According to the food antagonists and trial lawyers driving today’s hysteria over the so-called “obesity epidemic,” restaurants, school vending machines, soda, and a myriad of convenient, inexpensive, tasty food options are to blame for expanding waistlines. Can’t fit into last summer’s bathing suit? They say you’re the victim of burger bombardment. Beginning to pinch more than a inch around your midsection? You may have fallen into dairy’s “dangerous trap.” In their blind zeal to blame food for any and all weight-related woes, our nation’s nutrition zealots conspicuously gloss over obesity’s largest contributor: a marked reduction in physical activity.

According to Former FDA Commissioner Dr. Mark McClellan, those who blame our love handles on food are barking up the wrong tree:

So it’s perhaps surprising that, in a debate that has often focused on foods alone, actual levels of caloric intake among the young haven’t appreciably changed over the last twenty years.

The President’s Council on Physical Fitness and Sports has noted that “Inactivity might be a far more significant factor in the development of obesity than overeating.” Of course, you won’t hear this from the food police, but numerous scientific studies support these assertions.

A November 2000 study published in the American Journal of Clinical Nutrition found: “The lack of evidence of a general increase in energy intake [food] among youths despite an increase in the prevalence of overweight suggests that physical inactivity is a major public health challenge in this age group.” Research conducted by the University of North Carolina’s Dr. Lisa Sutherland also points to physical inactivity as the principal cause of childhood obesity. “From 1980 through 2000,” Dr. Sutherland writes, “obesity increased 10 percent, physical activity decreased 13 percent and caloric intake rose 1 percent among U.S. adolescents.”

Kids just aren’t getting enough exercise at home or at school. A study published in the June 2000 issue of the journal Pediatrics discovered that “only 21.3 percent of American adolescents participate in at least one day of physical education each week.” The Centers for Disease Control and Prevention (CDC) reports that “Only about one-half of U.S. young people (ages 12-21 years) regularly participate in vigorous physical activity. One-fourth report no vigorous physical activity.”

Sedentary behavior is is also a major cause of obesity in adults. According to the CDC, only “15 percent of U.S. adults engage regularly (3 times a week for at least 20 minutes) in vigorous physical activity during leisure time.” It also notes that “60 percent — well over half — of Americans are not regularly active … [w]orse yet, 25 percent of Americans are not active at all.” In 1999 the International Journal of Obesity published a study that bluntly stated: “A reduction in energy expenditure must be the main determinant of the current epidemic of obesity.” This study also found that people who exercise the most had a 57% lower chance of being obese.

The National Bureau of Economic Research observes that abundant, cheap food is not the major cause of our expanding waistlines. According to a 2002 study conducted by economists for the Bureau, fully 60 percent of our national weight gain is “due to demand factors such as declining physical activity from technological changes in home and market production.” And according to research reported by the USDA, “After 14 years of working, those in the least sedentary occupations have about 3.5 units of BMI less than those in the most sedentary ones.” That’s about 20 pounds for the average woman.

Food cops continue to sound the battle cry for marketing restrictions, “sin” taxes, and frivolous obesity lawsuits — claiming that red tape around the dinner plate is the solution to a slimmer America. Yet reality and science suggest that what America actually needs is to focus on the latter half of the “calories in = calories out” equation.