A variety of products are sold in stores as natural weight loss aids, most of which have not been scientifically evaluated. Seven percent of Americans are using over the counter weight loss products, and most are young women.
Because of the Dietary Supplement and Health Education Act (DSHEA) passed by Congress in 1994, weight loss and other supplements are not regulated by the FDA, are not required to demonstrate efficacy for the conditions for which they are promoted, and are not even required to prove that they contain what they claim to contain.
Many of the supplements currently promoted for weight loss have sympathomimetic effects; in other words they are compounds from plants, herbs, or other natural compounds that stimulate the sympathetic nervous system. They carry the same risks as prescription drugs that stimulate the sympathetic nervous system.
One such supplement is the Chinese plant Ma Huang, which contains ephedra, a compound similar to ephedrine, which stimulates the sympathetic nervous system. Ephedra increases heart rate, blood pressure and energy expenditure, stimulating ²-1 and ²-2 adrenergic sympathetic receptors. Ephedra is often combined with caffeine as a weight loss supplement. Ma Huang is also combined with guarana, a Brazilian plant with a high caffeine concentration, and promoted as a weight loss supplement. A recent meta-analysis that pooled the results from several different studies together showed that ephedra containing products result in weight loss of 2 pounds per month, although no information is available for treatment longer than 6 months.
Ephedra is one of the most dangerous over the counter supplements available today. It accounts for the majority of all reports of adverse events for herbs and supplements to the FDA. It is associated with a 2-3 fold increase in psychiatric, autonomic, heart related and gastrointestinal side effects. 87 episodes of heart attack, stroke, seizures, and high blood pressure have been reported to the FDA. It has been associated with several deaths, including a pitcher for the Baltimore Orioles, which led to the unusual (for a supplement) step of the FDA banning it in 1994. The FDA has since revoked the ban.
Hydroxycitric acid is sold under the name garcinia and is promoted for weight loss. It has been shown to inhibit the enzymes that convert compounds into coenzyme A, blocking the storage of energy as fat. The evidence related to its ability to promote weight loss is contradictory. Other products, including psyllium, guar gum, chitosan, chromium, and conjugated linoleic acid showed no effect on weight loss, although they have no major potential toxicities.
The bottom line is that the only natural herbs that might help you lose weight (i.e. Ma Huang) also carries significant potential risk that may be as great as prescription drugs. Sustained changes in diet and exercise that are adopted for life are the best way to lose weight and keep it off.
Showing posts with label FDA. Show all posts
Showing posts with label FDA. Show all posts
Sunday, March 30, 2008
Tuesday, March 25, 2008
Risks of Diet Pills
People often turn to their physician to help them lose weight because it is so difficult. Americans spend billions of dollars every year attempting to lose weight, but their efforts are largely unsuccessful. Some doctors recommend the most natural and difficult path to weight loss, which is to reduce the number of calories consumed and ramp up exercise - and I talk about this method later on in the chapter. However, many patients have tried diets, and want something a bit more powerful to curb their appetite so they eat less, or something that will help them curb cravings and a psychological obsession with food. And these people will keep going to doctors until they find one willing to write a prescription for a diet drug - normally people do not have to search for such a doctor for very long. Alternatively, they will pick up some Ma Huang or another dietary supplement at the drug store, lured by the promise of near magical weight loss.
However, diet drugs generally have not been shown to help people reach or sustain their weight loss goal. Long-term use of diet drugs is associated with some dangers, most importantly the risk of heart attack or other cardiovascular event (even in young people). Another worrisome consequence of diet pills is primary pulmonary hypertension (PPH), a disorder that is typically of unknown cause that is associated with an increase in the pressure of the arteries in the lungs. The primary manifestation of PPH is breathing problems with exercise. The end result of PPH in the absence of a lung transplant is usually death. There is a 6-fold increase in risk of PPH with diet pills, including dexfenfluramine, fenfluramine, diethylpropion, clobenzorek, fenproporek, and phemetrazine. Patient taking diet pills for more than 3 months face a 23-fold increased risk. Although PPH is rare, so that the absolute risk of developing this disorder remains small, the certain lethality of it when it occurs should be cause for concern. At this point we can say that any diet pill that actually affects appetite (i.e. those affecting sympathetic function) should be considered risky.
