Can Being Low in Vitamin D Cause Weight Gain?

Vitamin D supplements

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Vitamin D is a fat-soluble vitamin sometimes touted as a natural weight loss aid when taken as a dietary supplement. Indeed, some research suggests that running low on vitamin D might increase your risk of weight gain, while taking vitamin D supplements may help promote weight loss and weight maintenance.

What Is Vitamin D?

Vitamin D is an important nutrient that plays a role in many body functions, including helping to build stronger bones and better immunity. 

While vitamin D occurs naturally in some foods, such as oily fish, and is added to foods such as fortified milk and juice, most people's primary source of vitamin D is sun exposure. For some people, taking supplements may be a more reliable means of maintaining adequate vitamin D levels. People who are at risk of a vitamin D deficiency include:

  • Breastfed infants
  • Older adults
  • People who are overweight or obese
  • People who have had bariatric surgery (such as gastric bypass surgery)
  • People with limited sun exposure and those who frequently use sunblock
  • Those who live in northern latitudes
  • Those with darker skin tones

Essential for strong bones and osteoporosis prevention, vitamin D may also help reduce the risk of heart disease and boost the immune system.

Does Low Vitamin D Lead to Weight Gain?

There is some scientific evidence to suggest that being low in vitamin D may be associated with weight gain. For example, a 2019 study found an association between low vitamin D and "greater volumes of fat, serum, liver, and muscle present in obese people." However, the researchers could not conclude that obesity is a consequence of vitamin D deficiency since there are other contributing factors associated with weight gain to consider.

However, a large meta-analysis of nearly 30,000 studies published in Obesity Review in 2015 found that low vitamin D was associated with obesity regardless of age or latitudinal location. In particular, the prevalence of vitamin D deficiency was about 35% higher in obese subjects.

Another study published in 2019 in the International Journal of Obesity notes the global prevalence of vitamin D deficiency. It acknowledges a growing body of evidence that shows vitamin D supplementation can help treat people with obesity. The researchers suggest that the relationship between low vitamin D and obesity is clinically significant. Further investigation could lead to improvements in the treatment of obesity by healthcare professionals.

While there is a connection between obesity and being low in vitamin D, the nature of the relationship is not yet fully understood. More research is still needed to determine if normalizing vitamin D serum levels may lead to weight loss.

Vitamin D for Weight Loss

Several studies have examined the effects of vitamin D on weight loss. Supplements containing both vitamin D and calcium show the most promise. However, researchers have yet to determine whether taking vitamin D alone (rather than in combination with calcium) can help promote weight loss.

Improved Weight Loss Success

In a 2014 study published in the American Journal of Clinical Nutrition, researchers compared 12 months of vitamin D3 supplementation with a placebo in postmenopausal women in a weight loss intervention. At the study's end, women who had adequate blood levels of vitamin D had lost more weight and body fat and had a greater reduction in waist circumference.

In a 2010 study, researchers found that boosting levels of vitamin D (and intake of dairy-derived calcium) may increase the likelihood of weight loss while dieting. The study involved 126 overweight women, all of whom were followed for six months.

Prevention of Postmenopausal Weight Gain

Vitamin D may help prevent weight gain that often occurs among middle-aged women. In a study published in 2007, 36,282 postmenopausal women were assigned to receive vitamin D and calcium in supplement form or a placebo daily.

After three years, supplement-taking participants who had skimped on calcium prior to the study were found to be 11% less likely to gain weight (compared to those assigned to a placebo).

Lowered Cholesterol

Vitamin D supplementation may also enhance some positive effects of weight loss. In tests on 63 overweight or obese women assigned to a weight-loss program, scientists discovered that those who took 400 IUs of vitamin D and 1,200mg of calcium in supplement form daily during their 15-week diet had greater improvements in cholesterol levels (compared to those given a placebo for the same time period).

Research has found that losing weight also helps increase vitamin D levels in the body.  Being overweight is a risk factor for vitamin D deficiency, which suggests that the amount of vitamin D a person needs may depend on their body size. 

How Vitamin D May Prevent Weight Gain

There is some evidence to suggest that vitamin D can help prevent weight gain. For instance, a 2008 review suggests that vitamin D may be able to reduce the formation of new fat cells.

Another study published in 2012 found that vitamin D may help to promote satiety and appetite control to reduce overall calorie consumption. In addition, a randomized controlled trial published in 2011 showed that vitamin D increased testosterone levels in men, which is associated with increased metabolism and weight loss.

How Much Vitamin D Do You Need?

The National Institutes of Health (NIH) states that the recommended dietary allowance (RDA) for Vitamin D is 15 micrograms (mcg) or 600 international units (IUs) daily for healthy children and adults.

The body produces vitamin D naturally with sun exposure, and according to the NIH, there are few foods that naturally contain vitamin D to help you meet your RDA. Dietary sources of vitamin D include:

  • Fatty fish: Mackerel, cod liver oil, halibut, salmon, sardines, trout, and tuna
  • Animal protein: Beef, chicken, eggs, pork, turkey
  • Mushrooms: Wild mushrooms, some commercially grown mushrooms, and mushroom powders
  • Fortified foods: Breakfast cereals, milk and plant-based milk alternatives, and some brands of orange juice

Healthcare providers often suggest a vitamin D supplement for those who are deficient. In these cases, vitamin D supplements containing 1,000 IUs are often recommended.

How to Take Vitamin D Safely

Be aware that consuming an excessive amount of vitamin D may cause vomiting, loss of bone density, and other problems. Long-term or excessive intake of calcium supplements may also have adverse effects on health.

A research letter published in JAMA in 2017 tracked excessive vitamin D consumption (more than 1,000 or 4,000 IUs daily) of nearly 40,000 participants from 1999–2014. The study notes that vitamin D supplementation has increased significantly in recent years and warns of the potential adverse effects associated with excess vitamin D intake, which include kidney and bone problems.

While supplementing with 1,000 IUs is a common recommendation for vitamin D deficiency and is generally considered safe, taking more than 4,000 IUs increases the risks associated with excessive intake.

The safety of supplements in pregnant women, nursing mothers, children, and those with medical conditions or who are taking medications has not been established.

A Word From Verywell

Research suggests that increasing vitamin D intake could support weight loss efforts while enhancing overall health. In order to lose weight, it's important to combine vitamin D supplementation with a healthy diet and regular exercise program.

If you're considering vitamin D supplements, talk with your primary care provider first. Self-treating a condition and avoiding or delaying standard care may have serious consequences.

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