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Vitamin D Can Affect Your Weight: Here’s How

Medically reviewed by

E. P. Diamandis, MD, Ph.D


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Key takeaways

Vitamin D is a vital micronutrient that can mediate powerful health benefits, ranging from a more robust immune system to healthier, stronger teeth, muscles, and bones. That’s why all adults and children older than 12 months should get at least 600 IU of vitamin D every day from sun exposure, diet, and supplements -  although experts suggest that you should get more.

Vitamin D deficiency is quite common across the US and, in fact, the rest of the world. Roughly 1 billion individuals across the world have low vitamin D levels in their blood, according to a study published in the New England Journal of Medicine. What’s more serious, low vitamin D can contribute to various adverse health effects, including:

  • Fatigue
  • Tiredness
  • Frequent infections
  • Low bone density
  • Joint problems
  • Depression
  • Hair loss
  • Muscle pain
  • Impaired wound healing
  • And many others

It's recommended that if you believe to have any of the symptoms above, that you take a vitamin D deficiency test at home or, visit a physician for bloodwork to have a clearer insight on your existing levels.

Surprisingly, new research shows that vitamin D can also affect your weight. In this article we take a deep dive into the link between vitamin D and your weight, plus how vitamin supplements may be able to help you manage your weight.

What is vitamin D?

Vitamin D is an important vitamin that helps regulate the absorption of phosphate and calcium, two minerals that are necessary for healthy muscles, strong bones, and teeth. It occurs naturally in a small number of foods that include egg yolks, liver, red meat, and oily fish. You can also obtain this micronutrient in a variety of vitamin D-fortified food products like juices, buttery spreads, breakfast cereals, milk, and even non-dairy milk.

Vitamin D is often referred to as the sunshine vitamin, and understandably so. Your body naturally produces vitamin D from cholesterol (yes, you read that right!) when the sunlight’s UVB rays penetrate your skin. It’s recommended that people should get some exposure to sunlight every day - or at least a few days a week - so that you can naturally produce vitamin D in as little as 5 minutes in the sun.

Is vitamin D deficiency common?

For most people, it’s somewhat tricky to get enough amounts of vitamin D through diet or sun exposure alone. It is estimated that 41.6 percent of American adults are deficient in vitamin D. And this worrying figure can jump to 69% in Hispanics and up to a whopping 82% in African Americans, according to a 2011 analytic study published in the journal Natural Research.

Opting for supplements might be your best shot at meeting recommended daily intake (RDI). Taking dietary supplements helps you stay on top of your vitamin needs, especially during winter months and if you work and play mostly indoors.

Some groups are also more prone to low vitamin D levels than others, if you:

  • Are obese
  • Are overweight
  • Are elderly
  • Stay mostly indoors 24/7
  • Or use sunscreen when you venture out in the sunshine

You may be at increased risk of developing vitamin D deficiency. 

People who live in areas where they get little sun around the year and those who don't consume dairy/fish products should also consider vitamin D supplements. Studies have also shown that individuals with dark skin — especially those of South Asian, African-Caribbean, and African descent — are usually unable to obtain adequate amounts of vitamin D through sunshine.

Symptoms of vitamin D deficiency

But getting the proper recommended daily intake of vitamin D is essential, as deficiency can pose many negative health risks such as:

  • Vitamin D-deficient people often get sick — One of the biggest benefits of vitamin D is that it contributes to boosting your immune system, helping you keep disease-causing bacteria, viruses, and other pathogens at bay. That’s because this powerful micronutrient interacts directly with B-cells, T-cells, and other cells that fight off infection. If you can’t seem to shake off common illnesses, particularly flu and colds, from season to season, vitamin D deficiency could be to blame. Several extensive observational studies have found a potential connection between low vitamin D and respiratory infections, such as pneumonia, bronchitis, and colds.
  • Fatigue — Excessive tiredness and fatigue certainly have many potential causes, but low vitamin D is often overlooked as a possible culprit. One 2015 study showed that vitamin D deficiency could be an unusual link to chronic fatigue.
  • Lower back pain and bone pain — It’s been known for a long time that vitamin D plays a key role in bone strength and overall health. It’s not surprising that lower back pain, often accompanied by bone pain, may be associated with low levels of this vitamin, as noted by this 2015 observational study conducted in India.
  • Mood problems, depression, and anxiety — Some studies, like this 2013 meta-analysis and systematic review study, have noted a correlation between low vitamin D and depression, especially in older adults.
  • Other issues - Long-term vitamin D deficiency can also result in low-bone mass density, non-stress-related hair loss, unexplained muscle pain, and impaired wound healing.

