Serial dieters know very well that going on a diet doesn't guarantee success. Things can go wrong. Before you even know what has happened, your early diet success may give way to backsliding and weight gain.

The problem is, a new study suggests, it takes more than a plan to change a behavior because our feelings get in the way, and those emotions guide our behavior more than our plans do.

It's good to know which foods are healthy, but how you will feel about eating those foods is probably more important for your weight loss plan to be successful.

Most people have tried going on a diet to lose weight. In fact, about one-third of the American population is on a diet at any given time. So if over 100 million people are dieting, why are 60 percent of us overweight or obese, and why are 16 percent of deaths in this country related to diet and exercise?

It's good to know which foods are healthy, of course, but knowing how you will feel about eating those foods is probably more important for your weight loss plan to be successful.

“There is clearly a disconnect if we have a majority of the population that has tried to lose weight and a majority of the population that is overweight. People are planning to diet and trying to diet, but that’s not translating into a successful weight loss effort,” said Marc Kiviniemi, a public health researcher at the University of Buffalo, in a statement.

Certainly there are many factors, ranging from environmental to biological, that determine how effectively people manage their weight, but a large part of the success — or failure — of a diet is determined by how people behave.

Dieting As Behavior Change

When a person decides to go on a diet, they are planning to change their eating behaviors. However, the factors that guide creating a diet plan aren’t the same factors that guide dieting behaviors. There is a divide between thoughts and feelings, and while planning is important for a diet to be successful, a person’s feelings matter and need to be understood, according to Kiviniemi.

Plans reflect beliefs that better food choices will result in weight loss. But actually making a better food choice is the result of how a person feels at the moment a choice has to be made. Feelings, not the plan, control the behavior that follows.

The factors that guide creating a diet plan aren’t the same factors that guide dieting behaviors.

“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,” says Kiviniemi.

Why Deprivation Doesn't Work

That's the problem with diets. Most diets are based on deprivation, whether it is deprivation of entire food groups or deprivation of specific foods, and most diets don’t take people’s food preferences into consideration. While dieters may be able to tolerate the unpleasant feeling of deprivation for a time, it requires a lot of self-control that can only last so long for most people.

It is far better to see yourself as giving yourself something you like, rather than taking way every food that gives you pleasure.

The best weight-loss plans include the foods you enjoy . Seeing yourself as giving yourself something you like, rather than taking way every food that gives you pleasure, will keep your diet on track. Why plan a diet around eating more green leafy vegetables if you really don’t like green leafy vegetables? Instead plan a diet that emphasizes the healthy foods you do like (and maybe add tasty recipes with dark leafy greens).

When you are getting ready to diet, Kiviniemi says, think ahead about how you will handle your food feelings when they appear. Maybe you will grab a book or magazine or reach for a handful of carrots or take a walk.

It's good to know which foods are healthy, of course, but knowing how you will feel about eating those foods is probably more important for your weight-loss plan to be successful. Your weight-loss plan needs to include snacks and treats — maybe smoothies and popcorn — that will make you feel you are treating yourself rather than simply depriving yourself.

The study is published in the Journal of Health Psychology.