Struggling With Weight Loss? Try Checking Your Vitamin D Levels

July 25, 2023

Maintaining a healthy weight and body composition can be challenging. Metabolic health is complicated and can be downright frustrating to manage. As it turns out, vitamin D has a pretty big role in metabolic health factors (bigger than you might think).

While it isn't often discussed, body composition has a profound impact on your body's ability to circulate vitamin D. This is because it's a fat-soluble vitamin, which means it's actually stored in body fat—and the more body fat a person has, the more vitamin D gets stored there.

How vitamin D status impacts body composition

As mindbodygreen's vice president of scientific affairs Ashley Jordan Ferira, Ph.D., RDN, explained in a previous article, "less serum vitamin D [aka, 25(OH)D], circulating in our blood means less D is available to our kidneys and other target tissues for conversion to its active, hormone form for its pleiotropic actions throughout our body." 

In other words, the higher an individual's adiposity, the more likely they are to have insufficient vitamin D levels. "And mind you, that's just one way that adiposity can compromise vitamin D status and its ability to do its widespread job in our bones, muscles, immune cells, brain, liver, etc.,"* Ferira adds.

Research shows there may also be a dilution factor and even metabolic differences for major vitamin D pathways in individuals with more adipose tissue (as measured by fat percentage, waist circumference, and BMI). Regardless of the exact mechanisms, the science shows a clear inverse relationship between adipose tissue and vitamin D status1.

In fact, vitamin D levels have been found to play a role in metabolic health factors ranging from weight loss and body composition to blood sugar balance and hunger hormone regulation:*

  • In a 2014 randomized controlled trial (RCT) published in the American Journal of Clinical Nutrition, postmenopausal women that achieved vitamin D sufficiency lost seven more pounds2, 2% more body fat, and four more centimeters of waist circumference, on average, than those with lower vitamin D levels. 
  • In a recent RCT from Menopause, healthy women between the ages of 50 and 65 who took a daily vitamin D supplement for nine months had healthier levels of adiponectin and leptin (i.e., adipokine hormones with a key role in body composition, insulin sensitivity, and healthy inflammatory actions) than women who did not.
  • In a 2012 study from the Journal of Women's Health, healthy women over 65 sufficient in vitamin D were found to gain less weight3 over a span of 4.5 years than those with vitamin D insufficiency.

The science doesn't lie: Vitamin D has a number of science-backed benefits supporting different metabolic health factors, including healthy body composition.*


The takeaway

Vitamin D and adiposity have a complex and nuanced relationship, and individuals with higher amounts of body fat may struggle to maintain healthy circulating levels of the fat-soluble vitamin.