The state and country must do more to address today’s most significant public-health problem: obesity. When researchers know that, if current trends continue, more than half of all adults in Maine will be obese by 2030, policymakers and health professionals cannot stand still. Lowering the obesity rate will take many specific steps — and time. Nothing about it will be easy, not just because a person’s weight is affected by many different factors, but because it will require a new way of thinking and a reworking of how the food industry operates.

Increasing sedentary lifestyles and greater access to fatty, sugary foods, which often cost less per calorie than fruits and vegetables, have led to the obesity epidemic. A lack of incentives for both consumers and the medical profession to address the health threat have contributed to the problem. Studies of molecular genetics have helped the country understand eaters’ short- and long-term motivations and could help researchers develop drugs to fight obesity.

But the biggest changes will not come from a medicine for ending obesity. To effectively reverse the obesity rate, policies must address the principal causes.

One main cause of obesity has its roots in the overproduction of food. With the U.S. food supply generating about twice the number of calories the average adult needs each day, food companies compete for a greater share of the market through advertising, more “appealing” products and larger portion sizes, according to Marion Nestle, a professor of food studies and public health at New York University. The food companies prosper when people eat more.

The government can make it easier for people to make healthy choices and help structure the market to be more health-based. It can subsidize commodity crops less and fruit and vegetables more. It can require that foods bought and distributed in federal programs are healthy. It can work with schools to serve nutritious meals and snacks, as the National Prevention Council Action Plan proposes. It can place more restrictions on food marketing to children.

Employers can be proactive by implementing wellness programs — not just to help people become healthier but to reduce costs. Johnson & Johnson discovered that its wellness program saved the company $250 million on health care costs over 10 years. And schools have great power to instill good habits. Child obesity rates in Philadelphia dropped 5 percent over four years after the Philadelphia School Department eliminated sodas and sugary drinks from vending machines, developed snack standards, offered free breakfasts to all students, stopped using fryers and switched from 2 percent milk to 1 percent.

Of course weight is affected by many things, including genes. And there is evidence that it’s biologically difficult to drop pounds and keep them off because the body continues to fight against losing weight even after dieting has stopped — often causing hardworking, well-intentioned people who have lost weight to regain it. Discussion about reducing the obesity rate should never involve blame. Losing weight is difficult, and successfully doing so requires a change in lifestyle — not a quick fix. Everyone knows that weight loss requires eating less and exercising more; but actually doing it is a real challenge.

Policies should focus on prevention and create structures that encourage healthy behaviors. The recent analysis from Trust for America’s Health and and the Robert Wood Johnson Foundation found that states could dramatically reduce health care costs and prevent obesity-related diseases if residents reduced their average body mass index by just 5 percent by 2030. For a six-foot-tall person weighing 200 pounds, that represents about 10 pounds. It is possible to reduce obesity rates. But the longer states wait, the harder it will become.