A new ally in the battle against the bulge arrives in in pharmacies and retailers in the United States on Friday, when alli, the first over-the-counter diet pill, approved by the Food and Drug Administration (FDA), goes on sale.Unlike the hundreds of other weight-loss products for sale without a prescription, alli (pronounced AL-eye), is the only diet drug deemed safe and effective by the FDA. Dieters who stick to a low-fat, reduced-calorie diet and exercise regularly can lose more weight when they add the fat-blocking pill, according to manufacturer GlaxoSmithKline.Some doctors are concerned about potential abuse, especially among youth, who are not authorised to take alli, and many people are skeptical that any pill can help people lose weight. Still others say potential side effects—suchas gas and loose stools—may be a deterrent to those contemplating the drug.Even so, Karla Scanlan, a resident of Michigan, says she may try alli if she does not lose 20 pounds in the next few months by eating a healthy diet and working out. “I might need a little help to get me over the hump,” said Scanlan, who has tried low-carb diets and prescription weight-loss drugs in her quest to lose weight.“But I wouldn’t take it as a substitute for eating healthy and working out.”Only two FDA-approved weight-loss drugs, Orlistat and Meridia, are currently on the market. But these can be bought only with a prescription.In February, the FDA approved the sale of alli, a reduced-strength version of Orlistat, for people over age 18. Users should not take more than three pills in one day. Taken with meals, alli works by blocking digestion of one-quarter of the fat consumed. Billed as a complete program me rather than just a pill, the drug will come with a starter kit to help users understand how to find fat in their diets at home and when eating out. Alli also comes with an online support plan ( myalli.com), which gives people tailored messages on a weekly basis.“We don’t want people to try alli. We want people to commit to a low-fat, reduced-calorie lifestyle,” said Brian Jones, vice-president of communications for GlaxoSmithKline. The drug maker emphasises that people can only take alli when eating 15 grams of fat at each meal. A higher fat consumption could lead to unsavoury side effects including gastrointestinal issues such as urgently needing to go to the bathroom. The pharmaceutical company has been up-front about this, even recommending that people wear dark pants or bring a change of clothes to work until they adjust to the drug.