Your weight and your vitamin D levels may be linked, according to new research.
A recent study from the nonprofit Kaiser Permanente Center for Heath Research shows that women who have insufficient vitamin D levels are also more likely to gain about two pounds over a nearly five-year period, compared with people who have enough in the vitamin.
"Nearly 80 percent of women in our study had insufficient levels of Vitamin D," study researcher Dr. Erin LeBlanc, M.D., an endocrinologist and researcher at Kaiser, said in a statement. "A primary source of this important vitamin is sunlight, and as modern societies move indoors, continuous Vitamin D insufficiency may be contributing to chronic weight gain."
However, researchers cautioned that they only found a correlation -- and no proof that having low levels of vitamin D can actually cause women to put on the pounds. Therefore, they said to make sure to talk to a doctor before considering ways to increase vitamin D intake, like via a supplement, since everyone has different health concerns.
CNN explained why it's so important to get enough -- but not too much -- vitamin D:
Called the "sunshine vitamin" because most of us get it from the sun, vitamin D helps maintain our bones and muscles, and keeps our central nervous system in check. But if you take too much it could be toxic, causing nausea, vomiting and loss of appetite.
Currently, the Institute of Medicine recommends that people between ages 1 and 70 get 600 IUs of vitamin D every day, and people ages 70 and older get 800 IUs of vitamin D every day, WebMD reported.
Recently, the U.S. Preventive Services Task Force recommended that post-menopausal women who are healthy do not need to take vitamin D or calcium supplements for osteoporosis prevention, because there is not enough evidence that doing so can lower the risk of the disease.
The Journal of Women's Health study was conducted in about 4,600 older women, ages 65 and older. The researchers said that the majority of women in the study were not intentionally trying to shed pounds, although some of them did naturally as they aged. In fact, about 60 percent of the women in the study stayed within a 5 percent range of the weight at which they started the study.
After the study period, 12 percent of the women gained more than 5 percent of their body weight, while 27 percent lost that percentage of their body weight.
Researchers also found that nearly 80 percent of all the women in the study had less-than-sufficient levels of vitamin D, as determined by guidelines from the Endocrine Society (they had less than 30 nanograms of vitamin D per milliliter of blood). These women were more likely to have a higher starting weight than women whose vitamin D levels were considered sufficient (148.6 pounds, versus 141.6 pounds).
Researchers also found that among women who gained weight over the study period, the ones with insufficient vitamin D levels gained about two pounds more than women with sufficient vitamin D levels -- 18.5 pounds, versus 16.4 pounds.