Mark Haub decided he was going on a diet. But rather than stocking up on salads and Slim-Fast, the Kansas State professor of nutrition decided to try something different: Twinkies, doughnuts and an occasional hot dog.

Here's the catch: He kept his daily food intake at 1,800 calories. He also exercised for 40 to 60 minutes every day.

Two months later, the results are in. Haub lost 27 pounds since he began the diet in August. His "good" cholesterol is up and his "bad" cholesterol is down. He even decided to stick to it.

You may remember Morgan Spurlock, who tried a different diet for his documentary "Super Size Me." Spurlock ate McDonald's at every meal for a month. He gained 24.5 pounds, his cholesterol exploded and he suffered health palpitations. But unlike Haub, Spurlock refused to exercise. He also consumed more than 5,000 calories per day.

Obviously, neither Haub's nor Spurlock's diets are advisable, let alone healthy. But in their extremes, they both prove the same point: Taking personal responsibility by watching what you eat and exercising is the best way to keep your weight down.

But personal responsibility is anathema to the cadre of public-health busybodies, like the Ralph Nader-inspired Center for Science in the Public Interest, which has convinced legislators that food, not lack of self-control or exercise, is responsible for obesity. San Francisco just passed a ban on Happy Meal toys. New York City Mayor Michael Bloomberg wants to force food-stamp recipients to give up soda.

But demonizing food doesn't make anyone healthier. As every yo-yo dieter will tell you, going cold turkey is a recipe for failure. No matter what food they're in, calories are just energy. Weight gain or loss is due to an imbalance between calories "in" (from food) and calories "out" (from physical activity). And more and more evidence is pointing to increasingly sedentary lifestyles over the past few decades as a big, fat reason our waistlines have expanded.

Sixty years ago, only 9 percent of American homes had a television set. Today, the average number of TVs in a home outnumbers the average number of people. Watching TV expends only slightly more energy than sleeping, which may explain why children with TVs in their bedrooms are 30 percent more likely to be obese.

From automatic garage-door openers and riding lawn mowers, to dishwashers and robots that vacuum the floor, nearly every physical aspect of our life has become automated, simplified or eliminated. But in exchange for that convenience, we've sacrificed nearly 200 calories each day. That's 73,000 extra calories a year that we aren't burning off.

And then there's the time we spend on the job. Over the past century, America's work force has transitioned from toiling in the field to sitting at computers in air-conditioned offices. The impact on our calorie imbalance shouldn't be underestimated. The average administrative assistant uses 102 calories per hour to complete office work. The average farmer, on the other hand, burns about 544 calories per hour shoveling hay.

And at the end of the day, most Americans hop in the car and drive home — even though every hour of driving per day increases your risk of obesity by 6 percent.

It's not as if "the good ol' days" were a bastion of healthy eating, either. The famous Twinkie was invented in 1930. The doughnut dates back to at least the 19th century. And the hot dog debuted in Germany in the 1480s.

The next time anti-food activists propose we limit or ban foods for "the public good," we should remind them that there are no "good" or "bad" foods, but there are fat-headed notions of how to fight obesity.