Our national obesity epidemic didn't just happen. The people who study the statistics agree with Dr. David Ludwig of Children's Hospital and Harvard Medical School that before the early 1970s, the prevalence of obesity was relatively constant in the United States. As he told the 63rd Scientific Sessions of the American Diabetes Association since then there has been a dramatic increase.

What could have triggered it? Other people have pointed the finger at several different possibilities. But one primary factor stands out:

Your tax dollars at work.

The beginning of the obesity epidemic coincides too close for comfort with what looked at the time like enlightened legislation. The Agriculture and Consumer Protection Act of 1973 established target prices and deficiency payments to replace former price support payments.

Before that time, our government paid our farmers not to grow crops, as unbelievable as it sounds today. When farmers took some of their land out of production, the reduced supply kept prices up.

The 1973 law instead paid farmers to grow crops. When we put it that way, the change sure sounds sensible. One consequence is that Americans now have perhaps the cheapest food in the world at the same time that food prices in the developing world are rising so fast that more people than ever are starving to death.

Americans now spend just 16-17 percent of our income for food, Earl Butz proudly stated in the new documentary film, "King Corn." Butz, who died this year at age 98, was the U.S. Secretary of Agriculture in 1973. He revolutionized American agriculture policy and urged farmers to plant commodity crops like corn "from fence-row to fence-row."

Butz had a lot to be proud of -- as well as a few things to be ashamed of (that the movie tactfully didn't mention), including a horrible anti-black remark that led to his resignation as well as going to prison for income tax evasion.

America's farmers listened to his advice because the more corn they grow the more money they make. The fact that farming has become big business never seemed to bother Butz. He always said "get big or get out," and that's what they did.

The farmers in the Midwest who plant two trillion corn plants each year would lose money on every acre of corn were it not for our benevolent government. The "King Corn" movie shows us the small picture to help us better understand.

"King Corn" is about two friends, Ian Cheney and Curt Ellis, and one acre of corn that they grow near the town of Greene, Iowa. Their acre produced a typical 180 bushels of corn -- about 10,000 pounds -- in a record national harvest. Like other farmers they would have lost money, however, had they not received government payments of $28 per acre, their portion of the $9.4 billion in federal crop subsidies.

Our grain elevators are full. The movie shows what looks like literal mountains of corn stored in the open. What tremendous success Butz achieved in increasing America's crop production!