Teenage girls who are overweight or obese are significantly more likely to develop acne than their normal-weight peers, a new Norwegian survey suggests.
Researchers looked at whether weight, and more specifically body mass index (BMI, a ratio of weight to height), had any bearing on the onset of the common skin condition among teens.
Teens' responses to questionnaires focusing on acne history and weight suggested an association among girls but not boys.
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The reasons behind the link aren't clear, one expert said.
Overweight girls "may perceive their acne as being worse than it actually is, possibly due to self-image issues," said Dr Robert Kirsner, a professor and vice chairperson in the department of dermatology and cutaneous surgery at the University of Miami's Miller School of Medicine.
On the other hand, biology could play a role, said Kirsner, who was not involved with the study but is familiar with its findings.
"It is possible, but not yet known, that in girls, but not boys, excessive androgens caused by obesity has a greater additive effect on acne," he said. "It may be also possible that the psychological effect of being overweight in girls is greater than boys and thus leads to a more pronounced increase in stress hormones in girls, with acne as a consequence."
The Norwegian team led by author Dr Jon Anders Halvorsen, of the department of dermatology at Oslo University Hospital and the faculty at the University of Oslo, reports its findings Jan 16 in the Archives of Dermatology.
The authors point out that between 10% and 20% of teens struggle with moderate to severe acne, with many developing serious psychological issues revolving around poor self-esteem and difficulty socialising. At the same time, more and more children are falling prey to the so-called obesity epidemic.
To explore whether a connection could exist between the two, the investigating team conducted a survey involving roughly 3 600 Norwegians ages 18 and 19.
None of the participants was actively seeking out medical care at the study's launch. All provided their weight and height, and all reported on whether or not they had had pimples, and to what degree, the week before the study.
All responded to questions about drinking or smoking, history of mental distress and dietary habits - especially concerning sugar, sweets, chocolate, raw vegetables, fatty fish and potato chips.
Overweight was defined as having a BMI of 25 and up, while obesity referred to a BMI of 30 and up. Just under 10% of the girls and just over 15% of the boys were deemed overweight; fewer than 40 of either gender were classified as obese.
Different among boys
Overall, roughly 13% of all the girls were found to have acne. When looking solely at girls who were overweight or obese, however, this figure rose to almost 19%. The story was different among boys, with between 13% and 14% having acne regardless of their weight.
After accounting for an array of other possible factors that might affect acne risk, Halvorsen's team concluded that excess weight is associated with acne risk among teenage girls, but not boys.
It should be noted, though, that the study revealed an association between excess weight and acne, but did not prove cause-and-effect.
Dr Joel Gelfand, medical director of the department of dermatology clinical studies unit at the University of Pennsylvania in Philadelphia, described the effort as "very important", given the paucity of research in the field.
"There's not a lot of work out there understanding what the risk factors are for developing acne," he said. "And we're talking about a disease that affects virtually everyone at some point, and can have a devastating impact on a person's quality of life. So any work to better understand why people develop it and ways of preventing it – which we don't currently have – is of substantial importance."