Arkansas is to launch America’s first state-wide compulsory fat-testing programme, which will alert parents if their child is obese.

The body-mass index (BMI) of each of the state’s 447,000 pupils will be calculated by health examiners and sent home on a report card, with leaflets on the health risks of being overweight, such as diabetes and heart disease.

The idea, according to the state legislature which approved it, is to nudge parents into making healthier choices and lifestyle changes for those who tip the scales too far. But critics say it amounts to interference and fear it could upset portly pupils and fuel taunts.

“Most homes have scales and mirrors and I think we can assume parents know what their kids look like,” said John Doyle, co-founder of the Centre for Consumer Freedom in Washington DC. He said efforts would be better spent providing sports. Only 31 per cent of Arkansas pupils participate in physical education.

However, state legislators, who worked with the Arkansas centre for health improvement to create the scheme, stress the report cards will be confidential and constructive. “It’s a tough thing being a child who is overweight, but we have to start somewhere and try to protect children,” said state House Speaker Herschel Cleveland.

One in four Arkansas high-school students and 9 per cent of the state’s children aged five and under are overweight. Rates of childhood Type 2 diabetes have soared by 800 per cent over the past decade.

Nationally, the number of overweight children has doubled over the past 20 years to 15 per cent.

* In New York City, all 1.1 million state-school students are being offered free breakfast in the hope of improving their learning potential.

The scheme is the first in America to grant a free meal to all children in a district regardless of their financial means. “When a kid comes to school without a decent meal in his or her stomach, they don’t learn anything so we’re wasting our money,” said city mayor Michael Bloomberg, whose administration has also just overhauled school menus to offer more nutritious foods and banned fizzy drinks in school vending machines.

The free breakfasts will cost New York City, the country’s largest school district, $500,000 (pound;314,000) a year, some of which will be raised by increasing the price of school lunch from $1 to $1.50 for those who can afford it.

Around 825,000 of the district’s pupils already qualify for free or subsidised school meals under the federally-funded school breakfast programme, yet only 14 per cent took up the chance for free breakfasts last year.

Officials hope that by expanding the scheme to rich and poor alike, the perceived stigma will be removed.