Alli is not the only one of it’s kind. There are about six prescription weight-loss drugs on the market that offer great claims. Some, like Alli, block the absorption of fat in the body. Others work in the brain to suppress appetite. But the reality is, no matter how many weight-loss pills you take, they don’t work by themselves.

“The pills we currently have don’t seem to be terribly effective for long-term weight loss,” says registered dietitian Anne Fletcher of Mankato, Minn. “When people go off the pills, many put weight back on.”

Of course, the drug industry (whose sole purpose is to make money) and many dieters remain convinced that a pill is the answer to the nation's growing obesity epidemic. There are some new prescription diet pills are in late stage trials.  One of these is the experimental drug lorcaserin, which is a variation of Fen-phen.  You may remember this famous stutter-sounding drug, which was pulled off the market for causing heart problems. But a few deaths will not deter the drug companies from feeding a hungry market that is looking for an easy solution.  There are at least 30 companies developing weight-loss drugs, with projections that the obesity drug market will grow in the U.S. from $222 million in 2006 to nearly $2 billion by 2016.

The biggest mistake people make in taking diet pills is looking at them as the magic solution to poor eating habits. You can’t turn fat into muscle by taking a pill.  Another thing that fat-blocker will not do is turn crème puffs into health food.

According to Gary Foster, director of the Center for Obesity Research and Education at Temple University in Philadelphia, “"People cannot expect a medication to do it for them. It’s a 50/50 partnership with the pill being half the equation. Exercise, what we eat and our lifestyle habits … are critical to long-term success.”

Anne Fletcher, author of the book “Thin for Life,” found that people who lost significant amounts of weight often had made multiple efforts to lose weight before they realized long-term success. “When we try to change any behavior it takes most of us a few attempts to get it right,” she says.

The truth is, no one really knows how safe any of these drugs are because there have not been any long term studies to really measure the effect, especially for young people who have bodies that are still changing. The Food and Drug Administration has only approved them for adults for up to two years of continuous use.

There are common side effects from most of these drugs as well. Some people have seen increased blood pressure and heart rate with the use of Sibutramine. A fat blocking drug named Orlistat can have embarrassing intestinal side effects. Another drug named Rimonabant (used in Europe, but awaiting approval in this country) may cause nausea, anxiety, depression and insomnia.

The bottom line probably comes from Pat Baird, a dietitian and nutrition consultant for GlaxoSmithKline’s Consumer Healthcare division.  She serves as an online moderator, answering questions for people using Alli.  According to Baird, “The people most successful are those who are ready to make a serious commitment to losing weight and willing to take responsibility for their actions and for change".