The director of the Los Angeles County Department of Health Services believes that taxing junk food and sugary beverages is one way to encourage people to eat more healthfully. - 

David Lazarus: More than one in three adults in America is considered obese, and the obesity epidemic has contributed to a steady increase in health care costs. We're constantly told to eat right and get some exercise. But that doesn't seem to be cutting it. Some say we need to put our money where our mouths are and use financial incentives to change people's eating habits.

Commentator and doctor Mitchell Katz says it's time to serve up a tax on junk food.

Mitchell Katz: The United States is suffering from an epidemic of obesity and diabetes. These two related epidemics are shortening our life span and causing tremendous suffering and economic loss.

The solution is for all of us to eat a better diet -- one that's high in fruits, vegetables, whole grains, and fiber and low on concentrated sweets and saturated fats. We also need to get more exercise. The problem is that it's hard for people to consistently follow these recommendations.

One reason is our society has produced perverse economic incentives. Over time, the cost of sugar-sweetened beverages has gotten less expensive compared to the costs of more healthful choices, like milk. In other words, our economic system makes the logical choice a big glass of soda instead of a big glass of milk.

Here is where there's tremendous value in instituting a surcharge, or tax, on junk food and sugary drinks. By increasing the cost, we make it easier for people to make the more healthful choice. The tax money can be used to increase awareness about the harm of junk food and fund projects that encourage better choices.

Copying a successful tactic of anti-tobacco crusaders, the funds could also be used to counter the lavish advertising of soda and junk food by "marketing" alternatives like apples or ordinary tap water.

A common criticism of the surcharge is that it alone will not change obesity and diabetes rates. This is probably true. It's going to take many different interventions. We should eliminate farm subsidies for corn production, which make the corn syrup in sweetened beverages so cheap. We need to increase the number of farmers' markets and provide zoning incentives to place supermarkets in low-income neighborhoods so people can buy good food at an affordable price. Improving school lunches and re-instituting physical education will also help.

No one strategy will end the twin epidemics of obesity and diabetes. But a surcharge on junk food is one promising strategy to make it easier for people to make the healthy choice.

Lazarus: Dr. Mitchell Katz is director of the Los Angeles County Department of Health Services.