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Obesity and vitamin D deficiency, which causes which?

Posted on: July 6, 2013   by  John Cannell, MD


Observational studies have consistently reported an increased risk of vitamin D deficiency in those who are obese. However, the underlying explanations and direction of causality are unclear. Does obesity cause vitamin D deficiency, does vitamin D deficiency cause obesity or is it a little of both?

Activated vitamin D (1,25-dihydroxyvitamin D) may influence the mobilization of free fatty acids from the adipose tissue as well as metabolism of fat cells. Rat experiments have shown that large doses of vitamin D lead to increases in energy expenditure, a mechanism of weight loss. However, three randomized controlled trials testing the effect of vitamin D supplementation on weight loss in obese or overweight individuals showed no effect. On the other hand, there have been randomized controlled trials that have shown a very modest weight reduction after vitamin D supplementation, too.

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6 Responses to Obesity and vitamin D deficiency, which causes which?

  1. Rita and Misty

    I did lose 30% of my body weight when I raised my 25(OH)D level from 32 ng/ml to 74 ng/ml…I did not change my diet, nor did I change my exercise patterns.

    I wonder (often) if my higher 25(OH)D level corrected a fairly sub-clinical thyroid problem…

    (awesome graphics, btw) πŸ™‚

  2. Magic

    I agree with the findings. I don’t think that D3 by itself is a weight loss miracle. Perhaps the obese are so embarrassed to be seen that it could be a contributing factor. (Never in the sun.)

    What happened to you has to be classified as a miracle, Rita. So many good things have happened to me that I have never included weight loss among them.

    At my age of almost 80 friends are dying at an alarming rate. None, however, that have been ingesting D3. Some doctors out here are still shocked when anything over 1000 D3 are mentioned.


  3. Rita and Misty

    Hi Magic,

    I think vitamin D can have a positive impact on the thyroid gland. And, my thyroid numbers were always in that (very slightly) hypo range. Supplementing with high doses of D improved the health of my thyroid.

    Plain and simple!!!

    Certainly, I do believe in miracles.

    For example, it was a miracle I found this awesome site and organization. I literally just fell onto the Vitamin D Council Facebook page (and my life has never been the same πŸ™‚ Really–Truly lol)

    But, I think my hormonal health improved because high doses of vitamin d made my thyroid gland healthy.

    Female hormonal healthy is directly related to a healthy thyroid–in my most humble opinion.


  4. IAW

    I agree with Dr. Cannell’s statement “It’s important to recognize that if you weigh more, you will need more vitamin D than someone who weighs less.” I am not convinced yet that “low vitamin d levels” cannot cause obesity to happen. Whether this is a director result or like Rita said an indirect improvement in thyroid function. We also know that a lot of studies use too small of an amount of Vitamin D to cause any noticeable or barely noticeable changes.

  5. Rita and Misty

    By the way: it takes quite a bit of gumption on my part to share my idiopathic early menopause health story with people; but I only hope that a few endocrinologists are reading me and perhaps will consider high dose supplementation for those patients diagnosed with such a condition.

    After my personal experience, I tend to believe there is no such thing as idiopathic early menopause….

    If I can keep just one woman from suffering how I suffered for six years I will be content.

  6. [email protected]

    I am 50 to 60lbs overweight. My work situation has made it difficult for me to loose those pounds. However, that has just changed. My D level is close to 60 ng/ml. I am 65 and no longer have chronic knee pain (no medical intervention). It will be much easier for me to be active again because I feel better. In turn that should help me loose weight.

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