Everyone knows what to do if they are gaining too much weight. Eat less, exercise more and most bodies will respond.

But what if it’s not just a few pounds we are gaining, but millions? What if it’s not just individuals getting fat, but the whole country?

A new study indicates that we better come up with an answer for that one and we better do it soon.

According to a report released Tuesday by the Trust for America’s Health, obesity rates are expected to climb. Every state is expected to have rates above 44 percent by 2030.

As the current heaviest state, Mississippi is projected to see more than two-thirds of its residents obese.

Maine, which has an obesity rate of 28 percent, is projected to see 55 percent of its population with a body mass index over 30, the line doctors draw to indicate where merely overweight turns into a serious medical condition.

If there were a virus that infected half of Mainers, we would expect the government to play a role in protecting our health.

We are facing an epidemic of bad choices that we all will end up paying for. We should be willing to invest now in heading off those costs.

Programs that educate people about nutrition, including those which provide consumers with calorie counts in restaurants and limits on portion size, will help. Health plans that reward people who take good care of themselves will also help.

More research into possible environmental causes, like the recent study that links childhood obesity and BPA, a chemical found in food packaging, may also make a difference.

But dealing with obesity is a problem for the entire society and treating it like it’s all individual choice will not solve it.