PHOENIX -- If you're one of those people who diets and exercises, but just can't seem to shed those extra pounds, a small tweak in what you're doing could make a world of difference.
In her new book, "Why You Can't Lose Weight," metabolic and anti-aging expert Dr. Pamela Smith offers 18 common reasons you might not be losing weight and explains what you can do to overcome those obstacles.
The book is divided into four parts that tackle lifestyle, health disorders and biochemical problems, with the last section helping you put together an easy-to-follow weight-loss program.
"You'll discover how to lose weight and enjoy radiant heath," promises the book's description on Amazon.com.
When Smith, the director of the Center for Healthy Living and Longevity in Traverse City, Mich., sat down with 3TV's Kaley O'Kelley Thursday morning, she explained why stress can be such a big barrier when it comes to losing weight.
"A hormone, cortisol, is the stress hormone," she said. "You have to have cortisol to live so the body will produce it, but if cortisol levels stay high, one of the side effects of that is weight gain, particularly around the middle. … The goal is to mitigate stress."
Food allergies can be an issue, as well.
Smith said people might not recognize allergies for what they are because food allergies come in two forms -- IgE and IgG.
IgE, which can result in inflammation, is the type of allergy with which most people are familiar. Triggers include foods like peanuts or shellfish, as well as things that are not ingested like latex, and plants, including poison ivy, poison oak or poison sumac. Regardless of the trigger, the swelling and respiratory troubles come on almost immediately.
With IgG allergies, which are more common than people realize, the response comes later, sometimes hours, even days, after ingestion. It's that lag that makes IgG allergies difficult to diagnose.
"Two days later you might get a headache. You might get a gut disturbance," Smith explained.
Weight gain also is a response to IgG allergens.
A blood test is required to look at IgG responses. A metabolic medicine specialist can explain what the results mean, giving you a list of foods to which you are allergic.
"The interesting thing is people tend to craves foods they're allergic to," Smith said. "Epinephrine and norepinephrine, which give you a high, go up in the body when you eat these kinds of food."
Smith said she's probably allergic to chocolate although she refuses to have herself tested for it.
Knowing exactly what you're allergic to, according to Smith, actually can help you lose weight.
"Avoiding [those foods], most patients will lose five, or even 10, pounds," she said.
Smith's book goes beyond the conventional wisdom of simply burning more calories than you take in.
"If it were that simple, everyone would be the weight they want to be," she said.
"Why You Can't Lose Weight" is available online and from the Center for Healthy Living and Longevity.