Washington ? People who want to stay healthy need to exercise for at least an hour a day double the previous workout recommendation according to new dietary guidelines on fat, protein and carbohydrate intake.

Independent advisers to the government, in a report Thursday, avoided setting strict amounts for each of the three major components, proposing ranges so people can balance their diet.

“The ranges are new and were developed to assure a nutritionally adequate diet,” said Joanne R. Lupton of Texas A&M University, head of the Institute of Medicine committee that prepared the study.

The institute, for the first time, added an exercise recommendation to its dietary advice.

“To reduce some of the main killers of America we will have to increase the level of physical activity,” said Dr. Benjamin Caballero, director of the Center for Human Nutrition at Johns Hopkins University in Baltimore.

The committee recommended at least one hour of moderate physical activity daily, such as walking, slow swimming, leisurely bicycle riding or golfing without a cart. That’s twice the latest government guidance, recommended by the surgeon general in 1996.

Lupton said the committee recognizes that the lifestyles of many people might make this goal seem difficult to achieve. But Caballero noted that the exercise can be broken up and spread throughout the day.

In addition to recommending an hour of exercise daily for adults, the same amount was suggested for youngsters, and comes at a time when worry is increasing over the number of obese children.

Former Surgeon General David Satcher has organized a national summit of health and education experts next month to discuss ways to trim the fat from young people.

“We based our conclusions on the most scientifically compelling evidence,” said Lupton, who teaches nutrition. “We hope this report will guide policy-makers, health professionals and others.”

The report was prepared for government agencies that deal with health and nutrition in the United States and Canada. It could eventually lead to changes in food labels and government dietary recommendations.

The guidelines suggest getting 45 percent to 65 percent of calories from carbohydrates (sugars and starches found in such foods as fruit and bread); 20 percent to 35 percent from fat (meat, dairy products and oils); and 10 percent to 35 percent from protein (available from meat, eggs, dairy products and some vegetables). The protein recommendation is the same as in the past.