Teenage boys who sleep less have more body fat, but the same isn't true for adolescent girls, a new study has found.
Researchers in human nutrition at the University of Otago in New Zealand found that teenage boys who sleep less have
more body fat but sleep deprivation in girls has no
discernible effect on their body fat ratios.
The study looked at the sleeping habits and height/weight/fat ratios in 386 boys and 299 girls aged between 15 and 18-years drawn from 11 secondary schools around Otago.
Lead researcher Dr Paula Skidmore said significant results between sleep duration and body composition were found in boys, but not in girls.
An average-sized 16-year-old boy weighing 69.5 kg and measuring 176 cm in height, who slept for eight hours a day, would have a waist circumference that is 1.8 cm bigger, and would have 1.6 kg (9 per cent) more body fat, compared to the same average-sized boy who slept 10 hours a day, the study found.
"The boys who slept eight hours a day would also have 1.8 kg more lean (bone and muscle) mass compared to the boys who slept ten hours, but that's only a 1.4 per cent increase, compared to the 9 per cent increase seen in body fat," Skidmore said.
"Our results suggest that for older teenage boys, making sure that they get adequate sleep may help to maintain a healthier body. It seems to be that, within reason, the more (sleep) the better for boys.
"It was unexpected that we did not find the same result in girls, who may actually be more aware of their diet and more in tune with a healthier lifestyle," she said.
The study was published in Nutrition Journal.