There are other life threatening side effects with diet pills, notably the dangerous effects of "fen-phen" (fenfluramine-phentermine) on the heart. Although the combination of these pills was never approved by the FDA, by 1996 over 18 million prescriptions a year were being written for this combination of pills as a weight loss treatment. Ultrasound examinations of the heart showed abnormalities of the heart valves in 24 women, five of whom required cardiac surgery for valve repair. This discovery led to the withdrawal of fen-phen from the market.
One of the most commonly prescribed medications for obesity, sibutramine (Meridia), acts on receptors in the brain that take up the neurotransmitters dopamine, norepinephrine, and serotonin back into the neuron. These neurotransmitters are involved in mood as well as appetite regulation. By blocking the reuptake of these neurotransmitters into the neuron, they increase the amount of neurotransmitter that is available in the space between the neurons (the synapse) and therefore increase the effects of these neurotransmitters. It is by this effect that Meridia is felt to have its weight loss properties, although the exact mechanism is not completely understood.
Meridia leads to a 4.45 kg (9 lb.) weight loss after 12 months of treatment (Li et al 2005). Some studies showed up to a 10 kg (22 lb) weight loss with Meridia (Godoy-Matos et al 2005). Unfortunately, weight returns to pre-treatment levels once Meridia is discontinued. Also, multiple studies have not shown evidence that Meridia (or any other weight loss drug for that matter) reduces obesity related death or disease, like heart disease, stroke, and hypertension.
The most common side effect of the drug is palpitations but it also causes increased blood pressure and stroke. Forty-nine cardiac deaths related to Meridia have been reported to the FDA. Administration to pregnant women can lead to fetal abnormalities. This has led to calls for Meridia to be removed from the market.
Orlistat (Xenical) is another drug approved for the treatment of obesity. Orlistat inhibits the lipase enzyme, preventing digestion and absorption of some fats. Orlistat treatment results in 6 pound weight loss that persists for as long as treatment continues (Torgerson et al 2004). 91% of patients get gastrointestinal side effects, versus 65% on placebo. Diarrhea is very common, with less commonly flatulence, bloating, and dyspepsia. Orlistat inhibits absorption of fat-soluble vitamins (A, D, E, K), and may lead to vitamin deficiency, so you should take a vitamin if you are on this drug. Recently a low dose version of orlistat called Alli (pronounced like "ally") has been approved for over the counter use in conjunction with a diet and exercise program.
The bottom line is that diet pills have not been shown to result in sustainable weight loss, and they have significant risks which could be fatal. Therefore I do not recommend their use. The best plan is a sustained change in diet and exercise.
Godoy-Matos A, Carraro L, Vieira A, et al (2005): Treatment of obese adolescents with sibutramine: A randomized, double-blind, controlled study. Journal of Clinical Endocrinology & Metabolism 90:1460-1465.
Li Z, Maglione M, Tu W, et al (2005): Meta-analysis: Pharmacological treatment of obesity. Annals of Internal Medicine 142:532-546.
Torgerson JS, Hauptman J, Boldrin MN, Sjostrom L (2004): Xenical in the prevention of diabetes in obese subjects (XENDOS) study: A randomized study of orlistat as an adjunct to lifestyle changes for the prevention of type 2 diabetes in obese patients. Diabetes Care 27:155-161.
