Fort Lauderdale, Fla. ? For two years, George Hegedus has avoided expensive diet plans and made it to the gym barely three times a week. At 270 pounds, the Coconut Creek resident said he needs something to help combat the fat calories.

So when alli, the first federally approved over-the-counter diet pill, hit South Florida drugstore shelves Thursday, he drove to a Walgreens store on his lunch hour and bought a starter pack: 90 pills at $59.99.

“I hope it helps take calories off, but it’s not a magic pill,” said Hegedus, 42, a structural engineer.

Drugstores reported growing consumer interest in the new diet pill, which is being rolled out nationwide this week with an unprecedented $150 million marketing campaign. Although the drug has been available at greater strength by prescription since 1999, this is the first time it is available over the counter to overweight adults.

The pill works by blocking about 25 percent of the body’s absorption of fat in the digestive system by attaching to natural enzymes that would otherwise break down fat.

Alli’s London-based manufacturer, GlaxoSmithKline, recommends taking it along with a low-fat diet and exercise. Consumers who don’t stick to a low-fat diet can experience some unpleasant side effects, such as oily discharge, diarrhea and gas.

The Food and Drug Administration approved the pill in February, at half the strength of its prescription version, sold under the name Xenical. GlaxoSmithKline is promoting the pill with books, a TV commercial and educational CDs.

Drugstore representatives said many consumers were putting in pre-orders for the drug before it hit the shelves Thursday.

“We’ve been getting a lot of calls and we’ve taken a number of pre-orders through the Web site,” said Carol Hively, a spokeswoman for Walgreens. “We expect this to be a big product.”

But dietitians and pharmacists say that, despite the buzz, it does not change the classic formula for weight loss: eating less and moving more.

Heather Fisher, a Florida State University dietitian and a member of the Florida Dietetic Association, said she is concerned about the nearly 200 students with weight and body-image issues she sees monthly.

She worries that without supervision, some young women might abuse the drug in overzealous attempts to lose weight.

“Over-the-counter lends itself to misuse,” Fisher said.

Some people should not take alli at all, including those with problems absorbing food, gallbladder disorders, certain kidney problems, organ transplants or who are pregnant or breast-feeding a child. Customers taking medicine for diabetes or thyroid should consult a doctor first. Consumers also are advised to talk with their doctors before starting alli to make sure it will not interfere with other drugs they take, such as cyclosporine.

While the drug was tested in children as young as 12, the FDA has restricted alli sales only to people over 18, who will have to show ID to buy it.

GlaxoSmithKline said its testing showed the drug to be safe, and the FDA agreed. But the consumer group Public Citizen has criticized the FDA for approving alli for over-the-counter sales, saying the prescription strength was linked, in a few patients, to the formation of lesions in the colon, which can develop into cancer.