How does vitamin D help your body?

Vitamin D has been lauded as one of the most beneficial micronutrients, and it does live up to the hype. It has been found to offer a variety of health benefits, including:

1. Vitamin D bolsters immunity and helps you fight disease

One of vitamin D's best-known benefits includes keeping your immune system robust, so you can fend off bacteria and viruses that cause disease. As mentioned, it is directly involved with disease-fighting cells, such as T-cells and B-cells, so it's in the middle of the action.

If you become sick or get infections frequently, a lack of vitamin D might be one of the major contributors. A few large observational studies have pointed out that its deficiency may be linked to certain respiratory tract infections, such as pneumonia, bronchitis, colds, flu, and even the chronic lung disorder COPD.

Supporting research has also noted significant improvement in these ailments when someone takes vitamin D supplements. For instance, a 2010 study published in the American Journal of Clinical Nutrition showed that vitamin D may help minimize your chances of getting the flu.

Another 2008 research paper appearing in the journal Circulation concluded that this vitamin may reduce your odds of developing cardiovascular disease. The sunshine vitamin may also help prevent severe COPD flare-ups, multiple sclerosis, and respiratory tract infections.

2. It promotes intestinal absorption of phosphorus and calcium

Calcium is a vital mineral for bone formation and health. It must be absorbed from the food and drinks we consume, but our digestive system isn’t built to get the job done alone. That’s where you can count on vitamin D to shine.

It’s worth mentioning again that adequate levels of the vitamin can boost absorption of calcium from the 10-15% range to as high as 40%. That is, without a doubt, impressive for a vitamin-cum-hormone. As if that isn’t remarkable in its own right, it also helps retain calcium that would otherwise be flushed out by the kidneys.

Vitamin D also plays a substantial role in maintaining healthy levels of phosphorus in the bloodstream. Like calcium, phosphorus is critical for maintaining strong and healthy muscles, bones, and teeth.

3. It supports healthy pregnancy

Pregnancy can be tricky if you are deficient in certain vitamins, and vitamin D is one of them. A 2019 review study revealed that pregnant women with low vitamin D are at an increased risk for preterm birth, preeclampsia, and other pregnancy complications.

Physicians also generally agree that vitamin D deficiency during pregnancy can put women at a greater risk of developing bacterial vaginosis and gestational diabetes. Because low vitamin and weight gain are often associated, it may also play a role in reducing pregnancy-related obesity and its complications.

4. It promotes oral health

Since it improves the absorption of calcium and phosphorus, vitamin D may help support oral health and hygiene. It achieves this by promoting the formation of strong and healthy teeth, as well as lowering the risk of gum disease, tooth decay, and periodontitis.

In a 2011 review study published in the Journal of the Tennessee Dental Association, dental experts and researchers noted that vitamin D can be beneficial for oral health because of its bone metabolism effects. This conclusion was also drawn from vitamin D's capacity to encourage the release of antimicrobial peptides and its anti-inflammatory properties.

5. It helps ward off anxiety, depression, and mood issues

Nervousness, anxiety, and depressed mood can sometimes be attributed to low vitamin D and weight gain. Review research, including this 2016 study appearing in the Journal of Affective Disorders, has shown a strong relationship between depression and vitamin D deficiency, especially in the elderly.

In another study published in the journal Clinical Rheumatology, researchers saw a common trend in which fibromyalgia patients experiencing depression and anxiety were more likely to have low vitamin D.

