New Diet Pills Show Promise for Weight Loss

At 177 pounds, Meg Evans of San Diego, Calif., now has enough agility to play goalie for her amateur soccer team. Evans, a 60-year-old mother of four, had been an athlete all her life, but packed on the pounds as years went on, peaking at 232 pounds.

"I never ate wisely. I love my food. I love to cook. That's me," she said. "The Jenny Craig diet was a good one and I lost the weight, was too late. I was already putting it back on."

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Then, a couple of years ago when her blood pressure shot up, Evans said she had to find a solution. She applied and was admitted as a patient in a blind testing for a new drug called Qnexa -- one of a new class of weight-loss drugs in development.

In the same test group was 42-year-old Chris Dickerson, who had grown up as the pudgy kid, and became dangerously fat as a grown man.

"My grandmother is from Arkansas. She taught my mother how to cook. You know, fried taters, pies, cakes. You name it, she learned how to cook it," Dickerson said.

Overweight his entire life, Dickerson had difficulty even throwing a ball with his sons. "I was tired. I had no energy," he said.

With high blood pressure and fear of developing diabetes, he too, felt compelled to enroll in the Qnexa study.

Doctors and those in the drug industry have high hopes for the new medications. Qnexa is a combination of the appetite suppressant phentermine and an epilepsy drug that makes the patient feel fuller. Another drug in development, Contrave, combines an appetite suppressant and a second drug that speeds weight loss. And Lorcaserin is an entirely new medicine designed to switch off appetite in the brain and maintain metabolism.

"Obesity is a chronic disease and we need to think about chronic medication for it," said Dr. Michelle Look, a family practitioner in the San Diego area, who administered the drug trial.

At first, Evans and Dickerson said they didn't feel much of anything when they began taking Qnexa.

"I really thought I was on the placebo for a long time because I didn't have any side effects," Evans said. "I did finally realize that I didn't have any hunger pains."

"It gives you that full feeling instead of, 'hey, you got to clean your plate every time,'" Dickerson told "Nightline."

Cracking the Weight-Loss Code

Approximately two thirds of the American population is overweight and a third is actually obese. No matter what you weigh, experts say the body has mechanisms to prevent weight loss, which go back to the days in nature when food was scarce and you had to chase it.

While diets can produce short-term loss, most people put it all back on.

"If we took your weight up 100 pounds and you lost just 15 or 20 pounds after that, your body would stop the weight loss. It would lower the metabolism. It would make you think about food," said Dr. Ken Fujioka, an obesity specialist. "That's really hard to beat. So using medications to get beyond that is really where we are headed right now."

Most diet drugs have not worked very well and some have been dangerous failures. Twelve years ago, an anti-obesity drug known as Fen-phen was taken off the market because it was shown to cause heart disease. Two years ago, another drug failed FDA approval because it led to depression and suicidal tendencies.

Phentermine from Fen-phen makes up half of Qnexa. The company claims that it's the non-"toxic" half of Fen-phen that's included in the new drug.

Some doctors are wary of the medicinal approach and stress the merits of hard work, diet and exercise.

"The problem is if we start throwing multiple levers that regulate chemical pathways in the brain, there's a pretty good chance you are going to reap the whirlwind," said Dr. David Katz, director of Yale University's Prevention Research Center. "We have evolved into a quick-fix, active-ingredients, silver-bullet type of society. So, many people would rather wait for a wonder drug to come along to fix their weight control issues, than to do the hard, but more effective work of learning how to eat well, figuring out how to make physical activity a part of their daily lives."

As part of the drug study, both Evans and Dickerson changed either what they ate or how much, and they started to exercise. But an effective diet pill could make it possible for some patients to keep eating while losing weight.

Weight Loss: A $35 Billion Industry

Americans already spend $35 billion a year on losing weight and the drug industry is on the quest to find the next wonder drug to crack the formula for weight loss. Safe and successful weight-loss drugs stand to make billions and billions of dollars in a market starving for a solution.

"There's no doubt that the holy grail of medicine is going to be weight loss, only because all the medical problems -- diabetes, heart problems -- are all related to weight," said Fujioka. "So, if somehow we can get weight down, we correct six to 10 other major problems in the U.S."

Qnexa, the drug administered to patients in the clinical trial, has so far been reported as linked to an average weight loss of 14.7 percent in one year. Contrave's testers report an average loss of between 8.1 and 11.5 percent in their trials and Lorcaserin was linked to 8 percent of body weight.

"Our market research shows that Lorcaserin will be very successful to address the biggest need for this market, which is to allow patients to lose weight in a safe fashion and keep the weight off over a long period of time," said Jack Lief, president and CEO of Arena Pharmaceuticals, who is developing Lorcaserin.

None of the drug developers has reported serious side effects, which have typically been the Achilles heel of many drugs.

But to keep the weight off for a long period of time, some doctors say patients will likely be required to stay on the drugs for years.

"America needs to understand that when you start a weight-loss medication, you can't just start it, expect to get a kick start, and the weight comes down and you can stop it," said Fujioka. "A lot of these medications for people who are seriously overweight are long-term medications -- just like blood pressure, just like cholesterol, you're going to need to take them for years."

Qnexa Shows Positive Results in Study

Qnexa, which both Evans and Dickerson took, was the drug that has reported the most dramatic results.

For Evans, it has been life-changing. Since she lost weight, her blood pressure has gone down, and her knees are no longer as strained. She attributes her weight-loss success to Qnexa.

"[Before] I swear I would get too hungry. Your body gets used to that same amount of food and your body yells at you and I obey my body," she said.

Dickerson went from 343 pounds to 270 in the Qnexa study. Coaching his son's football team, he says he could never have kept up at his earlier weight.

"I don't want to call it a miracle drug because it takes someone wanting to make the change in their life, too, to do the right thing," he said. "You got to want to make the change yourself, too."

Qnexa, Contrave, Lorcaserin all still need FDA approval and are at least a year away from hitting the market.