The United States Department of Agriculture has issued some new dietary guidelines to curb America's obesity crisis.

Nutritionists advise cutting back on salt, sugar and saturated fats in American diets. They also say people should be eating more fruits and vegetables.

The idea is to provide incentives to offer healthier products, said Prof. Linda Van Horn of Northwest University. Ideally, companies should take "key products and gradually, but deliberately reduce the sodium contents of those foods," she said.

"As the American palette gradually adjusts, those food products can remain front and center in the American diet but not contribute the excessive amounts of sugar, fats, and salt," she explained.

The latest guidelines are not much different from past recommendations.

"These represent the most aggressive and forward thinking guidelines," Van Horn added.

Experts say there is more urgency than ever that Americans should change their diet, because more evidence shows obesity and a sedentary lifestyle is linked with disease and increased medical costs.