Added sugars in foods should make up less than 10 percent of daily calories, said US government dietary guidelines issued Thursday that for the first time urged specific limits on sweets. Saturated fats should also make up less than 10 percent of a day’s food intake, said the guidelines which are released every five years by the US Department of Agriculture and the Department of Health and Human Services. Doctors and some consumer groups hailed the guidelines as an important step forward in a nation where more than one-third of adults — nearly 79 million people — are obese.