Thinking you are fat could lead to putting on weight © RexNorwegian researchers found that six in ten teenage girls who felt too fat despite being of normal size went on to become overweight in their twenties, compared with three in ten who had no weight issues.
Among healthy-sized boys, six in ten of those who had felt fat in their teens became overweight in their twenties but so did half of those who had been happy with their body size, according to the study in the Journal of Obesity.
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The stress of being unhappy with one's body, skipping meals such as breakfast and trying strict diets which prove too difficult to stick to could all lead to an increased risk of obesity, researchers said.
The team from the Norwegian University of Science and Technology used a survey of 1,200 normal weight adolescents aged 13 to 19, in which they were asked about their perception of their weight.
They compared the responses with a follow-up questionnaire eleven years later, examining how many had a Body Mass Index – a measure of weight relative to height – of 25kg per square metre (classed as "overweight") or 30kg per square metre and above ("obese").
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The researchers also carried out a similar analysis of participants' waistlines, with a waist of 80cm for women and 94cm for men qualifying as overweight, and measurements of 88cm and 102cm respectively classified as obese.
Researchers noticed that the young men and women who in their teens had described themselves as "chubby" or "very fat" were more likely to have become overweight or obese.
Some 59 per cent of girls and 63 per cent of boys who had incorrectly perceived themselves as fat went on to become overweight as adults (according to their BMI), compared with 31 per cent of girls and 48 per cent of boys who had been happy with their weight.
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When classed by waist measurement as opposed to BMI, 78 per cent of girls and 55 per cent of boys who had felt too heavy later became overweight, compared with 55 per cent of girls and 29 per cent of boys who had been unconcerned about their size as teenagers.
Previous studies have suggested that being anxious or stressed about one's body shape can cause weight gain, particularly around the waist, researchers said.
Teenagers who perceive themselves as overweight could resort to unhealthy eating habits, such as skipping breakfast, or adopting diets they cannot stick to, both of which are thought to raise the risk of becoming overweight.
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The scientists wrote: "Girls in particular tend to consider themselves as overweight, even though they are not, which may lead to psychosocial stress and unhealthy weight control practices such as skipping meals.
"This study demonstrates that the adolescents, classified as normal weight though perceiving themselves as overweight, have a larger weight gain into young adulthood than those who do not experience self-perceived overweight."
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