However, diet drugs generally have not been shown to help people reach or sustain their weight loss goal. Long-term use of diet drugs is associated with some dangers, most importantly the risk of heart attack or other cardiovascular event (even in young people). Another worrisome consequence of diet pills is primary pulmonary hypertension (PPH), a disorder that is typically of unknown cause that is associated with an increase in the pressure of the arteries in the lungs. The primary manifestation of PPH is breathing problems with exercise. The end result of PPH in the absence of a lung transplant is usually death. There is a 6-fold increase in risk of PPH with diet pills, including dexfenfluramine, fenfluramine, diethylpropion, clobenzorek, fenproporek, and phemetrazine. Patient taking diet pills for more than 3 months face a 23-fold increased risk. Although PPH is rare, so that the absolute risk of developing this disorder remains small, the certain lethality of it when it occurs should be cause for concern. At this point we can say that any diet pill that actually affects appetite (i.e. those affecting sympathetic function) should be considered risky.
There are other life threatening side effects with diet pills, notably the dangerous effects of "fen-phen" (fenfluramine-phentermine) on the heart. Although the combination of these pills was never approved by the FDA, by 1996 over 18 million prescriptions a year were being written for this combination of pills as a weight loss treatment. Ultrasound examinations of the heart showed abnormalities of the heart valves in 24 women, five of whom required cardiac surgery for valve repair. This discovery led to the withdrawal of fen-phen from the market.
One of the most commonly prescribed medications for obesity, sibutramine (Meridia), acts on receptors in the brain that take up the neurotransmitters dopamine, norepinephrine, and serotonin back into the neuron. These neurotransmitters are involved in mood as well as appetite regulation. By blocking the reuptake of these neurotransmitters into the neuron, they increase the amount of neurotransmitter that is available in the space between the neurons (the synapse) and therefore increase the effects of these neurotransmitters. It is by this effect that Meridia is felt to have its weight loss properties, although the exact mechanism is not completely understood.
Meridia leads to a 4.45 kg (9 lb.) weight loss after 12 months of treatment (Li et al 2005). Some studies showed up to a 10 kg (22 lb) weight loss with Meridia (Godoy-Matos et al 2005). Unfortunately, weight returns to pre-treatment levels once Meridia is discontinued. Also, multiple studies have not shown evidence that Meridia (or any other weight loss drug for that matter) reduces obesity related death or disease, like heart disease, stroke, and hypertension.
The most common side effect of the drug is palpitations but it also causes increased blood pressure and stroke. Forty-nine cardiac deaths related to Meridia have been reported to the FDA. Administration to pregnant women can lead to fetal abnormalities. This has led to calls for Meridia to be removed from the market.
Orlistat (Xenical) is another drug approved for the treatment of obesity. Orlistat inhibits the lipase enzyme, preventing digestion and absorption of some fats. Orlistat treatment results in 6 pound weight loss that persists for as long as treatment continues (Torgerson et al 2004). 91% of patients get gastrointestinal side effects, versus 65% on placebo. Diarrhea is very common, with less commonly flatulence, bloating, and dyspepsia. Orlistat inhibits absorption of fat-soluble vitamins (A, D, E, K), and may lead to vitamin deficiency, so you should take a vitamin if you are on this drug. Recently a low dose version of orlistat called Alli (pronounced like "ally") has been approved for over the counter use in conjunction with a diet and exercise program.
The bottom line is that diet pills have not been shown to result in sustainable weight loss, and they have significant risks which could be fatal. Therefore I do not recommend their use. The best plan is a sustained change in diet and exercise.
Godoy-Matos A, Carraro L, Vieira A, et al (2005): Treatment of obese adolescents with sibutramine: A randomized, double-blind, controlled study. Journal of Clinical Endocrinology & Metabolism 90:1460-1465.
Li Z, Maglione M, Tu W, et al (2005): Meta-analysis: Pharmacological treatment of obesity. Annals of Internal Medicine 142:532-546.
Torgerson JS, Hauptman J, Boldrin MN, Sjostrom L (2004): Xenical in the prevention of diabetes in obese subjects (XENDOS) study: A randomized study of orlistat as an adjunct to lifestyle changes for the prevention of type 2 diabetes in obese patients. Diabetes Care 27:155-161.
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