Dec.18 -- The author of a new diet book defended his new drug combination therapy against criticism that he has yet to prove that it is safe, or that it works in a published scientific study.
Dr. Paul Rivas, an obesity specialist and author of the new book Turn Off the Hunger Switch, believes the combination of phentermine and antidepressants such as Zoloft and Prozac effects brain chemistry to promote weight loss.
"I've tried it now on over 8,000 people, probably close to 10,000 over the last eight years," said Dr. Rivas in an interview today on Good Morning America.
Rivas claims that it would be very difficult to do a study on this combination of drugs. "The reason that is is because we customize every patient, so we don't have a standardized approach that you could study," said Rivas.
Dr. Timothy Johnson, ABCNews' medical editor, disagreed with Rivas' claims during the GMA segment. "The unwritten rule was if you do not publish you should not promote, and I still believe that's the way to go," said Johnson. "I'm always concerned when you combine things, and I disagree respectfully that you can't study certain [combinations]. If you're going to start using something on a wide scale, and promote it to the public, I think you can study it in various ways and should."
Drugs as ‘Future of Treatment’ for Obesity
On its own, Phentermine has been shown to suppress the appetite, and the antidepressants function to overcome deficiencies of brain chemicals that affect mood.
Rivas believes such chemical imbalances are the cause of obesity in many people, and that antidepressants can help return chemicals levels to normal.
Dr. Richard Atkinson, professor of medicine at the University of Wisconsin in Madison and the president of the American Obesity Association, says he also prescribes the phen-antidepressant drug combination to his obese patients, but notes the combination has yet to be proven more effective for weight loss than phentermine alone.
"Obesity is a chronic disease," says Atkinson. "Pretty much every other chronic disease I can think of requires more than one drug, and I think that drugs are going to be the future of the treatment of obesity."
Rivas believes the key to the drugs' success is using low doses of a combination of these drugs in order to balance the chemicals in the brain, while avoiding any unwanted side effects.
"90 percent of people get a very significant weight loss, at least 10 percent or more," said Rivas.
Critics Say Pills Don’t Remove Pounds
Not everyone is convinced that pills alone can make people lose weight.
"People want the easy answer when it comes to weight loss, and unfortunately it just doesn't exist," said Connie Diekman, director of university nutrition at Washington University in St. Louis. "They still have to do the hard work of learning how to make better choices and get the regular activity."
Other experts point out that publishing results of drug effects in a regular book is not the same as a publishing scientific study data in a medical journal that has been analyzed and reviewed by the scientific community.
"If you don't have the research you shouldn't be making the claims," warns Keith Ayoob, a spokesperson for the American Dietetic Association, and associate professor of pediatrics at Albert Einstein College of Medicine.
A major concern is that the FDA has not yet approved the use of these antidepressants for the treatment of obesity.
However, Rivas points out that both phentermine and these types of antidepressants have been proven to be very safe when used alone, so he says he and other doctors are making the assumption that the combination is also safe.
Many diet experts warn that taking any medication can have side effects, and that no pill can make you lose weight without changes in lifestyle.
"What I would suggest they think about number one is their health ... and then number two are you ready to make changes in your eating while you use the medication," said Diekman.
Rivas, on the other hand, believes that altering the balance of brain chemicals also changes people's attitudes about food and exercise.
"When you change their [brain chemistry] it happens by itself," said Rivas. "They start to want healthy foods. The other thing that happens to them is they start to develop a desire to exercise."
In the Genes
Some experts believe obesity is controlled in large part by genetics. Using the analogy of a loaded gun; a person's genetic history cocks the gun, and environmental influences pull the trigger.
Scientists believe the genetics component evolved to help humans survive famines by allowing them to store fat better. People who are better adapted to store fat are now faced with a society where food is abundant, so it is inevitable that they will gain weight.
"A very positive genetic attribute has now become a negative one," said Rivas
But other experts believe the environment is more of an influence than genetics.
"I think certainly the influence of environment is probably stronger than genetics at this point," said Ayoob. "The gene pool hasn't changed; what has changed is the environment."