Vitamin D is a fat-soluble vitamin that your body absorbs and stores to stay healthy. This essential vitamin helps the body retain minerals such as calcium, and the nutrient also helps prevent over-absorption of signaling chemicals such as the parathyroid hormone.
In addition, research has shown that vitamin D helps protect the immune system by shielding it from infections and viruses like influenza. Recently, scientists have discovered that blood and most of the organs and tissue within the body contain receptors for this nutrient.
This pathology has important implications for key parts of human anatomy like the circulatory system and the endocrine system. But perhaps the most exciting current research on this nutrient has been in the field of using vitamin D for weight loss.
How the Body Obtains Vitamin D
Your skin synthesizes vitamin D as a hormone while absorbing the ultraviolet (UV) rays of sunlight, and many dieticians encourage getting vitamin D as a nutrient from enriched or fortified foods. Since vitamin D does not occur naturally in many foods, some experts recommend obtaining the vitamin from natural supplements.
The risk of skin damage from sun exposure and ozone-layer depletion also causes many people to opt for vitamin-D pills and supplements instead of sunbathing. At the very minimum, most adults need at least 400–800 IU (or an average of 600 IU) of vitamin D each day. An even more popular recommendation is the intake of 1,000 to 2,000 IU every day to remain on the safe side.
Vitamin-D and Weight Loss
Disturbingly, the latest World Health Organization reports indicate that between 40 and 50 percent of the world's population do not get enough vitamin D. An estimated 1 billion people have severe vitamin-D deficiency (VDD).
Some populations are at greatest risk of acquiring this deficiency, including older individuals, breastfed babies, darker-skinned people, and people who live in latitudes with low sunlight. Unfortunately, people who are obese also have a greater risk of developing a vitamin-D deficiency. Inversely, research now suggests that consuming up to 4,000 IU of vitamin D can benefit weight loss.
A look at the top benefits of taking vitamin D for weight loss can help you make an informed decision on your fitness journey.
Vitamin D Helps Regulate Belly Fat
Researchers have hypothesized the low vitamin-D levels may contribute to obesity. Studies have shown that people with a body mass index (BMI) higher than 30 typically have systems low in vitamin D.
A University of Minnesota study found that since the body uses vitamin D as an environmental sensor, low levels of vitamin D tells the body to store extra energy for times of limited resources.
The body primarily stores this excess energy as fat. For many individuals, this excess fat accumulates around the waistline for easy access to the bloodstream through the digestive system.
A minimum of 20 ng/mL (nanograms per milliliter) level of vitamin D within the bloodstream can help the body counter this storage of excess belly fat and may help some individuals lose weight.
For example, a 2014 study in the American Journal of Clinical Nutrition found that women who maintained high vitamin-D blood levels and followed a strict diet and exercise routine lost an average of seven pounds more than women who did not have high vitamin-D blood levels.
Because the body processes vitamin D through the liver and sends it into the bloodstream, taking vitamin D for weight loss is one of the most promising ways to complement calorie restriction and daily exercise.
Healthy vitamin-D blood levels can also reduce adipogenesis (the formation of fat cells within the body). For example, a study in the Journal of Women's Health found that older women with higher vitamin-D levels experienced less weight gain over the course of five years.
Likewise, a study in Nutrition Journal found that overweight and obese women who took 1,000 IU of Vitamin D every day for 12 weeks lost a measurable amount of fat mass independent of other bodily changes.
The research found that stored vitamin D tells the hypothalamus to decrease the output of parathyroid hormone (PTH), a hormonal substance that may cause the body to hoard belly fat.
Similarly, a 2015 University of Milan study and a 2018 Leiden University study found that dieters who take vitamin D may experience greater measurable reductions around their waistlines than those who do not take vitamin D. If you struggle with keeping your waistline in check, you may wish to have a specialist check your blood vitamin-D levels and adjust supplementary intake accordingly.
Vitamin D Has Antioxidant and Anti-Inflammatory Benefits
As one of the 24 micronutrients necessary for survival, vitamin D affects genes within nearly every organ of your body. Vitamin D is responsible for the synthesis of numerous peptides that reduce stress and help the body fight off infection.
The nutrient also engages in molecular signaling to inhibit inflammatory substances from adhering to cell walls and causing stress and inflammation. In addition, the body's organs also have receptors that turn vitamin D into the activated or hormonal form known as calcitriol.
