Studies Indicate There May Be a Link Between Vitamin D Levels and Weight


When it comes to the micronutrients that keep our bodies moving and in good health, vitamin D plays a significant role. It helps us metabolize fat-soluble vitamins, regulate hormones, absorb calcium, maintain bone health, keep our immune system running properly, and a whole lot more.

“It also helps reduce inflammation and modulates many proteins in processes which regulate cell growth and development as well as cell death,” explains registered dietitian nutritionist Taylor Engelke. “It is essential to the reduction of risk for depression and other mental health disorders as well.”

Recently, a number of studies have looked at whether vitamin D plays a role in weight gain and weight loss. To get to the bottom of it and find out if vitamin D deficiency contributes to weight gain, we reached out to some experts in the field of nutrition and medicine. Keep reading to find out what we learned.

Is There a Link Between Vitamin D and Weight Gain?

As of now, there isn’t a clear link showing that vitamin D contributes to weight loss or weight gain, but we do know that there is an association between low vitamin D levels and obesity. Given that vitamin D is fat soluble, this could be because people with obesity may require more vitamin D to achieve the same levels as people with normal weight.

“Although vitamin D status is usually lower in people who are overweight or obese, the science isn’t clear on whether or not vitamin D supplementation can assist with weight loss,” says Morgyn Clair, a registered dietitian nutritionist. “It is generally accepted that supplementing with vitamin D won’t assist with weight loss itself, but adequate vitamin D status may promote overall health which can include a healthy weight maintenance.”

In a study where overweight and obese women took vitamin D supplements for 12 weeks, results showed a decrease in body fat, but not weight loss. Another study shows that vitamin D may suppress the storage of fat cells in the body and may even protect against obesity.

As you can see, the research findings are a bit mixed right now, and further research is needed before we can declare any definitive statements about the link between vitamin D and weight.

Common Signs of Vitamin D Deficiency

Here are some signs and symptoms you may be deficient in vitamin D:

  • Increase in fatigue
  • Depression and other behavior changes
  • Unexplained bone and muscle pain
  • Muscle weakness
  • Muscle spasms
  • Hair loss
  • Poor bone health
  • Changes in the color or quality of your teeth (often as a result of calcium deficiency)

Keep in mind that many of these symptoms have multiple causes, and don’t definitively mean you have a vitamin D deficiency. If you are experiencing any of these symptoms, it’s a good idea to check in with your doctor.

How Much Vitamin D Do We Need?

If you’re concerned about your vitamin D levels, the best way to check them and prevent a deficiency is by getting a blood test. Without a blood test. If testing reveals that your vitamin D levels are below 20 ng/ml, this is considered low. Levels of 30 ng/ml through 100 ng/ml are considered normal and often don’t require intervention.

“In general, people can meet their vitamin D needs with 600-800 IU per day,” Clair says.

That said, some people are at a higher risk of vitamin D deficiency and may require more vitamin D than others, including through supplementation. These higher risk groups include older adults, people with dark skin, people with limited sun exposure, and those with conditions that limit fat absorption, such as Crohn’s disease, says Dr. Abisola Olulade, a board-certified family medicine physician at Sharp Rees-Stealy Medical Group.

Easy Ways to Increase Your Vitamin D Levels


One of the simplest ways to increase vitamin D levels in the body is by increasing your exposure to sunlight. “Sunlight is absorbed through the skin and the body is able to transform a hormone into usable vitamin D,” Englelke.

But to get an adequate amount of vitamin D from sunlight, “you’ll need between 15-30 minutes of exposure to the sun with at least 25% of your skin exposed without sunscreen,” says Dr. Casey Kelley, a physician and medical director at Case Integrative Health. “For most of North America, this is impossible during the winter, so it’s not surprising that studies routinely find 40-60% of us are deficient in vitamin D.”  Where things get tricky though, is that increased sun exposure also increases skin cancer risk. For that reason, Kelley reminds us that sunlight is a good source of vitamin D, but shouldn’t be your only source.

If you’re concerned about your vitamin D levels, consult your physician before you start increasing sun exposure without wearing sunscreen, as unprotected sun exposure increases your risk for skin cancer.


Eating foods rich in vitamin D is another great way to increase your vitamin D levels without taking supplements. Fatty fish like tuna, cod, mackerel and salmon are all good choices, as are dairy products like yogurt and cheese. Egg yolks and mushrooms work, too. “Daily amounts can be obtained with one serving of fatty fish alone, and with a diet that includes at least 5 servings of fruits and vegetables daily,” Clair says.


Sometimes, diet and sun exposure alone don’t cut it. In that case, supplements may be recommended. “It will take a lot of [vitamin D-rich] foods to move the needle, so if you have a deficiency, we typically prescribe supplements or injections,” Kelley says, pointing out that these are widely available and inexpensive. She recommends looking for brands that don’t contain a lot of fillers or extras added to the supplements. One important allergy note here: vitamin D often comes from lanolin ( a waxy substance that comes from sheep), so if you are vegan or allergic to wool, you’ll want to look for a vegan supplement.

The Takeaway

Scientific studies show an association between lower levels of vitamin D and higher body mass index and body fat percentage, but there isn’t yet a clear link showing that vitamin D contributes to weight gain or weight loss.

“Just increasing vitamin D by itself does not appear to help patients lose weight consistently,” Kelley says. “While it’s possible that correct vitamin D levels improve the impact of other weight-loss activities, vitamin D alone won’t necessarily cause weight loss.”

That said, we know that vitamin D has a ton of other health benefits, from boosting immunity to helping with calcium absorption and hormone regulation. So if you suspect your vitamin D levels might be low, ask your doctor for a blood test.

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