & Media Information | People at Vanderbilt | Libraries | Administrative Departments | Medical
|Return to the Health Psychology Home Page|
|Send E-mail comments or questions to Dr. Schlundt|