Weight loss comes down to the simple formula of calories in calories out, right? Not so fast. For many of us, weight loss is not that simple. There may be an underlying issue hindering weight loss that we need to address, such as a low functioning thyroid or an imbalance in hormone levels.

Research is now suggesting we need to look more closely at vitamin D as a potential weight loss inhibitor. Vitamin D is beyond a vitamin; it actually functions as a hormone and is referred to as “Hormone D.”e. The active form of vitamin D is structurally similar to other steroid hormones in the body, and it can be produced in the skin as long as sunlight exposure is adequate.1 This sets vitamin D apart from other vitamins.

Vitamin D deficiency

Vitamin D’s benefits go beyond calcium absorption and bone health. Several other organs and tissues in the body use vitamin D: the heart, stomach, brain, liver, skin, thyroid, parathyroid, pancreas, immune system cells, and the adrenal glands.1

Research has clearly shown that an insufficient level of vitamin D alters many cellular functions and is associated with chronic conditions including type 1 diabetes, hypertension, multiple sclerosis, and several types of cancers (breast, prostate, and colon). Vitamin D deficiency may predispose one to type 2 diabetes. 2

So, what about weight loss?

In a study done by McGill et al. it was shown that there was an inverse relationship between serum (blood level) vitamin D3 and weight, body mass Index, and type 2 diabetes.3 Thus, a lower vitamin D level was related with a higher body weight.

Other studies done on adults have shown an association between low vitamin D levels and higher body fat. Lenders et al. conducted a study on adolescents which revealed that a higher fat mass percentage was associated with a lower vitamin D level.4

It is thought that higher body fat leads to more sequestering of vitamin D in fat tissue (vitamin D is fat-soluble), and thus less vitamin D is available to be used by the cells of the body. Additionally, optimal functioning of the thyroid is needed for metabolism and weight loss. If a low vitamin D level is predisposing one to insulin resistance and diabetes, then the thyroid function can suffer.

The insulin surges that occur with insulin resistance (the cells are no longer responsive to insulin so the body secretes more and more) contributes to an inflammatory response that starts to destroy the thyroid gland. This then affects the production of the thyroid hormones.

Simply put, vitamin D helps balance blood sugars and insulin levels, which is one way to help the thyroid gland stay in top shape to support your weight loss!

What can you do from here to ensure your vitamin D level is sufficient?

Get your vitamin D level checked

The standard range for Vitamin D, 25-OH for most labs is 30-100 ng/mL. However, please keep in mind that the optimal range is between 50-70 ng/mL, which is the range for being in the best of health. Between 70-100 ng/mL is usually recommended for those with cancer or heart disease.

Assess whether you are getting in enough vitamin D through food and sunlight

Sunlight exposure is one way you can meet the vitamin D requirements, however, sunlight exposure is limited by several factors: weather, geographic location, the use of sunblock, and skin pigmentation.

Those with darker skin will need to be out in the sun for a longer period of time to absorb enough sunlight to produce vitamin D. From late October to early March, the UV rays are too weak to synthesize vitamin D north of 42 degrees latitude, which is about where Chicago is.

Even north of Atlanta, there are certain times of the year where sunlight exposure will not be strong enough to synthesize vitamin D.Some vitamin D can be obtained from the diet, but few foods naturally contain vitamin D.

vitamin d deficiency weight lossFood sources mainly come from animal products such as liver, egg yolks, and saltwater fish such as sardines, tuna, and salmon. Be sure you are eating a well-balanced diet that is composed of healthy fat, protein, and carbohydrates (I recommend consuming double the amount of vegetables than fruits and grains for the day to help keep blood sugars from soaring). For weight loss (and health!), it is important to keep your blood sugars stable and prevent a blood sugar-insulin roller coaster ride throughout your days.

Vitamin D supplements

You may want to discuss supplementation with your practitioner to see if that is an appropriate option for you.




Thacher TD, Clarke BL. Vitamin D insufficiecy. Mayo Clin Proc. 2011;86(1):50-60.
Palomer X, Clemente-Gonzalez JM, and Blanco-Vaca F. Role of vitamin D in pathogensis of type 2 diabetes mellitus. Diabetes, Obesity and Metabolism. 2008;10:185-197.
McGill A, Stewart JM, Lithander FE, Strik CM, Poppitt SD. Relationships of low serum vitamin D3 with anthropometry and markers of the metabolic syndrome and diabetes in overweight and obesity. Nutrition Journal. 2008;7:4.
Lenders CM, Feldman HA, Von Scheven E, et al. Relation of body fat indexes to vitamin D status and deficiency among obese adolescents. Am J Clin Nutr. 2009;90:459-67.
Wang L. Vitamin D. NYCC MSACN Program; Fall 2012.

WatchFit Experts change lives!

And they can do the same for you.


Pollyanna Hale Health and Lifestyle coaches
Lost 13 Kg in Total
Mel, 32y Location: London, United Kingdom Working with Pollyanna changed everything. I lost 13kg, got toned and have more energy than ever! Get same results!


Chriz Zaremba Fitness Consultant
Lost 45 Kg in Total
Chris, 50y Location: London, United Kingdom Lost 45kg after the age of 50 and now competes and wins physique competitions and runs marathons Check our weight loss plans