At least three new prescription diet drugs are in the final stages of development as pharmaceutical companies race to see which one will have the next big diet medication to hit the market.

Some hopeful news from the research: obese patients who took one of the medications along with cutting calories and exercising lost about 15% of their starting weight in a year.

The companies still have to submit their new drug applications to the Food and Drug Administration and go through a rigorous review and approval process. Even if the medications get the government's OK, it will be a year or more before they are available to the public.

Many obesity researchers say safe and effective weight-loss medications can save lives -- and money -- by curbing the incidence of weight-related diseases such as diabetes, heart disease, stroke and some types of cancer.

"Losing weight is hard, and we need more tools in our toolbox to help patients," says Donna Ryan, associate executive director for clinical research at Pennington Biomedical Research Center in Baton Rouge. She's president-elect of the Obesity Society, a group of weight-loss researchers and professionals who will discuss new diet medications at their annual meeting next week.

Other obesity experts agree. "We are going to need many different medications in order to treat obesity effectively in the same way we have many different drugs to treat high blood pressure," says Louis Aronne, director of the Comprehensive Weight Control Center at New York-Presbyterian Hospital in New York. He has conducted research on all three new drugs.

The new drugs are intended for people who are obese, about 30 or more pounds over a healthy weight, or who are overweight and have risk factors such as high blood pressure.

During the research on the medications, patients were encouraged to eat healthier, cut calories and increase physical activity. Three of the diet drugs in the final stages of research include:

Qnexa from Vivus. It incorporates low doses of two previously approved prescription medications: the diet drug phentermine, and topiramate, which is used to treat epilepsy and chronic migraines. Phentermine reduces appetite; topiramate increases the sense of fullness.

In two separate studies, the mean weight loss was 13.2% (30 pounds) and 14.7% (37 pounds) for patients who were treated with full-dose Qnexa for 56 weeks. When people who didn't complete the trials are included, the percentage of total weight lost drops to 10.4% to 11%. Most common side effects: dry mouth and tingling in the toes and fingers.

Lorcaserin hydrochloride from Arena Pharmaceuticals. It works on brain chemistry to induce a sense of fullness. Patients who stayed on lorcaserin combined with lifestyle changes for one year lost an average of 17 pounds. About two-thirds of lorcaserin patients lost at least 5% of their body weight; about a third of those who took the placebo and made lifestyle changes accomplished this. The most responsive 25% of patients lost an average of 35 pounds. The most frequent side effect: headaches.

Contrave from Orexigen. It combines two drugs now on the market: bupropion, an antidepressant and smoking cessation medication, and naltrexone, currently used for alcohol and opioid addiction. It works to fight food cravings and improves the ability to control eating. The research shows patients lost about 6% to 9.3% of their starting weight in a year on the medication. The most common side effects: nausea, constipation and headache.

Some patients in the drugs' trials had improvements in blood pressure, cholesterol, triglycerides and blood sugar control.

Treating obesity may be the most cost-effective way of addressing many chronic illnesses that are driven by excess body weight. When you go to the doctor now, they treat your high blood pressure, diabetes and your cholesterol. Weight could be the primary target of treatment because by treating your weight, not only will you get the diabetes, high blood pressure and high cholesterol, but you'll get the many other underlying problems caused by your excess weight. We could reduce health care costs by managing the root cause.