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UK researchers found that rapid growth in early life could speed up the resting metabolic rate in adulthood by up to 20 per cent, increasing the appetite for high-fat foods. This is the first study to show that early growth patterns could cause long-term differences in metabolic rate.

What is the research?
The reports are based on a UK study, which examined the effects of four different protein diets on the metabolic rates of zebra finches.

Zebra finches were chosen for the study as they have previously been shown to exhibit catch-up growth after early protein deprivation.

Finch chicks were randomly assigned to either a high protein (40 per cent) or low protein (12 per cent) diet for the first 15 days of life. The chicks were then randomly assigned to receive either a high protein or a low protein diet for a further 15 days. This created four different diet groups.

The diet provided from day 30 onwards until the chicks reached adulthood at day 200 was kept the same for all birds.

To examine the effects of the diets on growth patterns, wing length was measured with cal-lipers and body mass recorded using an electronic balance.

Researchers found that the birds that had been switched from a low protein diet to a high protein diet showed an accelerated increase in growth. As adults, their resting metabolic rate was 20 per cent faster than birds on the other diets.

No increases in growth or metabolic rate were seen in the other groups.

What do the researchers say?
Lead researcher Professor Neil Metcalfe, from the University of Glasgow, said: 'Improvements in diet early in life caused a change in metabolism as well as a short-lived spurt in growth.

'The metabolic difference might be produced by a change in the size or functioning of key organs in the body, which would have long-term consequences.'

This increase in metabolic rate could lead to an increase in appetite which could lead to obesity, he said.

What do other researchers say?
Tam Fry, chairman of the Child Growth Foundation, said: 'The growth patterns of finches and humans are just too different. You cannot extrapolate results from a study carried out in finches to humans.'

But obviously an unbalanced diet in childhood will lead to obesity, he added.

sanjay.tanday@haymarket.com

Proc R Soc B Online 2008

Informing patients

• Growth spurts in early life could increase the risk of obesity in adulthood.
• Resting metabolic rate was 20 per cent higher than average in adults who had growth spurts when young.
• Study was performed in birds not humans.