In more extreme cases of obesity, doctors may turn to prescription drugs and even surgery, especially if their patient’s obesity is associated with other life-threatening health conditions. What’s an extreme case?

The National Institutes of Health recommend the use of prescription medications for weight loss only for people who have tried nondrug strategies without success. If you have a BMI of at least 30 or a BMI of at least 27 along with other obesity-related medical conditions, your doctor may recommend medications, typically as an addition to diet, exercise, and behavioral therapy.

The drugs the Food and Drug Administration has approved for weight loss fall into two categories:

• Those that suppress your appetite
• Those that reduce your digestive system’s ability to absorb nutrients.

There are many drugs in the first category, but some are approved only for short-term use, and most have relatively limited weight-loss effect, and so are not strongly recommended for patients with heart disease, high blood pressure, or advanced cardiovascular disease.

A review of one of these drugs, sibutramine (trade name: Meridia) revealed that it is effective in promoting weight loss but had mixed effects on cardiovascular risk factors. There was no direct evidence that treatment with sibutramine improved health outcomes.

The only FDA-approved drug in the second category is orlistat (trade name: Xenical). It cannot be used by patients who have digestive problems such as pancreatitis or a gallbladder condition called cholestasis, nor can it be taken by patients who are also taking cyclosporine, a medication often given after organ transplants.

Otherwise, however, it is safe for people with heart disease to take this drug. Diarrhea is an occasional side effect. Recently, researchers have found that certain drugs prescribed for epilepsy and migraine headaches also significantly reduce the weight of those taking them. They may alter the brain circuits that signal hunger and fullness.

But these drugs have received little clinical research and, although some doctors are prescribing them for weight loss, they are not approved by the FDA for that purpose. Another drug that is under testing, rimonabant, has had a promising start.

In a study presented at the annual meeting of the American College of Cardiology, investigators randomized 1,036 overweight or obese patients to placebo, 5 mg rimonabant, or 20 mg rimonabant for one year.

Patients in the 20 mg group lost 15 pounds more than patients on placebo, and also experienced improvements in waist circumference, HDL, triglycerides, and many other markers of risk. This drug is also not yet approved by the FDA. Several other drugs are also under study. Surgical procedures to reduce excess weight are used rarely.

The clinical guidelines reserve the use of surgery for severely obese patients that is, for those with a BMI of at least 40, or a BMI of at least 35 combined with obesity-related medical complications and even then, only after they fail to respond sufficiently to medication.

Obesity surgery (you may hear it called by its medical name, “bariatric surgery”) reduces the size of the stomach. This surgery, which is receiving a lot of attention, makes a person feel full sooner and also reduces the desire for high-carbohydrate foods. Patients who undergo this kind of surgery may eventually lose 50 to 60 percent of their excess weight, and may also see a reversal of other obesity-related medical problems.

But this surgical procedure is a radical last option; it necessitates a permanent change in lifestyle and diet and is still unsuccessful in one out of every five cases. In addition, it may require more than one surgery and may result in anemia. Nevertheless, for some people it may be the best option.

Frequently Asked Questions

What about dietary supplements and herbal preparations?

There have been many over-the-counter supplements and remedies that claim to help with weight loss, including: chitosan, chromium picolinate, conjugate linoleic acid, ephedra alkaloids (“ma huang”), and garcinia cambogia. There is little research to demonstrate that any of these supplements are effective.

Some of the most popular of these alternative medications contained ephedra, which is now banned by the FDA. The expert guidelines do not recommend any of the over-the-counter medications.

If the combination of dietary changes, exercise, and behavior therapy has failed to bring your weight into normal and safe ranges, you should talk with your doctor about the option of taking medications that are well researched and specifically approved for the treatment of overweight and obesity.

How quickly can I expect to lose weight?

According to weight-management experts at the National Institutes of Health, your initial goal should be to lose 10 percent of your starting weight. A reasonable time for losing this first 10 percent is anywhere from three to twelve months.

For instance, if your BMI is between 27 and 35, cutting down your calorie intake by 300 to 500 calories per day should result in a weight loss of about 0.5 to 1 pound per week. If your BMI is over 35, cutting down your calorie intake by 500 to 1,000 calories per day will lead to a weight loss of about 1 to 2 pounds per week.

Both of these approaches work out to a 10 percent weight loss over approximately six months. Losing weight more quickly than this makes you more likely to regain the weight, since such rapid loss usually occurs through drastic—and unsustainable— changes to your diet or lifestyle. Worse, rapid weight loss can cause other health problems, such as gallbladder stones.

Do the guidelines for losing weight apply to older adults?

Because the research is limited in this group, the guidelines are currently not very specific about recommending weight loss in older people. There is some evidence to suggest that age alone should not prevent treatment of obesity.

Other evidence suggests that being mildly overweight is not a risk factor for heart disease in the elderly and therefore weight reduction is not needed in such cases. One concern is that older people may be more sensitive than younger adults to overall reduced nutritional intake.

There is also a higher risk in older adults that participation in a weight-loss program may mask weight loss that is actually caused by an underlying illness. Therefore, the experts recommend a careful assessment of the benefits and risks of weight loss for anybody age sixty-five or older. Weight loss in this group needs to be monitored carefully.

What about commercial weight loss programs and diets?

There are hundreds of heavily promoted commercial diets and weight-loss programs. The best programs are based on strong nutritional principles and do not promise to be either quick or easy. Many, of course, promise exactly that and, since such results can be achieved only through drastic action (if at all), are not based on sound nutritional principles.

That means two things. First, they may be harmful to you. Second, there’s little chance you’ll be able to keep off the weight you lose. If you are considering a commercial weight-loss program, talk it over with a doctor and/or nutritionist first. You will want to choose a program based on sound principles and one that makes realistic claims about what it can help you achieve.

What about low-carbohydrate diets?

Diet fads come and go. The latest is the “low-carb” diet, which emphasizes cutting—in some cases even eliminating—the breads, pastas, rice, and other carbohydrates you consume. It’s actually true that most Americans consume cabohydrates in excess.

A low-carbohydrate diet may ultimately be proven safe and effective, but currently its benefits are being debated. A recent review of all the published studies of low-carbohydrate diets found that the evidence supporting the claims of these diets is weak, primarily because very few rigorous studies have been conducted on low-carbdiets, and most of those studies were of short duration.

The primary finding was that weight loss in these studies appeared to be more related to calories than to carbohydrate content. The good news is that the studies did not indicate that the diet was harmful, though the long-term effects could not be assessed.

So, despite the enthusiasm of advocates for this diet and recent small trials suggesting that low-carb diets have a lot of promise, the medical jury is still out. Currently, the nutrition experts who create the American Heart Association’s dietary standards don’t endorse it.

And as a practical matter, the truth is that carbohydrates are a valuable and easily affordable source of energy. Eliminating them entirely from your diet means you’ll have to get the calories you need from other sources—sources that may not be good for your overall health, such as fats.

And for people over age sixty-five, whose nutrition may already be compromised, a low-carb diet may be quite harmful. If you choose to pursue a low-carbohydrate diet, you should ensure that you get adequate vitamins and minerals in the foods that you do eat.

You should also check your cholesterol since the increase in fat intake may affect your levels. It is best not to feel free to indulge in eating as much fat as you would like. The bottom line is that you need to find what works best for you.