Weight-loss drugs: What works?

Hope is a funny thing. It gives us strength during the toughest of times, but it can also blind us to certain harsh realities. Consider the tantalizing promise of a miracle in a bottle with its ads featuring washboard abs on size-four women saying: "Thanks to this amazing fat-zapping pill, I lost 30 pounds in three weeks!"

Despite what those bikini-clad women say, the safest amount of weight you can hope to lose in a week is 0.9 kilograms (two pounds). And no matter how well we know that weight loss is best achieved with a reduced-calorie diet and regular exercise, the need to fit into that dress lowers our defences against big promises in small pills. But weight-loss drugs and supplements come with potential known, and unknown, side-effects -- some scarier than others.

Safety first
Because only prescription drugs have supporting research, your doctor is not likely to recommend over-the-counter (or over-the-Internet) weight-loss supplements. In 2005, an initiative by Canada, the United States and Mexico assessing bogus weight-loss products resulted in 734 actions against manufacturers that had cost susceptible dieters billions in wasted dollars. Considering that number likely represents only a fraction of the bad beans in the jelly-bean jar, you should apply more than a scoopful of skepticism before popping the lid.

Here's a primer on the most popular weight-loss drugs and supplements, from supposed hunger zappers to a fat blocker to every gym-hater's dream -- the energy burners.

Hunger zappers
If you can trick your body into thinking it's full, you'll eat less -- or so goes the theory behind a popular prescription weight-loss drug in Canada, sibutramine. The hunger-zapping drug, also known as Meridia, works by increasing levels of norepinephrine and serotonin, two brain chemicals that tell you when you're full. The chief, disconcerting side-effect is risk of elevated blood pressure and heart rate.

The long-term effects of sibutramine (which has been on the Canadian market since 2001) on cardiovascular issues such as heart attack and stroke, as well as overall death rates, are unknown, although a study of more than 10,000 people is under way. Like any prescribed anti-obesity drug, the most people can hope to lose is about five kilograms (11 pounds) over a year or more, says Dr. Raj Padwal, assistant professor in the division of internal medicine at the University of Alberta in Edmonton.

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Phentermine (also called Adipex-P or Ionamin), another brain-chemical-altering drug that works only on norepinephrine, is available but rarely prescribed in Canada. When prescribed with fenfluramine (Fen-Phen, as the combined drug was known) it caused serious heart damage; it was pulled off shelves in the late 1990s.

Balancing risks and benefits
Padwal is more skeptical about effectiveness and safety than many other physicians when it comes to sizing up the risks versus benefits of prescription drugs. His research, published in the International Journal of Obesity last year, showed very poor long-term usage rates of the two leading drugs -- sibutramine and orlistat. On average, the drop-out rate in studies on the leading prescription drugs is between 30 and 50 per cent -- not a very encouraging sign, adds Padwal.

But Dr. Arya Sharma, a professor of medicine at the University of Alberta, says that prescription drugs are safer than natural products because they are "generally better studied before being marketed." Balking when asked about cost, Sharma asks, "What's the cost of long-term obesity?"

Padwal says he's not against anti-obesity medication. He says he'd even like to see more well-researched treatments at the disposal of physicians such as himself who are trying to treat obesity.

Cravings? What cravings?
Rimonabant (called Acomplia in the U.K., where it is sold) is another brain-altering medication that blocks cravings. It was under review in the U.S., but the American Food and Drug Administration recently denied approval for the drug. There is concern about at least one foreboding side-effect: depression.

"Usually by the time I explain to patients that the drugs are expensive, that there are adverse reactions and that the weight loss is only three to five kilos, they say ‘no thanks,'" says Padwal. Instead, they may consider surgery such as stomach stapling, when advised.

Natural doesn't always equal safe
The problem then is that patients who don't like the sound of the prescription drugs' side-effects or surgery are likely to turn to over-the-counter supplements, not realizing that "natural" doesn't mean side-effect free. That irks a lot of physicians.

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Dr. David Lau is a professor of medicine at the University of Calgary and the president of Obesity Canada, a not-for-profit organization. He says that Obesity Canada assessed more than 130 alternative drug therapies for weight loss as part of the development of the new Canadian clinical guidelines for obesity. None were deemed effective in the battle of the bulge.

Supplements that curb your appetite
Popular supplements claiming to help suppress appetite include guar gum, glucomannan and hoodia. The first two are innocuous soluble fibres that create feelings of satiety as they absorb water and pass through the intestinal tract.

A combined analysis of 11 trials on the weight-loss benefits of guar gum showed no benefit. Glucomannan, from the roots of the konjac plant, shows slightly more promise: A 2005 review of studies on the supplement in Alternative Therapies in Health and Medicine indicated two to four grams per day were well tolerated and resulted in significant weight loss. But several other reviews say the proof is limited at best.

