When a flurry of studies came out in the early 2000s revealing the weight-loss powers of vitamin D, health experts were buzzing. It seemed scientists had finally discovered a miracle pill that would help us slim without struggle. Flash-forward to 2015: Millions of women took vitamin D daily and when the scale barely budged, they were left to wonder if the news was just hype.
Experts knew the previous studies hadn’t been a fluke, so why weren’t women losing weight? Scientists at the Fred Hutchinson Cancer Research Center in Seattle have finally found the answer. In a double-blind trial, postmenopausal women were broken into two groups: One took a placebo daily; the other took 2,000 IUs of vitamin D. Why 2,000 IU? “At the time we began the study, that was the maximum amount the Institute of Medicine recommended without close medical follow-up.