The good news

Further research has revealed that vitamin D may actually help stave off depression, alleviate anxiety, and regulate mood. For example, a cross-sectional study carried out by researchers at the University Hospital of North Norway showed that people with depressed mood noted a significant improvement when they received vitamin D supplements.

Vitamin D deficiency and weight gain

While research into low vitamin D and weight gain is still in its early stages, many intriguing connections have been seen.

First, being obese or overweight is in itself a risk factor for vitamin D deficiency. Research has shown that a higher body fat percentage and BMI (body mass index) may be linked to lower vitamin D levels in the blood. Experts have several theories for this. Some assert that overweight and obese individuals are likely to eat foods that do not contain the vitamin. Others suggest that obese people tend to stay mostly indoors and often cover most of their skin, which can limit vitamin D derivation from the sunlight.

At the same time, vitamin D deficiency can lead to weight gain in several ways:

Vitamin D deficiency and fatigue

Fatigue is one of the silent, underlying contributors to weight gain. And it is sometimes attributed to hypothyroidism, especially in middle-aged people or older, in whom the thyroid gland at times stops functioning effectively, potentially causing fatigue and weight gain.

With low levels of thyroid hormones in the blood, you will likely experience slowed metabolism and likely put on weight. Vitamin D deficiency, however, is often ignored as a potential cause of tiredness and fatigue, which can leave you without energy and motivation to work out or stick to your weight loss routine.

Vitamin D deficiency and loss of bone density

As we've mentioned repeatedly, the vitamin plays a paramount role in bone health by increasing the absorption of phosphorus and calcium. Low bone density is often related to low vitamin D levels, and so are other bone disorders like osteoporosis.

Loss of bone density not only puts you at risk of fractures, bone pain, and joint issues, it can also make it difficult to lose weight or stay active. Take osteoporosis, for instance: it limits your ability to walk, jog, run, play, and perform other forms of exercise. For older people, this may be the crucial link between their low vitamin D and weight gain.

Low vitamin D and weight gain and depression

There’s a well-documented relationship between depression, low metabolism, and poor weight management. Depression and stress may be signs of untreated vitamin D deficiencies. In a 2017 review study published online in the journal Neuropsychology, scientists noted a significant link between low vitamin D levels and depression. The researchers warned that further research is needed to define how vitamin D deficiency leads to depression. This may help explain the relationship between low vitamin D and weight gain, particularly in older adults and people who suffer from chronic health problems.

On a more positive note, taking vitamin D supplements can help improve someone's mood and ward off depression. This has been supported to a certain degree by controlled studies. In one 2009 study, for instance, researchers concluded that treating people with low vitamin D with supplements helps improve their mood and reduce depressive symptoms.

The bottom line on vitamin D and weight gain

Vitamin D deficiency can indirectly cause weight gain by increasing depression, instigating bone mass loss, and causing tiredness or fatigue. However, the jury is still out on how or whether the vitamin deficiency causes weight gain. In other words, while there is a correlation between vitamin D deficiency and weight gain, there is not necessarily a causative relationship between them.

A highly-quoted 2019 Medicinia study has shown that making lifestyle changes through exercise, healthy eating, etc. can be the first course of action that will address both vitamin D deficiency and obesity-based dysmetabolic state (often associated with metabolic syndrome). A handful of studies over the last decade have indicated that women with low vitamin D levels were more likely to gain weight than women with normal vitamin D.

Most research groups that target the topic of low vitamin D and weight gain often refer to a study presented at the European Society of Endocrinology in 2018. The researchers found that a larger waistline and higher body fat in both men and women was associated with vitamin D deficiency.

Can vitamin D help you lose weight?

The correlation between low vitamin D and weight gain is unquestionable. But can vitamin D help you shed some weight and perhaps keep it off? If evidence from a series of recent studies is something to go by, then yes — vitamin D supplementation can indeed improve your likelihood of losing weight and decreasing body/belly fat.

In one double-blinded study involving 218 obese and overweight female participants, all of whom were on an exercise program and calorie-limited diet, 114 were given a vitamin D supplement while the rest was the control group. At the end of the 12-month study, scientists discovered that participants who met their vitamin D requirements lost more weight (around 7 lbs.) than those who had lower-than-required blood levels.