Hoodia, an endangered African plant species with an active ingredient that is thought to somehow stave off hunger, was buoyed by a massive e-mail spamming campaign in North America in the first half of 2006. But there are no studies showing that it works (despite what the Hoodia Power-Pops lollipop packaging tells you) or assessing long-term side-effects.

Is hoodia a hoax?
Early reports from a researcher at Pfizer, which interestingly dropped its rights to hoodia in 2002, stated that it could have unwanted effects on the liver and that dieters should be wary. A 2006 Consumer Reports investigation proclaimed there is no evidence that it works.

Hoodia supplements are being sold in Canada, but the Natural Health Products Directorate (NHPD) has yet to authorize any specific products, and rated the supplement a low-risk priority. Until the NHPD gets through the backlog of products waiting to be approved, you may notice some products labelled "NHN# pending."

This labelling is in violation of Health Canada's policy and does not assure consumers of anything. Also, be on the lookout for over-the-counter supplements that contain sibutramine. Several products containing this ingredient recently made Health Canada's adverse reaction list. They are manufactured in China and being sold illegally in Canada.

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The fat blocker
Orlistat, a.k.a. Xenical, came onto the Canadian market in 1999 and is still the No. 1 prescribed weight-loss drug. It works by preventing the body from absorbing fat in the intestine, and as long as you follow a low-fat diet, it can eliminate about 150 calories from fat from the food you eat each day. Small potatoes, really, considering you need to cut back 500 calories a day, or roughly 3,500 calories a week, to lose two pounds.

Also, Orlistat comes with more severe potential side-effects, including oily stool, anal leakage, gas and bloating, and is widely criticized, including by Rosie Schwartz, a registered dietician from Toronto, and by Padwal. They believe the drug causes malabsorption of important fat-soluble vitamins.

Orlistat is also the most expensive prescription drug, at $80 to $100 per month plus a dispensing fee. Your doctor is the best person to decide whether this drug is good for you. A lower-dose version of Orlistat has received conditional approval for over-the-counter sale in the U.S., so it's just a matter of time before it's available here.

Energy burners
Watch out for supplements claiming to boost your metabolism or help you burn more calories, such as bitter orange. Stimulants, which work on the central nervous system to speed up your metabolism, can be addictive, and often come with dangerous side-effects. Plus, cautions Lau, it is important to remember that any weight you lose on a supplement is mainly water, not fat.

You may recall some buzz about ephedra, an alkaloid plant compound that, combined with caffeine in weight-loss products, was banned in Canada in 2002 after 60 adverse events, including strokes and seizures, were reported (although it is still available in decongestants). The drug caused almost 20 deaths in the U.S. in the late 1990s.

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Nevertheless, ephedra preparations are still being sold in combination with caffeine in health food stores and gyms, much to the chagrin of Health Canada. (Beware of products containing Ma Huang, which is Chinese ephedra, and also illegal.) Like ephedra, bitter orange (a citrus tree extract) contains a stimulant that has been linked to stroke and heart problems. It is not approved by Health Canada for use in weight loss, although it is used in traditional Chinese medicine for other remedies.

Another one to miss is guarana, the seed of a Brazilian fruit, which works like caffeine as a stimulant on the central nervous system. You may find it in energy drinks and even daily multivitamins (One-a-Day WeightSmart Advanced vitamins in the U.S. contain it). While it appears to be safe, there is no solid research supporting its effectiveness.

The fat and carb busters
Lastly we get to a host of supplements that claim to interfere with fat synthesis or speed fat breakdown, such as green tea extract, hydroxycitric acid, conjugated linoleic acid (CLA), L-carnitine and one very popular carb-buster: chromium. In a nutshell, experts say there is no evidence that they're effective at fighting fat. In fact, high doses of green tea extract can be dangerous, with side-effects such as heart palpitations and liver damage, while chronic use of chromium may cause muscle and kidney damage.

Use of CLA may cause gastrointestinal distress, raise blood cholesterol levels and impair insulin resistance. The fundamental problem with these supplements is that their manufacturers claim you can somehow alter your body's natural processes, which is entirely unproven.

Clearly, you take your chances when opting to use any short-term weight-loss aids. Given the limited supporting evidence, your money will be better spent on a gym membership. Hope is essential for a positive outlook, but it doesn't belong on the dieter's list of weight-loss remedies.

If weight-loss drugs aren't your thing, you may be more comfortable following a dietitian's weight loss secrets for healthy, safe dieting.

This article was first printed in the February-March 2008 issue of Homemakers Magazine. Click to subscribe online and never miss an issue.