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Appetite suppressants


Related terms
Author information
Guidelines for obesity treatment
Safety of appetite suppressants
Gastric bypass surgery background
Risks of gastric bypass surgery
Other types of weight loss surgery

Related Terms
  • Adipex-P®, adjustable gastric banding, biliopancreatic diversion, bitter orange, BMI, body mass index, dexfenfluramine, dietary supplements, diethylpropion, Dietrine Carb Blocker with Phase 2®, ephedra, ephedrine, ephedrinum, fenfluramine, gastric bypass surgery, hoodia, jaw wiring, liposuction, ma huang, Meridia®, obesity treatment, orlistat, phentermine, phenylpropanolamine, Pondimin®, PPA, redux, sibutramine, Tenuate®, vertical banded gastroplasty, waist circumference, weight loss, weight loss drugs, weight loss supplements, Xenical®.

  • Appetite suppressants are agents that promote weight loss by decreasing appetite or increasing the sensation of fullness. About one-quarter of the U.S. population can be considered obese (BMI of >20). Four million of these people may be classified as morbidly obese (BMI of >40). Obesity is associated with increased risk of hypertension, type 2 diabetes and heart disease. The use of appetite suppressant medications to treat obesity in combination with physical activity and diet modification is often recommended to lose and maintain weight successfully over the long term.

Theory / Evidence
  • Several prescription medications are currently approved for treatment of obesity. In general, the effects of these medications are modest, leading to an average initial weight loss of between 5 and 22 pounds; though studies show that weight returns after cessation of the drugs. There is considerable individual difference in response to these medications; some people experience greater weight loss than others.
  • Short-term use of appetite suppressant medications has been shown to modestly reduce health risks for obese individuals. Studies have found that these medications can lower blood pressure, blood cholesterol, blood fats (triglycerides) and decrease insulin resistance (the body's inability to utilize blood sugar). Long-term studies need to be conducted to determine if weight loss assisted by appetite suppressant medications can improve health long-term.
  • Weight loss tends to be greatest during the first few weeks or months of treatment, leveling off after about six months. Research suggests that if a patient does not lose at least four pounds during the first four weeks on a particular medication, that medication is unlikely to be effective over the long run.
  • Short-term use (few weeks to few months): Examples include diethylpropion (Tenuate®), and phentermine (Adipex-P®).
  • The mechanism of action of diethylpropion and phentermine appears to be secondary to CNS (central nervous system) effects, specifically stimulation of the hypothalamus to release catecholamines into the central nervous system. Appetite-suppressing effects are mediated via norepinephrine and dopamine metabolism.
  • Long-term use (up to one year or more): Orlistat (Xenical®) is the first prescription treatment for obesity that does not act as an appetite suppressant. It works by interfering with the action of gastrointestinal (GI) lipase in the GI tract. As a result of this mechanism of action, 30% of ingested dietary fat is not absorbed.
  • Another prescription weight-loss drug, sibutramine (Meridia®), was removed from the U.S. market in 2010 due to an increased risk of heart problems.
  • OTC (over-the-counter): It is believed that the "P57" molecule in hoodia mimics the effect of glucose has on the brain, telling part of the brain (the hypothalamus) that the person feels full. Consequently, the person has no desire to eat. However current available evidence on hoodia's effectiveness and safety is lacking.
  • Dietrine Carb Blocker with Phase 2®: An ingredient extracted from white kidney beans is thought to neutralize the digestive enzyme alpha amylase before it can convert starch into glucose and then fat.

Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. American Society for Bariatric Surgery. Rationale for the Surgical Treatment of Obesity. Updated April 6, 1998.
  2. Gastric bypass: Is this weight-loss surgery for you? 17 May 2006.
  3. Gastric Surgery for Severe Obesity. National Institute of Diabetes and Digestive and Kidney Diseases. NIH Publication No. 96-4006, April 1996.
  4. Ioannides-Demos L, Proietto J, et al. Safety of drug therapies used for weight loss and treatment of obesity. Drug Saf. 2006;29(4):277-302.
  5. Kral, J.G. Surgical Treatment of Obesity. In Handbook of Obesity, ed. Bray, G.A., Bouchard, C., James, W.P.T. New York. Marcel Dekker, Inc., 1998.
  6. National Heart, Lung, and Blood Institute. Clinical Guidelines on the Identification, Evaluation, and Treatment of Obesity in Adults: The Evidence Report. NHLBI Obesity Education Initiative Expert Panel on the Identification, Evaluation, and Treatment of Obesity in Adults. Washington, DC: U.S. Department of Health and Human Services, 1998.
  7. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) of the National Institutes of Health (NIH). Prescription Medications for the Treatment of Obesity, MSI-WCIN019, Weight-control information network. 2001.
  8. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) of the National Institutes of Health (NIH). Questions About Appetite Suppressant Medication Treatment, MSI-WCIN020, Weight-control information network. 2001.
  9. Obesity Surgery. 17 May 2006.
  10. Shape Up America! American Obesity Association. Guidance for the Treatment of Adult Obesity. Bethesda, MD, revised 1998.
  11. Shekelle P, Morton, S., Maglione M, et al. Ephedra and Ephedrine for Weight Loss and Athletic Performance Enhancement: Clinical Efficacy and Side Effects. Evidence Report/Technology Assessment No. 76, Southern California Evidence-based Practice Center, RAND.
  12. U. S. Food and Drug Administration. FDA Approves Orlistat for Obesity, Food and Drug Administration FDA Talk Paper, April 26, 1999.

Guidelines for obesity treatment
  • Assessment of weight involves evaluating body mass index, waist circumference and the patient's risk factors.
  • BMI=weight (kg)/[height (m)]2.
  • Overweight is defined as a BMI of 25-29.9 kg/m2.
  • Obesity is defined as a BMI of ?30 kg/m2.
  • Waist circumference for men >40 inches or women >35 inches indicates an increased risk for those with a BMI of 25-34.9.
  • Coronary heart disease or other atherosclerotic diseases, type 2 diabetes and sleep apnea are factors associated with a very high risk of developing disease complications and mortality.
  • Weight loss is recommended for those who are obese (BMI ?30kg/m2) and for those who are classified as overweight (BMI of 25-29.9kg/m2) or have a high waist circumference and two or more risk factors.

Safety of appetite suppressants
  • Ephedrine: Since March 2004, the sale of all products containing ephedra in the United States has been banned. Other names of ephedrine are ephedra, ephedrinum, and ma huang.
  • A study, published in the February 2003 issue of the Annals of Internal Medicine, found that ephedra supplements made up only 1% of all dietary supplement sales, but accounted for 64% of adverse effects associated with dietary supplements.
  • A case-control study, published in a 1993 issue of Neurology, concluded that the rate of hemorrhagic (bleeding) strokes among ephedra-users was significantly higher than among nonusers, for people taking doses above 32mg a day. According to the US Food and Drug Administration (FDA), many ephedra-containing dietary supplement labels recommend that users take up to 100mg of ephedra daily.
  • Fenfluramine (Pondimin®) and dexfenfluramine (Redux®): These two medications were voluntarily removed from the market in 1997. Both were shown to be associated with a rare, but very serious, and potentially fatal disorder known as primary pulmonary hypertension (PPH), a disease of the lungs. Forty-five percent of patients with PPH die within four years of diagnosis.
  • Phenylpropanolamine (PPA): PPA is a synthetic sympathomimetic amine structurally similar to pressor amines (e.g., epinephrine, phenylephrine, and ephedrine) and central nervous system stimulants (e.g., ephedrine, amphetamine). It is a common ingredient in cough-cold remedies and appetite suppressants. A study reports that taking PPA increases the risk of hemorrhagic stroke (bleeding into the brain or into tissue surrounding the brain) in women. Men may also be at risk, but no data are available. Although the risk of hemorrhagic stroke is very low, the FDA recommends that consumers should not use any products that contain PPA, and manufacturers should reformulate or recall all medications containing PPA.
  • General safety concerns: Most side effects of the medications that are approved by FDA are mild and diminish as treatment continues. Rarely, serious and even fatal outcomes have been reported. Medications that affect catecholamine levels, such as phentermine and dietylpropion, may cause symptoms of sleeplessness or nervousness.

