The Skinny on Vitamin D, the Sun, and Weight Loss

With daylight savings time bringing more sunshine into our day (thank goodness!) it reminds me of a question I was recently asked about whether vitamin D can help with weight loss.   Lots of hoo-ha about Vitamin D lately.   Vitamins seem to be taking their turns in the spotlight, eh?   First there was Vitamin C, kicking everything from scurvy to the common cold, even if the latter is more based on wishful thinking than scientific evidence… but hey, look at the market for Vitamin C-laced cough drops, cold-kicking concoctions, and even candy!  (insert cash register noise)  Then Vitamin A’s cousin Lycopene, found in tomatoes and strawberries, stole the show temporarily with studies revealing its association with reduced risk for cancer and heart disease.  Even ketchup companies slapped the LYCOPENE! sticker on their bottles to make us temporarily forget about the high fructose corn syrup and salt.  Ketchup to reduce heart attacks?   Nice try, Heinz.  But now Vitamin D is taking the lead in the vitamin race.  Vitamin D is often referred to as the “sunshine” vitamin because one form of vitamin D (D3) is made in the skin via a reaction that occurs with exposure to sunlight (AKA, ultraviolet radiation, UVR).  Vitamin D can also be found in fortified dairy products (milk, yogurt), dietary supplements, as well as naturally in fatty fish (salmon, tuna) and eggs.  Vitamin D is necessary for the body to absorb calcium (which is why milk is always fortified with it), and integral to bone health.  Lately though, much ado has been going on about vitamin D’s impact on almost every aspect of human health, including obesity.  Vitamin D “champion” Dr. Michael Holick out of Boston University heads up the hype on vitamin D with his best-selling book, The Vitamin D Solution which purports that Vitamin D “is absolutely needed to prevent and treat our chronic disease epidemic including heart disease, cancer, diabetes, depression, obesity, and autoimmune disease” per a blurb on his website. Of course, as an obesity expert, I am intrigued by the claims regarding the treatment of obesity. Let’s look further into the research on this topic….

The hype began when several observational studies reported an association between vitamin D deficiency and obesity, such that heavier people have lower levels of vitamin D in their blood.  One reason for this is that vitamin D is fat soluble. The more body fat that you have the more that vitamin D will be dissolved and stored in fat rather than available in blood.  This doesn’t mean that people with more fat have LESS vitamin D, just that their blood has less vitamin D.  Whether vitamin D stored in fat is less “active” is still up for debate.  (Please see Reddy and Gilchrest 2010).

Let’s assume for the sake of argument that vitamin D stored in fat is less “active” than vitamin D in the blood and that the “deficiency” found in people with higher body weights is real.  Does this mean that vitamin D supplementation (via food, supplements or the sun) will help REDUCE body weight?

I reviewed the literature going back 10 years and found only 2 trials that have directly tested this question.  In one of the trials by Zitterman and colleagues (2007), people in a weight loss program were randomized to placebo or vitamin D supplement (83 microgm/dl) and followed for a year.  The vitamin D group did not lose more weight than the placebo group, but they did have greater decreases in triglycerides, which is good news.  The bad news is that their LDL-C (“bad”) cholesterol (a risk factor for heart disease) significant INCREASED compared to the placebo group.  Hmmm….  A second study by Major and colleagues (2009) randomized people in a 14-week weight loss program to a supplement containing calcium plus vitamin D or a placebo and found no differences in weight loss between groups.  They did find an advantage in the calcium/vitamin D group on HDL (good cholesterol) and HDL:LDL ratio, which is good news.  With only 2 studies and both showing no impact on weight, where is the hype that vitamin D helps with weight loss coming from???   Well, there are a few studies that show that the amount of weight someone loses in a weight loss program is associated with increases in serum vitamin D.  (See Shahir and Miller studies below)  I do not interpret these findings as vitamin D causing the weight loss but rather possibly that as people are reducing their weight (fat mass), their serum vitamin D rises (less fat for the vitamin D to get absorbed into) OR that healthier diet is what is causing the weight loss and vitamin D along with other nutrients increase in people who improve their diets.

The bottom line is that I see NO compelling evidence that increasing your vitamin D will at all help you to lose weight.  Vitamin D does appear to be essential to bone health and if you are at all at risk for osteoporosis, you should speak to your physician about identifying and correcting a deficiency.

Let’s go back to the issue of the sun.  Should we be tanning to lose weight?  The 2 studies I mentioned above tested the effects of vitamin D dietary supplements on weight.  Dr. Holick, vitamin D champion, suggests that much larger amounts of vitamin D can be had from sun exposure.  He recommends direct sun exposure on legs and arms 5-10 minutes three times a week at midday in the spring and summer and use of artificial sources (tanning booths) in the winter when UVR from the sun is not strong enough or available enough to generate adequate vitamin D (  His recommendations are an object of much debate given that UVR is a known carcinogen (definition:  cancer causing agent), and overexposure is associated with melanoma (skin cancer).  In fact, UVR (let me remind you that “R” stands for “radiation”) from tanning booths has been assigned the status of Class 1 carcinogen by the International Agency for Research on Cancer. Other Class 1 carcinogens include arsenic, radon, and mustard gas.  I personally will be no more likely to use a tanning booth for weight control than I would to use sweet-tasting arsenic as a sugar substitute in my coffee. I should also note that Dr. Holick receives funds for his research from the UV Foundation which is sponsored by….wait for it…. the Indoor Tanning Association.

