Being unpopular in school will not only make your schooldays miserable, it could also make you more susceptible to diseases later on in life.

A new study, published in the journal PLoS One, found that teenagers who were ostracized in school are more likely to suffer health conditions like obesity, heart disease and diabetes in their early 40s.

The ill effects of an unhappy adolescence were particularly noticeable among the women in the study.

Researchers followed 881 students from northern Sweden for 27 years, from when they were 16 to 43. 

Researchers at the Umea University in Sweden asked teachers to rate how extroverted or introverted as well as how popular or unpopular the students were.

Participants were asked to take a series of medical tests when they turned 43, and researchers found that social isolation and unpopularity significantly predicted future metabolic syndrome, a cluster of health problems including obesity, high blood pressure, diabetes, bad blood fats and lack of ‘good’ cholesterol.

The findings also show that the more unpopular someone was in their adolescent years, the more likely they were to suffer from metabolic syndrome by the time they turned 43.

However, they stressed that it was not only people at “the extreme end of the spectrum”, like “those exposed to bullying or victimization” had worse health in middle age, but also those who were just slightly socially isolated also tended to have poorer health in later life.

“Our results support the notion that aspects of peer relationships are not only related to future health in the extreme end of the spectrum, e.g. restricted to those exposed to bullying or peer victimization, but that one’s difficulties with peers are represented by a health gradient in adulthood,” the authors wrote.

Researchers were unsure why the effect was magnified in females, but they suggest that an explanation could be because men and women had "different life course pathways".

"This is suggested by previous studies showing that socioeconomic circumstances largely explain the association in men only," they explained.  "Nevertheless, in the present study the association was in the same direction for both women and men, and the numerical difference in strength of association should not be overstated."

“Our results corroborate the general notion that peer relationships in childhood or adolescence may impact on adult health,” they concluded.

Researchers noted that there was still a strong link between unpopularity and poor health even after factors like the health of the participants at age 16 and their parent's social position were taken into account.