THE US Government told Americans for the first time yesterday that they must try to lose weight, conceding that obesity levels have reached crisis point.

In new dietary guidelines issued by the US Health Department, weight loss is, for the first time, listed as a top priority.

The guidelines follow studies showing that two thirds of Americans are now either obese or overweight. Tommy Thompson, the Health and Human Services Secretary, recently said that obesity would soon overtake smoking as the leading cause of preventable death in America.

The Government recommends that adults do between 60 and 90 minutes of moderate -to-vigorous exercise most days to sustain weight loss, and at least one hour to prevent weight gain — targets that one expert said were unrealistic. The earlier guidelines recommended only 30 minutes.

“Tonight, eat only half the dessert,” Mr Thompson said as he published the new guidelines, which are revised every five years. “And then go out and walk around the block. And if you’re going to watch television, get down and do ten push-ups and five sit-ups.”

He added: “Do you want to look better? Yes. Do you want to feel better? Yes. You lower your calorie intake, you lower your fats, your carbs. You eat more fruits and vegetables, more wholegrains and you exercise. That’s as simple as it can be. It is not too hard.”

Ann Veneman, the Agriculture Secretary, whose department is jointly responsible for the guidelines, said that the advice was nothing new to Americans but the estimated $42 billion (£22 billion) the public spends each year on diet books and products reflected a widespread desire to get healthier.

Other changes to the guidelines included a call for wholegrains to make up half the grains in diets — at least 3oz a day. Recommended daily servings of fruit and vegetables rose from five to nine. More low-fat dairy products were also recommended, with advice to consume three cups of low-fat or non-fat milk or yoghurt daily. Schools must follow the guidelines in lunch menus.

James Hill, an obesity expert at the Colorado Health Sciences Centre, said that an hour of exercise a day was too daunting. “We can’t even get people to do 15 minutes, and now we are asking them to do an hour,” he told USA Today.

David Katz, director of Yale University’s Prevention Research Centre, said that Mr Thompson did a disservice by saying that losing weight was not difficult. “What he should have said is that it’s not complicated. It’s not complicated, but it’s hard, and frankly too damn hard for most people. It’s time to recognise we need a toolkit: exactly what do I buy when I go shopping, exactly what do I order when I go out, how do I make good choices, how do I satisfy my kids?”

The Government also recommends keeping trans fat, which can clog the arteries, as low as possible. It is found in cakes, biscuits and crisps. The Government recommends keeping saturated fats at less than 10 per cent of calories, or 20g in a 2,000-calorie diet. Ideas for cutting its consumption include choosing low-fat cheese, extra- lean mincemeat and low-fat milk.

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