The Harvard School of Public Health recently released a 40-year study that links teenage obesity to MS. Researchers examined 238,000 women and discovered those who were obese during adolescence had twice the risk of developing MS compared to healthy 18-year-old women. Only adolescent body size mattered—the study found no correlation between childhood and adulthood body size. Almost 600 women were diagnosed with MS over the course of the study. High levels of vitamin D have been linked with a reduced risk of MS, and research shows that obesity is connected with low vitamin D levels in the body.