Trial lawyers generally aren’t a picky bunch. They care about two things: making money and laying blame. Their trick is convincing a jury to disregard common sense and blame whomever happens to have the deepest pockets. That’s pretty much what we saw last month at the Public Health Advocacy Institute (PHAI) conference, where trial lawyers and food cops plotted new ways to sue restaurants and food producers over obesity. But as we argue in an op-ed in today’s Washington Times, the lawyers who see big bucks where the rest of us see breakfast have missed the mark by a wide margin.

The problem isn’t breakfast — nor is it lunch, dinner, or anything in between. Obesity’s real smoking gun is America’s growing problem of lethargy. “In a debate in which foods themselves are being held to be largely responsible for increasing levels of obesity,” former FDA Commissioner Dr. Mark McClellan observes, “actual levels of caloric intake among the young haven’t appreciably changed over the last twenty years.” And as we point out in the Times, a growing body of scientific evidence corroborates Dr. McClellan’s point:

Using Census data, the University of North Carolina’s Dr. Lisa Sutherland has shown that teenagers decreased their physical activity by 13 percent since 1980, while their caloric intake rose just one percent over the same period. According to an article published by the American Medical Association, a lack of vigorous physical activity is the main contributor to obesity in children ages 11 to 15.

The same holds true for adults. “A reduction in energy expenditure must be the main determinant of the current epidemic of obesity,” a 1995 study published in the International Journal of Obesity found. And a 2003 study in the American Journal of Preventative Medicine summed it all up by recommending “a focus on increasing energy expenditure, rather than reducing caloric intake.”

Here’s the most amazing thing. Skinnier people tend to eat just as much as heavier people. “Most studies of food intake show that obese subjects do not eat more than nonobese subjects,” reports a study appearing in the American Journal of Clinical Nutrition. Why the weight difference? Heavier folks tend to exercise less.

So why did the lawyers at PHAI pick a fight with food? According to the movement’s self-described leader, John “Sue the Bastards” Banzhaf, it was a matter of convenience: “I can’t sue to make people exercise more,” he said. “But I can do something about food.” To put it more bluntly, billion dollar settlements aren’t going to come from suing high school athletic directors.