Health messages are simply overwhelmed, in volume and in effectiveness, by junk-food ads that often deploy celebrities or cartoon characters to great effect. We may know that eating fruits and vegetables is good for us, but the preponderance of the signals we get - and especially the signals children get - push us in the direction of junk food.

As a culture, we've become upset by the tobacco companies advertising to children, but we sit idly by while the food companies do the very same thing. And we could make a claim that the toll taken on the public health by a poor diet rivals that taken by tobacco.

Some of the largest companies are now using brain scans to study how we react neurologically to certain foods, especially to sugar. They've discovered that the brain lights up for sugar the same way it does for cocaine...

Each year, food companies use an amount of salt that is every bit as staggering as it sounds: 5 billion pounds.

Take a cup of coffee, keep adding sugar until you reach the point that you like it the most, and then when you add more sugar, you actually like it less. Well, the food industry knows that, and they spend huge amounts of effort finding the perfect spot, not just for sugar, but for fat and salt, as well.

What I found, over four years of research and reporting, was a conscious effort — taking place in labs and marketing meetings and grocery-store aisles — to get people hooked on foods that are convenient and inexpensive.

Every year, the average American eats as much as 33 pounds of cheese. That's up to 60,000 calories and 3,100 grams of saturated fat. So why do we eat so much cheese? Mainly it's because the government is in cahoots with the processed food industry. And instead of responding in earnest to the health crisis, they've spent the past 30 years getting people to eat more. This is the story of how we ended up doing just that.