Can Vitamin D Deficiency Cause You to Gain Weight?

Vitamin D is the sunshine vitamin! Your body produces it when your skin is exposed to the sun. You can also get Vitamin D from your diet, although sadly only a few foods contain significant amounts of it.

Experts estimate that around 50% of people worldwide have suboptimal Vitamin D levels, while up to 1 billion experience a Vitamin D deficiency. It is almost impossible to get enough Vitamin D from diet and sun exposure.

Maintaining optimal Vitamin D levels is crucial for the health of your immune system, bones, and brain. It has also been suggested that adequate Vitamin D levels may help prevent unwanted weight gain.

Is there a link between low Vitamin D levels and weight gain?

People who are overweight or obese appear more likely to have low Vitamin D levels as compared with people with within the “normal” body mass index (BMI) range. This has caused some to suggest that low Vitamin D levels may cause weight gain.

A few studies seem to support this theory. In one study, women were given 1,000 IU (25 mcg) of Vitamin D or a placebo each day for 12 weeks.

By the end of the study, women in the Vitamin D group lost 5.9 pounds of fat, compared with around 1.1 pounds for those in the placebo group.

The women in the Vitamin D group also gained 3.1 pounds more muscle than those in the placebo group. Yet, there were no significant changes in waist circumference or total body weight.

Similarly, a recent review of 11 weight loss studies suggested that supplementing with 25,000–600,000 IU (625–15,000 mcg) of Vitamin D monthly for 1–12 months may reduce BMI and waist circumference in those who are overweight or obese.

However, these changes remain very small and no significant differences in total body weight were noted. The current research suggests that consuming higher amounts of Vitamin D has little effect on weight gain or loss. Bummer, that would’ve been an easy fix!!

So why do people who are overweight or obese have lower Vitamin D levels?

Currently, most researchers believe that the lower Vitamin D levels observed in people who are overweight or obese may be explained by other factors.

For instance, since Vitamin D is stored in fatty tissues, people with larger amounts of body fat need greater amounts of Vitamin D to maintain blood levels similar to those of people of lower body weight.

People who are overweight or obese may also spend less time outdoors or eat less Vitamin D rich or fortified foods.

Experts suggest that people who are overweight may need 1.5 times more Vitamin D than individuals with BMIs in the “normal” range to maintain similar blood levels, whereas people who are obese may require 2–3 times more.

How can I tell if I have a Vitamin D deficiency?

Over time, suboptimal sun exposure or low amounts of Vitamin-D-rich foods in your diet may cause you to develop a Vitamin D deficiency.

Vitamin D deficiency isn’t typically associated with noticeable symptoms unless the deficiency is severe, so most people don’t know they’re deficient until they have a blood test. However, prolonged, severe deficiency can result in the following symptoms:

bone pain or deformities
stress fractures
rickets (softening or weakening of your bones)
seizures
muscle spasms
dental problems
heart disease and stroke

If you recognize any of the above symptoms, make sure to discuss them with your doctor to rule out a Vitamin D deficiency.

Who is more at risk of a Vitamin D deficiency?

Although a Vitamin D deficiency can affect anyone, certain groups of people may be at a greater risk.

For instance, people who have had weight loss surgery may have a reduced ability to absorb Vitamin D from their diet, which may put them at higher risk of developing a Vitamin D deficiency.

This also appears to be true for people with other gastrointestinal disease like inflammatory bowel syndrome (IBS), celiac disease, short bowel syndrome, fibrosis, or chronic pancreatic insufficiency.

Older individuals, as well as those who have darker skin tones or spend little time outdoors, may likewise have an increased risk of deficiency due to a reduced ability to produce sufficient Vitamin D from sun exposure alone.

As discussed, Vitamin D deficiency is more common in people who are overweight or obese.

Finally, certain prescription medications may accelerate Vitamin D breakdown in the body, in turn, possibly increasing the risk of Vitamin D deficiency.

When should you get your Vitamin D levels tested?

If you suspect you may have low Vitamin D levels, consider getting your blood levels tested to rule out a Vitamin D deficiency, especially women over 40!

Optimal blood levels tend to fall within the 30–100 ng/mL range. Values below 20 ng/mL are usually defined as a mild deficiency, and those below 10 ng/mL are considered a moderate deficiency. Vitamin D levels below 5 ng/mL are considered a severe deficiency.

Most doctors recommend that you get your blood Vitamin D levels tested twice per year — once in the spring and once again in the fall. This will help you evaluate your current Vitamin D levels in relation to your sun exposure and tailor your Vitamin D intake or supplement regimen accordingly.

How can you improve your Vitamin D levels?

There are many ways to improve your Vitamin D levels.

Sun exposure

Your body can produce this vitamin from cholesterol when your skin is exposed to ultraviolet B (UVB) sun rays.

According to experts, exposing around 40% of your skin for at least 20 minutes to the midday sun, without wearing sunscreen, is sufficient for most people to produce enough Vitamin D.

However, those with darker complexions or living more than 35 degrees above or below the equator may find it difficult to produce enough Vitamin D from the sun alone. Smog levels, cloud cover, altitude, and the season are other influencing factors to consider.

Moreover, most dermatologists warn against excess sun exposure due to the increased risk of skin cancer linked to excess UV radiation.

What about diet and supplements?

The reasons described above make it important to ensure you include Vitamin-D-rich or Vitamin-D-fortified foods in your diet. Some examples include fatty fish, mushrooms, fortified milk, eggs, liver, and other meats.

The reference daily intake (RDI) for Vitamin D is currently set at 600 IU per day for adults, and 800 IU per day for pregnant women.

However, some experts argue that these recommendations are far too low to maintain optimal Vitamin D levels.

If you’re unable to maintain adequate blood Vitamin D levels through sunshine and diet alone, a supplement providing 800–5,000 IU of vitamin D may be needed.

Keep in mind that vitamin D is a fat-soluble vitamin, which means that taking excessive amounts over long periods may cause it to accumulate in your tissues up to levels that can be toxic.

Although vitamin D toxicity is rare, taking extremely high doses of Vitamin D over prolonged periods may result in dangerous side effects. This can result in nausea, vomiting, muscle weakness, pain, poor appetite, dehydration, brain disturbances, heart and kidney problems, and in severe cases, even death.

The best way to avoid Vitamin D toxicity is to monitor your blood vitamin D levels by getting them checked before and during supplementation, as well as working with your doctor to adjust the dosage accordingly. Most will also suggest a calcium supplement in anyone over the age of forty. You can take them together.

The bottom line

A Vitamin D deficiency is unlikely to cause you to gain weight, but if you are overweight or obese you do need more than the average weight person. Low Vitamin D levels may cause health problems or unpleasant symptoms, which are worth avoiding.

You can maintain adequate Vitamin D levels through a combination of limited sun exposure, a Vitamin-D-rich diet, and taking Vitamin D supplements.

If you suspect that you have low Vitamin D levels, go get a blood test to rule out a deficiency. Regularly doing so can also help you tailor your supplement regimen and reduce your risk of Vitamin D toxicity.