Gastric bypass surgery background
  • Roux-en-Y gastric bypass surgery is the most common weight loss surgery which uses staples to restrict food intake. The staples are surgically placed near the top of the stomach to section off a small portion that is often called a stomach pouch. Then, a Y-shaped section of the small intestine is attached to the pouch to allow food to bypass the lower stomach, the duodenum (the first segment of the small intestine), and the first portion of the jejunum (the second segment of the small intestine). Because part of the digestive system is "bypassed", absorption of food and nutrients is decreased.
  • This surgery is often performed in those who have a BMI ?40 (extremely obese) or BMI between 35 to 39.9 and with weight-related health problems, such as diabetes or high blood pressure.
  • Surgical candidates go through an extensive screening process. Not everyone who meets the criteria for the surgery is psychologically or medically ready for the surgical procedure. A team of professionals, including a physician, dietitian, psychologist and surgeon, evaluate whether the surgery is appropriate. Following surgery, physical, nutritional and metabolic counseling are given to prevent nutritional deficiencies. Lifelong use of nutritional supplements such as multivitamins, vitamin B12, vitamin D and calcium is recommended.
  • Researchers have found greater weight loss in gastric bypass (an average of 93.3 pounds) compared to gastroplasty ( an average of 67 pounds) after one year. Over two years, gastric bypass surgery patients have been shown to lose two-thirds of excess weight. The success rate for weight loss for Roux-en-Y gastric bypass surgery is 68 to 72% of excess body weight over a three-year period, and 75% for biliopancreatic diversion. After five years, the average excess weight loss from gastric bypass surgery ranges from 48 to 74%.
  • The improvements observed in type 2 diabetes, high blood pressure and high blood cholesterol may significantly decrease the risk of cardiovascular events in individuals who have undergone gastric bypass surgery compared with those treated through other means. Gastric bypass surgery has also shown to improve mobility and quality of life for people who are severely overweight.

Risks of gastric bypass surgery
  • A risk of death has been associated with gastric bypass surgery. The risk varies depending on age, general health and other medical conditions. Patients should review the risks of gastric bypass surgery with a doctor.
  • Blood clots in the legs are more likely to occur in very overweight people. Blood clots can be dangerous. In some cases, they travel to the lungs and lodge in the lungs' arteries, causing a pulmonary embolism - a serious condition that damages lung tissue and can lead to death. Walking and using leg wraps that apply intermittent pressure to the leg can help reduce this risk of blood clots in the legs.
  • Leaking of the stomach contents into the body cavity at a staple line has occurred and can be treated with antibiotics. Most cases heal with time. Sometimes, the leak can be serious enough to require emergency surgery.
  • Excess weight places extra stress on the chest cavity and lungs. This means a higher risk of developing pneumonia after the surgery.
  • Narrowing of the opening between the stomach and small intestine has occurred. This rare complication may require either an outpatient procedure to pass a tube through the patient's mouth to widen (dilate) the narrowed opening or corrective surgery.
  • Gastric bypass can also cause dumping syndrome, a condition where stomach contents move too quickly through the small intestine causing nausea, vomiting, diarrhea, dizziness and sweating.
  • Other common complications include vitamin and mineral deficiency, dehydration, gallstones, bleeding stomach ulcer, hernia at the incision site and intolerance to certain foods.

Other types of weight loss surgery
  • Adjustable gastric banding: The surgeon uses an inflatable band to partition the stomach into two parts. The surgeon then wraps the band around the upper part of the stomach and pulls it tight, like a belt, creating a tiny channel between the two pouches. The band keeps the opening from expanding and is designed to stay in place indefinitely, but it can be adjusted or surgically removed if necessary. Most surgeons perform this operation using a laparoscope.
  • Biliopancreatic diversion: In this procedure, a portion of the stomach is removed. The remaining pouch is connected directly to the small intestine, but completely bypasses the duodenum and jejunum where most nutrient absorption takes place. This weight-loss surgery offers sustained weight loss, but it presents a greater risk of malnutrition and vitamin deficiencies and requires close monitoring.
  • Jaw wiring: This is a form of food intake restriction for temporary use in patients without respiratory problems. It can be effective for short-term weight loss. However, weight regain occurs soon after the wires are removed.
  • Liposuction: This is the most frequent cosmetic operation in the United States in which fat tissue is removed. Relatively small amounts of total body fat can be removed safely, however, and little weight is lost.
  • Vertical banded gastroplasty: This operation divides the stomach into two parts - limiting space for food and forcing the patient to eat less. There is no bypass. Using a surgical stapler, the surgeon divides the stomach into upper and lower sections. The upper pouch is small and empties into the lower pouch - the rest of the stomach. Partly because it doesn't lead to adequate long-term weight loss, surgeons use it less commonly than gastric bypass.

Copyright © 2011 Natural Standard (

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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