Is Weight Gain Linked to a Vitamin D Deficiency?

Vitamin D has become a focal point in the medical and nutrition industries. Unlike any other vitamin, vitamin D acts more like a hormone than a vitamin inside the body. It is involved in many physiological pathways and has been linked to the prevention of multiple chronic diseases, including osteoporosis and breast cancer.

In 2009, research began to investigate the correlation between weight gain and vitamin D deficiency.  At that time, scientists found a connection, but remained uncertain if it was lack of vitamin D that caused the weight gain or excess weight that caused a lack of vitamin D.

Today, researchers know that a vitamin D deficiency creates an interference with leptin, the hormone responsible for signaling the brain that you are full and need to discontinue eating. In modern society, many overweight individuals fail to spend an adequate amount of time outdoors, exposed to sunlight – the best source for pre-vitamin D. This, combined with overeating and a lack of physical activity, can lead to continued weight gain and obesity.

If you have been diagnosed with a vitamin D deficiency or are concerned that you may be deficient or become deficient, consider spending 15 minutes outdoors, in the sunlight without SPF or clothing covering the majority of your arms, neck and back (less time is necessary for fair-skinned individuals and more time may be necessary for darker-skinned individuals.) Please note that SPF reduces absorption of vitamin D by 90 percent, but a mere 15 minutes daily is all that is necessary for most individuals. Pre-vitamin D is absorbed by the skin from UV rays of sunlight.  Once in the skin, vitamin D is transported and converted to the readily usable form – vitamin D3 – inside the liver.  It is then transported for use throughout the body – nearly every tissue in the body has receptors for vitamin D.

Many experts and doctors recommend vitamin D supplements to remedy a deficiency, however no long-term studies have proven this to be effective. Vitamin D supplements – do not offer superior bioavailability of vitamin D.  However, experts, who question the effectiveness of these supplements, agree that it “can’t hurt” to supplement. Some food manufacturers have begun treating certain types of mushrooms to provide vitamin D3, but even the bioavailability of vitamin D in these products is questionable.

Fatty fish, such as salmon or tuna contain vitamin D, but primarily vitamin D2 – the less bioavailable form. Dairy products, certain cereals and orange juice have been fortified with vitamin D2, but deficiency rates have remained high, making these products lacking effectiveness as a remedy for deficiency.

Areas of the country with little to no sunlight during many parts of the year should consider a diet that is rich in fatty fish and fortified foods, as well as supplements – being certain to choose supplements offering vitamin D3. For now, this plan offers the best solution to deficiency, although not as effective as routine exposure to natural sunlight.

If you are overweight or obese, moderate, routine sunlight exposure combined with a balanced diet and exercise may improve your weight loss success. Remember, vitamin D is a fat soluble vitamin – excess fat drives vitamin D to be stored throughout the numerous fat cells in the body, causing an inadvertent depletion of serum vitamin D throughout the body. In this case, weight loss and healthy weight management is necessary to maintain healthy levels of vitamin D.

Ask your doctor for a screening to detect vitamin D deficiency. Low levels are not only associated with weight gain, but colorectal cancer, high blood pressure, kidney disease and bone fractures. Early stages of a long-term study by the National Institutes of Health suggest adequate levels of vitamin D may be connected to prevention of heart disease, stroke and cancer in individuals with no prior history of such diseases.

This was a question from a follower on my Facebook page. Feel free to send me your nutrition and fitness related questions on Facebook or at



  1. What a great blog site! I stumbled across your latest post and it’s very interesting to me because I am severely deficient in Vitamin D (my bloodwork in Feb showed 10)… I’ve been spending more time outside as part of this major transformational journey I’m on to lose weight and it’s already up to 27! I’ve lost 33 pounds and 43 inches recently and I’m glad to see that my Vitamin D levels are going up as I spend more time outside as well as lose weight.. Would love some more support on my blog site so take a look when you get a chance: / Cheers, HIBA

  2. […] D.  Taking 65 units of vitamin D per pound of body weight daily for one to two weeks has been shown to boost […]

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