What Getting Enough Vitamin D Really Does For Weight Loss

Health professionals agree that vitamin D is a beneficial nutrient that people may not receive enough of, despite having a readily available source in sunlight. Now researchers are exploring the "intricate relationship" between vitamin D and weight, with different studies noting that vitamin D may reduce weight gain or decrease body fat (via Healthline).

Vitamin D helps the body absorb calcium, reduces inflammation, and enhances the immune system. Combined with calcium, it helps protect children from developing rickets (a condition of brittle bones), and guards against osteoporosis in adults (via the National Institutes of Health). 

Adults ages 19 to 70 should get at least 600 IU (15 mcg) of vitamin D daily; those ages 71 and older should intake at least 800 IU (20 mcg). But many people have trouble reaching these amounts, the National Institutes of Health (NIH) say. That's why a number of foods, particularly breakfast cereals, orange juice, and non-dairy milk products such as soy milk and almond milk are fortified with vitamin D.

Our bodies naturally manufacture vitamin D when our skin is directly exposed to the sun. Yet, medical experts caution against too much sun exposure because the sun's UV rays can cause skin cancer. The NIH recommends limiting direct sun exposure, and applying sunscreen and staying covered up, which of course could easily lead to you not getting your full daily dose of vitamin D. Basking in sunlight through a window won't do the trick, either, experts say (via the NIH).

Seek vitamin D through supplements, fortified foods, and fish

While researchers haven't confirmed a definitive relationship between vitamin D and weight loss, several studies have found intriguing results. One study that followed 4,600 women over the age of 65 for four and a half years noticed that subjects who used higher levels of vitamin D gained less weight. This is worth noting because, as we age, our weight typically increases in accordance with factors such as a slower metabolism (via the Journal of Women's Health).

A separate 12-week study of 77 participants classified as "healthy overweight and obese women" observed a reduction in body fat among those who took vitamin D3 supplements compared to those in a placebo group (via the National Library of Medicine). In addition, a study following 165 men for one year found that those receiving vitamin D supplements had higher levels of testosterone than the control group. Several studies show that higher testosterone levels can sustain long-term weight loss and reduce body fat (via Healthline).

Some researchers speculate that vitamin D may influence weight loss because it can increase levels of the neurotransmitter serotonin, which can play a part in controlling your appetite. While scientists continue to sort this out, they advise against taking vitamin D in amounts greater than 4,000 IU per day, as excessive vitamin D can be toxic (via Healthline). Look for supplements such as D2 (ergocalciferol) and D3 (cholecalciferol), which increase vitamin D in the blood, and foods such as salmon, tuna, mackerel, egg yolks, beef liver, and fortified dairy products (via the NIH).