In case you missed the ruckus, 550 public health activists signed a letter last week demanding the forced retirement of Ronald McDonald. Apparently, this sinister figure is causing childhood obesity.

I hope you’ll laugh along with me at the idea that a clown character is making kids fat. But in a both serious and ridiculous way, it’s symbolic of the finger-pointing that pervades obesity politics.

Barely a week goes by without a new study “linking” something different to obesity. Recent research has blamed the following for contributing to the obesity epidemic: playing video games, fruit juice, caesarian sections, automobile use, snacks, baby bottles, eating breakfast, keeping the lights on, food eaten during pregnancy, pesticides, socioeconomic status, mothers’ full-time employment, depression, family violence, social relationships, school lunches, indoor heating, and capitalism.

There’s even a study that says simply seeing overweight people can cause weight gain. Kleenex and fax machines haven’t been linked to obesity yet, but give today’s “public health” movement a few years.

What’s the lesson here? First, there’s a lot of junk science masquerading as the real deal. And second, there’s not a lot the government can do to fight obesity. It’s up to individuals.

Weight gain is driven by people consuming more calories than they burn. And weight loss is the result of people burning more calories than they consume.

Simple, right? Just about everybody agrees.

Sadly, many “public health” researchers and activists can’t see the forest for the trees. They tend to focus their blame on soft drinks, fast-food restaurants, and a handful of other politically correct “causes” of obesity.

Take soda taxes for example. A Duke University study released in December determined that they’re not effective: A sizeable 20-percent tax on soft drinks would reduce the typical American’s daily caloric intake by only about 7 calories. The research also found that many consumers would just switch to other calorie-laden beverages instead of paying the tax.

And in 2008, the American Journal of Clinical Nutrition published a review of scientific evidence which shot down the very idea that soft drinks cause obesity in the first place. (It found no significant association between obesity and beverage consumption in kids.)

By demonizing a few foods, nanny-state activists are overlooking the large-scale, societal changes that have occurred over the past few decades.

For one, our jobs now require less physical labor. Research released last week from the Pennington Biomedical Research Center found that just 20 percent of jobs today require moderate physical activity. In 1960 that number was 50 percent. In the same time period, the typical amount of energy an American expends at work dropped by between 124 and 142 calories per day. For workers who don’t make up the difference outside the office, that adds up to 9 or 10 pounds of weight gain per year.

Fundamentally, we’re all less active than Americans were two or three generations ago. We have automatic dishwashers and washing machines. Between 1960 and 2000, driving to work became 38 percent more popular and walking to work declined by 70 percent.

It’s not that driving “causes” obesity, as some suggest. Like video games or fast food, cars can be part of a lifestyle that’s either healthy or unhealthy.

Public health activists and self-anointed “food cops” downplay this reality because, in the end, it would leave them with nothing to “fix” with legislation. Correctly recognizing that obesity is a matter of someone’s lifestyle would leave activists with two options: either invite government to regulate every facet of our lives, perhaps even dictating how much we all should weigh, or just admit they’ve run off the rails.

While no one should expect the latter, the former represents a draconian (and blatantly unconstitutional) approach. Incremental steps, taxing one food or drink at a time, are becoming progressively more intrusive. And the sooner Americans wise up to what these obesity activists are up to, the sooner all this clowning around will come to an end.

Rick Berman is President of the public affairs firm Berman and Company. He has worked extensively in the food and beverage industries for the past 30 years. To learn more, visit www.BermanCo.com.