Here is the so-called mystery: Americans are exercising more, but the national obesity rate keeps rising. How can that be?
The answer is pretty obvious. As my personal trainer (the only person standing between me and a gut hanging over my belt) has told me many times, "It's all math -- the number of calories burned and the number of calories consumed."
According to data just published in the online journal Population Health Metrics, during the last 10 years, Americans have gotten more active in two-thirds of the nation's counties. They have also gotten fatter.
To take California as an example, the percentage of women in the state who get sufficient weekly exercise rose over the decade from 50.7 percent to 59.2 percent. For California men, the positive change was from 59.4 percent to 61.3 percent. Yet, at the same time, obesity rates rose in every California county.
Here's the math. A person can walk an extra mile every day. In a week, that will burn up 900 extra calories. If that person has just one meal consisting of a Big Mac, fries and a coke, he or she will consume 920 calories. One lunch negates all the extra miles.
The reality is, a person can exercise for hours every day, but calories are not easy to burn. What's easy is consuming them. It's not just visiting much-maligned McDonald's that can get a person in trouble, it's our entire processed food industry. Widespread obesity is a problem unique to our current era and will not disappear until we can shift away from convenient processed and packaged food and get closer to the way our grandparents and great grandparents ate.
Walking, running, lifting weights, riding bikes, swimming; all forms of exercise are good for your health. But eating a leaner diet is the only way to drop the pounds. It's a simple truth that is tough to accept -- take it from me, the guy who detoured to get a couple of Winchell's donuts this morning on my way to the newsroom.
Please, don't tell my trainer.
Two-time Pulitzer Prize winner David Horsey is a political commentator for the Los Angeles Times. Go to latimes.com/news/politics/topoftheticket/ to see more of his work.