You probably know that if you eat more calories than you burn off, you're going to gain weight. It's simple math. But if you keep eating your favourite foods long after you're full, sometimes long after you feel sick from the overeating, your brain may be hindering your weight loss plans.

That drive to overeat -- his own drive to overeat -- is what led Dr. David Kessler to write the book The End of Overeating, (McLelland & Stewart, 2009). "I wanted to understand why that chocolate chip cookie had such power over me," he explains in an e-mail interview. "My own overeating wasn't limited to chocolate chip cookies... cakes, fries, you name it!"

Conditioned hypereating, as he calls it, is identified by three characteristics:
-losing control and being unable to resist eating appetizing foods;
-the inability to feel full and;
-a preoccupation with foods in between meals; or, while eating, thinking about what you'll eat next.
Fat, sugar and salt drives you to overeat
"About 50 per cent of obese people, 30 per cent of overweight people and 20 per cent of healthy weight people score very high on scales of the characteristics of conditioned overeating," explains the former commissioner of the U.S. Food and Drug Administration. "All told, that probably means millions of Canadians struggle with overeating."

Although it's unclear why some people overeat and other don't, what is certain is that the combination of fat, sugar and salt stimulates food intake and drives you to overeat. "Certainly in the States, the business plans of the modern American food companies to put fat, sugar and salt on every corner, make it accessible throughout the day, and make it socially acceptable to eat anytime and anywhere have triggered an increase in overeating," he explains.

How food can hijack your brainSo how can you end overeating? "It's not the stuff of sound bytes or miracle cures, it involves our relationship with food at a fundamental level," he explains. This means long-term strategies, and not an overnight fix.

-Plan meals and practise portion control.  -Choose satisfying foods, those high in hunger-reducing lean protein and satisfying fibre.  -Mentally rehearse what you'll do in the face of food cues -- like skipping the bread basket -- to stay focused and in control.

-Manage the cue-urge-reward-habit cycle and decouple the cue from the reward by seeing that highly palatable food as a negative rather than a positive.  Follow new rules (I'm not going to pick up a box of delicious Timbits at the Tim Hortons next door to my office) to quash the food cue and replace the conditioned behaviour.
-Avoid the cues by identifying the foods and situations that lead to overeating and learn to resist in order to reprogram the brain.

Modify your behaviour
Kessler also suggests finding foods that you like and that you can control and cutting back on portions. "I eat about half of what I used to eat," he explains. "For most of us, we can eat 30 to 50 per cent less and still be 100 per cent satisfied."

In the meantime, it's important to remember that overeating is less about your ability to resistance and more about your behavioural conditioning and food industry manipulation.

"The brain mechanisms that drive us to overeat are integral to what makes us human," Kessler concludes. "Loading fat, sugar and salt into our foods is hijacking the reward circuits of our brains. It's not a matter of willpower. It's a matter of gaining an understanding and giving people the tools to control their overeating."

In fact, these foods are hijacking your brain's reward circuitry, which involves learning, motivation, habit and memory. When you eat a highly appetizing food, it stimulates your brain and gives you momentary pleasure. You'll seek out the same food again -- follow its cues, such as sight, smell, location or even the mere thought of it -- for a repeat of that pleasure and eventually the cycle becomes imprinted on your brain. The memory of the rewarding feeling is no longer necessary to eat that food, it becomes "I'm in this situation, I'm going to eat this."

This conditioning, this learned behaviour, is exactly why diets don't work, explains Kessler. "Once the old neural circuitry is laid down and the old learning is established, sure you can deprive yourself of food for 30, 60, 90 days and lose weight, but after that -- if you go back to the same environment and have not laid down new learning, new neural circuitry -- of course you're going to gain the weight back."