The findings of the above study were backed by another 2018 clinical trial whose results were published in the International Journal of Preventive Medicine. In this study in which similarly obese and overweight women were put on a vitamin D supplement treatment for six weeks, researchers noted a significant reduction in the BMIs, waist circumference, and overall weight.

Scientific corroboration

Together, these studies reiterated an earlier assumption about low vitamin D and weight gain. In particular, they suggest that vitamin D supplementation may, as part of a weight loss regimen combined with exercise, improve the chances of weight loss success.

The weight-loss benefits of vitamin D seem to increase dramatically when the supplements contain both calcium and vitamin D. Researchers are yet to conclusively determine if vitamin D alone can work the magic.

The role of hormones

Given the potential connection between low vitamin D and weight gain, some scientists believe that the micronutrient may help increase the serotonin levels in the brain. This is often regarded as the "feel-good" hormone, and it is a neurotransmitter that is often linked to a plethora of biological functions like appetite, sleep, mood, and even stress centers. When your serotonin levels spike, you are more energized, invigorated, and motivated to stick to your healthy eating, exercising, and weight-loss routines.

Higher levels of vitamin D may also be related to increased levels of testosterone. This is a well-known hormone that promotes muscle mass, strength, and flexibility. It’s also thought to rev up metabolism, which could help you burn more calories and drop some pounds.

Some researchers theorize that vitamin D may prevent new fat cells from forming and increase levels of serotonin, a brain chemical that’s associated with appetite.

The advantage of lowering blood cholesterol

Having a high concentration of LDL (commonly referred to as the “bad cholesterol”) in your blood can not only increase your risk of developing heart disease, stroke, diabetes, and cancer, it can also make it difficult to lose weight.

Recent research has demonstrated that taking vitamin D supplements can have a positive impact on blood cholesterol levels. In one specific medical study that was published in the American Journal of Clinical Nutrition, researchers followed the cholesterol tests of obese and overweight women on a weight-loss plan for 15 weeks. Their findings showed that women who supplemented with a daily dose of 1,200 mg calcium and 400 IU of vitamin D experienced more improvement in cholesterol levels than those in the placebo group.

Vitamin D can help prevent post-menopausal weight gain

Most middle-aged women typically struggle with two beasts of the post-menopausal world: low vitamin D and weight gain.

Research has suggested that vitamin D supplements may play a role in thwarting post-menopausal weight gain. After three years of this 2007 extensive study, women who were given calcium and vitamin D supplements and stuck to their supplementation routine saw an 11% weight gain prevention advantage over those who were assigned to the placebo group.

How much vitamin D should I take to lose weight?

While we know that Vitamin D can affect your weight, there is no fast route to weight loss - even using Vitamin D supplementation. However, in order to reach optimal health, and thus a healthy weight - it’s important to supplement Vitamin D until you are no longer deficient. 

If you don’t currently know your Vitamin D levels, you can easily check at home using an imaware™ at-home Vitamin D test. You’ll receive results within 5-7 business days that can help you understand if you need to supplement your diet with Vitamin D. 

The general rule of thumb is that adults aged between 19 and 70 should take no less than 15 micrograms (which is roughly equivalent to 600 IU) of vitamin D daily. That should help fill the gap left by inadequate dietary intake and address your low vitamin and weight gain problem.

When using vitamin D supplements, it may be more prudent to tweak your dosage based on your body size and composition. Plausible research suggests a daily dosing rate of between 32 to 36 IU per pound of body weight. 

Remember, just like most vitamins, Vitamin D toxicity can happen so you should check with your physician to see how long you should supplement and with how much.


Can vitamin D supplements help you lose weight? A raft of studies seems to suggest a correlation, but not causation. Researchers attribute this to a variety of things like drop in blood cholesterol, stronger bones, and stress/depression reduction produced by vitamin D supplementation. Hormones like testosterone and serotonin might also have something to do with it.

Updated on
October 21, 2021
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