A majority of American adults have tried dieting to lose weight at some point in their lives, and at any given time, about one-third of the adult population say they're currently dieting, which is why diet books are the one consistent think about the New York Times bestseller list. Yet 60 percent of American adults are overweight or even obese and more than 16 percent of deaths nationwide are linked to that. 

Why do some people succeed at diets while others fail? Dieting is a process that involves a plan to change eating behavior and behaving according to that plan. But the factors that guide diet planning differ from those that guide actual diet behavior, write Marc Kiviniemi,  associate professor of community health and health behavior at the University at Buffalo, and Carolyn Brown-Kramer of the University of Nebraska-Lincoln, in the Journal of Health Psychology.

How people manage their dieting behavior is a big piece of the puzzle. 

"The crux of the disconnect is the divide between thoughts and feelings. Planning is important, but feelings matter, and focusing on feelings and understanding their role can be a great benefit," says Kiviniemi. 

Plans to change behavior are a function of thoughts, the belief that weight loss is possible by making better food choices. But when it comes to making a food choice and decidingto execute the plan, feelings guide behavior.

"If you're sitting back conceiving a plan you may think rationally about the benefits of eating healthier foods, but when you're in the moment, making a decision, engaging in a behavior, it's the feelings associated with that behavior that may lead you to make different decisions from those you planned to make."

The findings highlight the shortcomings of deprivation diets or diets based on food choices that ignore people's preferences.

"First of all, the deprivation experience is miserable. If you didn't associate negative feelings with it to start, you will after a few days," says Kiviniemi. "The other thing that's important is the distinction between things that require effort and things that are automatic. 

Kiviniemi says dieters should seriously consider enjoyment when framing and shaping a behavior change. "In the dietary domain, eating more fruits and vegetables is fabulous advice. But if you have negative feelings about those food choices, they might not represent elements of a good plan. It's not just about eating healthy foods. It's about eating the healthy foods you like the most."