Statistics released this week show that 19.8 per cent of P1 pupils were overweight in the 2008-09 school year; another 8 per cent were obese and 3.9 per cent severely obese.
Children from deprived areas were more likely to have a high body mass index (BMI) in P1; 20 per cent of boys were classified as overweight (including 8.1 per cent obese and 4 per cent severely obese); this compares with 19.4 per cent of girls (including 8 per cent obese and 3.8 per cent severely obese).
In the least deprived areas, 16.7 per cent of P1 children were overweight, 6.2 per cent obese and 2.6 per cent severely obese, while in deprived areas, 21.2 per cent were overweight, 9.2 per cent obese and 4.7 per cent severely obese.
NHS Highland topped the league for P1 children - 24 per cent were overweight, 10 per cent obese and 5 per cent severely obese.
The Scottish Government admitted the figures were concerning, but they were an improvement on 2005-06 and brought the number of overweight children back in line with the figures for 2000-01.
Labour, however, called for faster progress and accused the SNP Government of reneging on its promise to deliver two hours of PE per week, free swimming and outdoor education.
Levels of low BMI remained relatively stable, with 3.4 per cent of P1s classified as underweight in the past year.
Meanwhile, other statistics published by ISD Scotland show prescriptions for Attention Deficit Hyperactivity Disorder (ADHD) increased threefold in eight years, from 21,750 in 2000 to 70,863 last year; five- to 14-year- olds were the likeliest group to be on medication.
NHS Fife was the largest single user of ADHD drugs last year with 247 prescribed items for every thousand children aged five to 14. The Scottish average for the same period was 125 prescribed items.