Rats!  Now my summer plans of laying in the sun, eating ketchup by the spoonful, and popping vitamin C candies in the name of health are spoiled!

I guess at the end of every search for new weight loss solutions, we always end up in the same place… healthy diet and physically active lifestyle…



Lagunova Z, Porojnicu AC, Lindberg FA, Aksnes L, Moan J. Vitamin D status in Norwegian children and adolescents with excess body weight. Pediatr Diabetes. 2011 Mar;12(2):120-6.

Reddy KK, Gilchrest BA. J Invest Dermatol. 2010 Feb;130(2):321-6. What is all this commotion about vitamin D?

Zittermann, A., Frisch, S., Berthold, HK, Gotting, C., Kuhn, J., Kleesiek, K., Stehle, P., Koertke, H., Koerfer, R. Vitamin D supplementation enhances the beneficial effects of weight loss on cardiovascular disease risk markers. American J of Clin Nut, 2009, 89(5); 1321-7.

Shahar DR, Schwarzfuchs D, Fraser D, Vardi H, Thiery J, Fiedler GM, Blüher M, Stumvoll M, Stampfer MJ, Shai I; DIRECT Group. Dairy calcium intake, serum vitamin D, and successful weight loss. Am J Clin Nutr. 2010 Nov;92(5):1017-22.

Major, GC, Alarie, F, Dore, J., Phouttama, S, Tremblay, A. Supplementation with calcium + vitamin D enhances the beneficial effect of weight loss on plasma lipid and lipoprotein concentrations. Am J Clin Nutr. 2007 Jan;85(1):54-9.

Miller, GD. Improved nutrient intake in older obese adults undergoing a structured diet and exercise intentional weight loss program. J Nutr Health Aging. 2010 Jun;14(6):461-6.

El Ghissassi F, Baan R, Straif K, Grosse Y, Secretan B, Bouvard V, et al. A review of human carcinogens–part D: Radiation. Lancet Oncol 2009;10(8):751-752.

International Agency for Research on Cancer Working Group. The association of use of sunbeds with cutaneous malignant melanoma and other skin cancers: A systematic review. Int J Cancer 2006;120(5):1116-1222.


Zittermann, A., Frisch, S., Berthold, HK, Gotting, C., Kuhn, J., Kleesiek, K., Stehle, P., Koertke, H., Koerfer, R. Vitamin D supplementation enhances the beneficial effects of weight loss on cardiovascular disease risk markers. American J of Clin Nut, 2009, 89(5); 1321-7.

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  1. Mike b says:

    Thanks sherry for more good information. I also have to give you props to anyone that can work scurvy into an attricle. I love hearing when studies support who funded it, make me laugh everytime.

  2. Barb,RN says:

    Living in the “sunshine state”, I can attest to the fact that Vitamin D (the sunshine vitamin) does not help you lose weight.However Vitamin D does so many good things, how can you not like it? It promotes longer life with fewer diseases and fewer infections, strengthens bones and muscles and it decreases pain, inflammation and depression. All these promote more enjoyment of life.And not only that, you can add a little healthy color to your skin while you’re getting a dose of Vitamin D. It also helps with the absorption of calcium and phosphorus so take calcium and Vitamin D supplements to prevent osteoporosis. And that’s the “skinny” on Vitamin D, my favorite vitamin.

  3. ABSOLUTELY, tanning beds can make you lose weight! My daughter Jaime used tanning beds daily when in high school/college until she was diagnosed with melanoma at age 20. While going through chemo for several years, she was vomiting constantly, and while going through radiation, her throat was burned so bad that she could not swallow … and she lost a lot of weight. By the time she died 9 years later, she was only skin and bone. Size 0 pants would fall off her. So does the use of tanning beds cause weight loss? … it certainly can. But do I recommend it? … definitely not. The dangers of tanning bed use are real, and my Jaime would tell you if she could that no tan is worth dying for!

  4. Sherry says:

    Donna, I’m so sorry to hear about your daughter. In my mind, no loss could possibly be greater. Thank you for sharing the story because the dangers of tanning are VERY real and far too often underestimated. I’m appalled that Dr. Holick recommends tanning beds for vitamin D, it is one of the MOST irresponsible health recommendations by a physician I have ever heard in my life. I’m so glad you have posted.


  5. Deana says:

    I just want to point out that 5-10 minutes 3x/week is a lot different than the amount needed to get a deep, dark tan. I don’t have any experience with tanning beds (as a fair skinned person who burns easily and likes my pale pallor) so I don’t know how long one stays in them.

    Also, keep in mind that D3 is synthesized as a result of UV-B exposure, not UV-A. There are treatments for those of us with dangerously low VitD levels that involve bulbs that produce only UV-B rays. They really do work. And really, rickets is a heck of a disease. Something that impacts ones life as much as melanoma, so don’t dismiss low VitD levels as being nothing.

  6. Jade says:

    My daughter is 12 and has low vitamin d she is also a bit heavyweight so is it true that if you take lots of vitamin d you will lose weight. Please I need answers

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