If you’re about to celebrate the first month of keeping your New Year’s resolution to lose weight, you’re one of the lucky ones. Surveys show that by Feb. 1, more than a third of the 100 million Americans who made the initial commitment will have already given up on their diets, or failed to meet their weight loss goals.

And lawmakers from New York to Massachusetts, and in Minneapolis and St. Paul, have been making their own 2009 resolutions: Regulate our diets through taxation and prohibition.

But unsuccessful dieters and overzealous policymakers might consider that they might have been focusing on the wrong side of the weight-loss equation.

State-by-state obesity statistics suggest a lack of physical activity, not food and drink, is more responsible for our expanding waistlines.

Obesity rates vary among the states, even though Americans can buy the same soda and the same hamburgers in all 50. With only a fifth of its residents officially fat, Colorado is the leanest state, while Mississippians, a third of whomare obese, are the fattest. Do people in Mississippi really have the biggest appetites?

Of course not, as Wichita Eagle food editor Joe Stumpe observed. On the Kansas journalist’s recent visit to Colorado, he noticed the state had all the usual fast-food eateries. So why is Colorado leaner than Kansas? Stumpe concluded that the answer “does appear to involve walking, running, skiing, boating, biking and a host of other physical activities. Colorado residents just seem to be more active than people in a lot of other states.”

This insight was echoed by James Hill, cofounder of the National Weight Control Registry. Hill suggests people’s failure to get trimmer can be attributed in large part to our narrow, food-only approach. “We focus too much on diet and not enough on physical activity,” he says.

Indeed, of the 10 most obese states, government surveys show nine of them are also the most sedentary. Coincidentally, the residents of the most obese state, Mississippi, report the lowest rates of leisure-time physical activity in the country.

Are fast-food outlets too numerous? Census statistics indicate that none of the 10 obese states have the most fast-food restaurants per person. In fact, Mississippi is third-lowest in the country in fast food density. Colorado, the leanest state, ranks in the top 10 in fast food concentration.

This reality is mirrored by scholarly studies. A 2007 study published in the International Journal of Obesity concludes: “The obesity epidemic is often speculatively blamed on fast food, when the actual evidence shows very little, if any, association of fast food with weight gain.”

As for soft drinks, West Virginia had a tax on “handling or distribution of all bottled soft drinks and all soft drink syrups” for more than five decades.

According to the federal government’s rankings, the state is the fifth most obese in the nation.

While there is no clear relationship between soft drinks or fast-food restaurants and obesity, there is an unambiguous relationship between physical inactivity and obesity in the United States. Unfortunately, as the Centers for Disease Control and Prevention reported recently, 43 percent of Americans get less exercise than the federal government’s 2010 recommendation.

Arbitrarily regulating foods, drinks and ingredients is much easier than regulating sedentary lifestyles. But that won’t change the scientific facts about weight loss. Data tell us the nutritional content of our meals is virtually unchanged from a half century ago, but fewer of us are burning off the calories we consume.

So let Feb. 1 be the beginning of a new, meaningful resolution that takes a lesson from Mississippi and Colorado: Have a soft drink with lunch, or a hamburger for dinner — but don’t forget to go for a walk or run afterward. If they can do it in Denver, so can you.