The Holy Grail for weight-loss devotees is, of course, that magic bullet: a pill that melts away the pounds. There have been several misses, but not one has yet cracked the problem without creating some of its own. Still, though none of these pop-ins will cause last night's malai koftas to vanish into "thin" air, in certain cases of serious and resistant obesity, some of the drugs on the market may — by producing a fillip of quick, initial results — give you the "push" that gets you off the starter's block. To that extent, some of them can kick off a weight-loss programme; they cannot be its mainstay.

Here's the update on their credentials:

Drugs which flush water out of the body. Diuretics (or "water pills", as they're called) increase the rate at which water is excreted from the body. They have the same 'weight-loss' effect as saunas and steam baths: you lose water, not fat, and as soon as you replenish your body with fluids, you'll get all that weight back.

Because diuretics deprive the body of essential minerals like potassium and sodium, they are avoidable unless you have a specific disorder such as fluid retention (and then, only under medical supervision). Diuretics have no legitimate place in a normal weight-loss programme.

Drugs which raise levels of thyroid. The only valid use for these drugs is in those persons who have low thyroid levels. They produce less thyroxin hormone which helps fat-burning, and as a result are likely to be obese. Such persons improve with thyroid therapy. But thyroid drugs are not advisable as a routine prescription for raising metabolic rate in the overwieight. That is because they can achieve this effect in healthy people only when taken in dangerous amounts.

Drugs that depress the appetite. They are also known as anorectics from the medical term, anorexia, which means loss of appetite. They include amphetamines and amphetamine-like drugs. Amphetamines are drugs which stimulate the nervous system; they also increase the metabolic rate and suppress the appetite. Soon, however, the body develops a tolerance for the drug, and it will not have its appetite-suppressant effect at the initial dose. You'll need increasingly stronger doses to achieve the same effect, leading to drug dependency. Besides causing dependency, such drugs can also have direct health hazards such as raising the heart rate (tachycardia) and blood pressure.

Among the different drugs that depress appetite by their action on the central nervous system are:

(i)     Fluoxetine (brand name in the U.S. — Prozac; brand names

in India — Prodep, Fludac.)

(ii)     Fenfluramine and Dexfenfluramine. Both drugs work by

increasing brain levels of a chemical called serotonin: this in turn

suppresses eating by acting on the appetite control centre in the

hypothalamus. Dexfenfluramine has a more specific effect on this

chemical while fenfluramine operates on it indirectly.

Fenfluramine has sometimes been used-in conjunction with an appetite suppressant called phentermine — the so-called fen-phen Combination. Fenfluramine hit the market-place in the late 70s, Dexfenfluramine scrambled in its footsteps. Both drugs however found themselves entangled in one troubling controversy after another until their eventual fall from grace.

Though fenfluramine is chemically related to amphetamines, it does not cause drug dependency. It can however result in psychic disturbances. Neurologists have long looked on it with a jaundiced eye, suspecting that since the drug impacts on the brain's functioning, it could have unwanted effects.

As for dexfenfluramine, the drug has long been known to up the risks of pulmonary hypertension, a rare but fatal disorder characterised by a tightening of blood vessels in the lungs: nearly half of those affected die within four years. Recent research has shown that, used consecutively for three months, dexfenfluramine raises the risk of this illness 30 times.

Following this finding, the American FDA cautioned doctors to reserve the drug for only those whose obesity has brought on serious problems such as high cholesterol, hypertension or diabetes, and who find it physically arduous to exercise. It's also important to remember that nothing is known about the long-term effects of this drug since no studies have yet been done to check them out.

Already, the fen-phen double whammy approach has been forsaken, following the evidence that both, fenfluramine and dexfenfluramine, are associated with serious heart valve defects.

Drugs which temporarily raise the metabolic rate. They are known as thermogenics (eg.ephedrine, and ephedra-based products like ma-huang). After deaths were reported with "Herbal Ecstasy", the American FDA took some brands off the market, but weight-loss formulas can still be bought off shelves in the U.S. and other countries.

Thermogenics supposedly work by increasing the body's core temperature so that you're working in a "hotter" environment and burning more fat. But some experts say they aid weight loss by working as appetite suppressants really, almost like amphetamines. As their effect wears off, you'll crave food, besides feeling fatigued.

Thermogenics are yet to be tested in clinical trials to determine whether they carry the risks of elevated heart rate and blood pressure, as strongly suspected by the medical community. Until these tests are done, they are definitely contraindicated for those with any kind of heart or circulatory problem.

Drugs which produce a feeling of fullness. These drugs are known as bulking agents. Taken with water before a meal, the bulking agent swells in the stomach, producing a sensation of satiety, which takes the edge off your appetite. Though they do not act on the central nervous system and do not have the dangerous side-effects of amphetamines, they do produce tolerance — which means that, over a period, the initial dose is no longer sufficient to bring about the intended effect, and a higher dose must be taken. Besides, the dependency that they cause is unlikely to motivate their user to introduce the diet and other lifestyle changes that constitute the basis for permanent weight loss.

Used too often, or in high doses, they are also likely to have a laxative effect and may even bring on diarrhoea. You can get a similar appetite-suppressing effect eating a high-fibre diet. Bran, for instance, used in soups, or breakfast cereal can blunt the edge of hunger. Wholegrains, wholegrain breads, fruits and vegetables peas and beans are other cheaper ways of bulking up your meal and allowing you to eat fewer calories. They are a safer, healthier alternative to bulking agents.

Drugs that prevent calories from being absorbed by the intestines. These include the "starch blockers" and "fat blockers" which supposedly allow you to eat your cake and lose weight too. But research on starch blockers found that starch was not excreted by pill users — instead they caused malabsorption with noxious side-effects, including nausea, vomiting, cramps, diarrhoea and bacterial fermentation in the gut. For this reason, they proved more appealing in theory than in reality and the FDA in the U.S. banned them.     

The latest drug "off the block" in this category is xenical, which is said to prevent absorption of up to one-third of fat by the body.

Drugs that help your body to burn fuel more efficiently. This category comprises supplements that supposedly enable your body to use glucose more efficiently instead of quickly storing carbohydrates as fat.

The "hottest" weight-loss supplement right now is chromium — as chromium picolinate, which is supposedly more easily absorbed than chromium-alone, and as chromium polynicotinate.

The net effect of its weight-loss claim is that it lowers body fat by preserving muscle.

A much-publicized study injected lab rats with high levels of chromium. Its findings suggested that the mineral could affect DNA binding and consequently promote cancer. While this is not evidence that it can have the same effect when used by humans in much smaller dosages, it does raise concern over long-term effects.

Another American study at the Grand Forks Human Nutrition Research Centre found that when men with sufficient blood levels of iron took 200 micrograms of chromium picolinate, they showed iron deficiencies within two months. The director of the study team, Henry Lukaski, explains, "The chromium picolinate binds with transferrin, the substance that transports iron in the blood. This may cause iron to be knocked out of the body."

Even if chromium supplementation produces no harm, does it produce any positive effects on fat and muscle? Its scoffers believe not, dismissing it as a complete waste of money. One naysayer points out that manufacturers of chromium picolinate stress that weight loss results from doing three things: eating right, exercising faithfully and taking chromium. "They're right about the first two," he sniffs.

There's no scientific evidence whatsoever that chromium supplements help you to lose weight. A study on football players at the University of Massachusetts found that chromium pills did not help them to build muscle or lose fat.

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