Vitamin D deficiency and weight gain: are the two connected?

Medically reviewed by Neka Miller, PhD on February 15, 2021. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Could there be a connection between vitamin D deficiency and weight gain? That’s what we’re exploring in more depth here, so learn more about the possible link between the two below.

Check your vitamin D levels from the convenience of home with our easy-to-use vitamin D blood test. You just collect a small sample of blood (via a simple finger prick), send it to a lab for testing (a prepaid shipping label is included with the kit), and get digital results in days.

Understanding vitamin D

Vitamin D is a fat-soluble vitamin that naturally appears in a number of foods and has been added to others. While other vitamins can only be obtained via your diet, vitamin D is the only vitamin that the body can make on its own, though it requires the skin’s direct exposure to sunlight. Generally, combining sun exposure with a diet that contains rich sources of vitamin D allows you to maintain adequate levels and prevent deficiency.

Vitamin D plays a variety of roles in the body. It is perhaps most well-known for its role in bone health. Vitamin D allows for the proper metabolism and absorption of calcium, and the two work in conjunction to ensure normal bone mineralization and bone growth. Healthy levels of calcium and vitamin D also protect against osteoporosis and other bone issues.

Vitamin D is also used by the immune system and can contribute to basic immune function, like fighting off infections and potentially reducing inflammation. With this vitamin playing such vital roles in the body, a vitamin D deficiency can cause a number of unwanted health problems.

Vitamin D deficiency and weight gain

Having inadequate levels of vitamin D may correlate with unintentional weight gain. A study on women over the age of 65 found that participants with a lower vitamin D level experienced more weight gain.

A systematic review of 23 different studies found similar associations between vitamin D deficiency and obesity. The results of the review showed that vitamin D deficiency was about 35% higher in participants with obesity and 24% higher in participants who were overweight.

Related: Vitamin D vs. D3: What's the Difference?

Understanding the relationship between vitamin D and weight

More research is necessary to fully understand how vitamin D factors into weight gain in terms of actually contributing to increases in weight, if at all. After all, correlation is not causation, meaning that low vitamin D does not necessarily cause weight gain, nor does high vitamin D contribute to increased weight loss. That some studies show a relationship between low vitamin D and weight gain doesn’t mean that inadequate vitamin D levels are responsible for added weight. In fact, the opposite might be the case, in which having a greater weight increases one’s risk of vitamin D deficiency.

Some research suggests that vitamin D may play a role in how abdominal fat is stored and used, but beyond that, more studies are necessary to understand the connection. However, certain lifestyle factors—discussed below—may help shed more light on the relationship between vitamin D and weight gain.

General nutrition

Vitamin D is naturally found in fatty fish, egg yolks, and organ meats, and it is frequently added to fortified foods like milk, yogurt, breakfast cereals, and juices. Highly processed foods that contain added sugars usually do not contain much vitamin D. These foods also happen to be high in empty calories, which can contribute to weight gain. Note that if you are not getting enough vitamin D from your diet, vitamin D3 supplements and extra sunlight exposure can help to make up for your low levels [ref]. (It’s always a good idea to talk with your healthcare provider before trying out a new supplement.)

Getting too little exercise

As mentioned above, your body can make vitamin D on its own. This process starts when the sun’s ultraviolet rays hit your exposed skin. The exact effects of exposure can vary based on a wide range of factors, from cloud cover to your own skin color (more melanin often requires more sunlight exposure to produce vitamin D), but most experts recommend 10 to 30 minutes of direct exposure a few times per week.

There are plenty of reasons why you might not get enough sunlight, like your location and the time of year, but it may also coincide with an overall physically inactive (or “sedentary”) lifestyle. Less time spent outside often means less physical activity, which naturally contributes to more weight gain among some people.

Depression

Some studies suggest a link between vitamin D levels and depression. In one comprehensive review of the research on the matter, researchers found that adults with depression tended to have lower levels of vitamin D.

Depression can have severe effects on nearly all aspects of your health and well-being, even outside of your mood. Clinical depression is known to affect weight in many cases. For some people, this means a lack of an appetite that results in weight loss. In others, increased food cravings may result—particularly for sugar and carbs—which can contribute to increased weight gain.

That being said, keep in mind that the connection between vitamin D levels and depression is still under investigation, and more research will need to be carried out before researchers and medical experts have a clear understanding of the full picture.

Symptoms of vitamin D deficiency

Symptoms of vitamin D deficiency may include:

• General fatigue
• Bone pain
• Aches, cramps, and weakness in the muscles
• Depression and sudden mood changes

If it isn’t addressed, vitamin D deficiency can also contribute to a softening of the bones. In children, this is known as rickets and can cause problems in growth and development, as well as certain bone deformities. In adults, the softening of bones is known as osteomalacia, which can cause pain, discomfort, and changes in the way you walk.

(Wondering if your vitamin D levels might be too low? Check your vitamin D status easily with the Everlywell at-home Vitamin D Test.)

How much vitamin D do you need?

The specific amount of vitamin D you need will vary based on factors like your age. The recommended dietary allowance for most adults is 600 IUs (International Units) of vitamin D per day, while those older than 70 can take upwards of 800 IUs per day. You can get this from foods that are naturally rich in vitamin D, fortified foods, or dietary supplements—and, of course, through exposure to sunlight.

To see what your vitamin D levels are like, take the Everlywell Vitamin D Test—an easy at-home option that lets you conveniently collect a sample at home and send it to a lab for accurate testing (a prepaid shipping label is included with the kit).

References

1. Vitamin D. NIH, Office of Dietary Supplements. URL. Accessed February 15, 2021.

2. Cheng S, Massaro JM, Fox CS, Larson MG, Keyes MJ, McCabe EL, Robins SJ, O'Donnell CJ, Hoffmann U, Jacques PF, Booth SL, Vasan RS, Wolf M, Wang TJ. Adiposity, cardiometabolic risk, and vitamin D status: the Framingham Heart Study. Diabetes. 2010 Jan;59(1):242-8.

3. Depression (major depressive disorder). Mayo Clinic. URL. Accessed February 15, 2021.

4. Vitamin D Deficiency. Cleveland Clinic. URL. Accessed February 15, 2021.

5. Metabolic syndrome. Mayo Clinic. URL. Accessed February 15, 2021.

6. Obesity Linked to Lower Vitamin D Levels. WebMD. URL. Accessed February 15, 2021.

7. What are the risks of vitamin D deficiency?. Mayo Clinic. URL. Accessed February 15, 2021.