This hormonal version of vitamin D helps repair cells, fights oxidation, and may even increase longevity. Notably, many of the top antioxidant and anti-inflammatory foods (such as olive oil, spinach, walnuts, and salmon) are also great natural sources of vitamin D.
Vitamin D May Improve Lean Muscle Mass, Strength, and Bone Mineral Density
In addition to reducing belly fat, taking vitamin D for weight loss has important implications in musculoskeletal health. A 2017 study found that combining vitamin D with aerobic exercise and resistance training can result in more calorie loss than exercise alone.
Vitamin D may also help with energy output during strenuous workouts, and the nutrient can increase lean muscle mass over the course of a year. In men, vitamin D can greatly raise internal testosterone levels that prompt weight loss.
Along with exercise benefits, the body stores vitamin D and enables it to play an important role in muscle repair. Muscle tissue has special receptors for vitamin D that enable the nutrient to strengthen muscle fibers and help facilitate recovery from cellular damage.
For example, since the heart is a muscle, this organ also has special receptors for vitamin D. A study published in Circulation Journal found that people low in vitamin D are significantly more likely to develop cardiovascular disease. Therefore, taking vitamin D for weight loss also may help lower the rate of heart-disease risk markers like triglycerides.
Vitamin D may also inhibit the collection of scar tissue and fibroblasts following heart-related trauma. Overall, the vitamin can compound the benefits of cardiovascular workouts and benefit cardiovascular health.
The nutrient has other workout implications as well. Because there is an inverse relationship between internal vitamin D levels and mood swings, a lack of vitamin D can lead to muscle fatigue.
According to research, supplementing this essential nutrient may lead to greater stamina during exercise. The nutrient is also essential in the conversion of amino acid tryptophan into serotonin, a hormone greatly associated with an elevated mood and more energy.
Serotonin may also reduce intermittent feelings of uncontrollable hunger and increase the feelings of fullness after meals, protein shakes or snacking.
In addition, vitamin D may also help improve sleep and result in greater restfulness after a day of physical activity.
As an added bonus, vitamin D may reduce the release of cortisol, a stress hormone known to encourage the storage of belly fat. Since one of the main roles of vitamin D is to regulate and boost the absorption of calcium and phosphorous, the use of vitamin D can gradually increase bone density over time.
This bone density is not only important in the prevention of fractures - but it can also improve the bodily structure and overall fitness level.
Vitamin D Can Help Counteract the Effects of Insulin Resistance
Studies have shown that people with type II diabetes or who are at risk for the condition may increase insulin secretion through vitamin D intake. The nutrient can also help with the hunger and overeating associated with insulin resistance and metabolic syndrome.
A study at the University of California at Davis found that high vitamin D levels result in the release of the hormone leptin. This hormone tells the body that it is full and may improve insulin sensitivity toward healthier foods.
Vitamin D Has Helpful Implications for People Considering Gastric Bypass Surgery
Many people view gastric bypass surgery as a viable option for extreme weight loss. Also known as bariatric surgery, this procedure removes or restricts a large portion of the stomach and intestines. One of the problems with altering these organs is that it can significantly limit the amount of vitamin D absorbed from food.
In turn, this lack of vitamin D can lessen the long-term benefits of undergoing this surgery. Following the procedure, medical professionals may advise you to increase your vitamin D intake to help lower this risk of this deficiency.
Mason, C. et. al; Vitamin D3 supplementation during weight loss: a double-blind randomized controlled trial.; American Journal of Clinical Nutrition; https://www.ncbi.nlm.nih.gov/pubmed/24622804
LeBlanc, E. et al; Associations Between 25-Hydroxyvitamin D and Weight Gain in Elderly Women; Journal of Women's Health; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3466912/
Salehpour, A. et al; A 12-week double-blind randomized clinical trial of vitamin D; Nutrition Journal; https://www.ncbi.nlm.nih.gov/pubmed/22998754
Antoniak, E. et al; The effect of combined resistance exercise training and vitamin D; BMJ Open; https://www.ncbi.nlm.nih.gov/pubmed/28729308
Wang, T. et al; Vitamin D deficiency and risk of cardiovascular disease; Circulation Journal; https://www.ncbi.nlm.nih.gov/pubmed/18180395
Pannu, P. et al; Reductions in body weight and percent fat mass vitamin D obese subjects; Journal of Nutrition Research; https://www.ncbi.nlm.nih.gov/pubmed/26923506
Mallard, S. et al; Vitamin D Status and Weight Loss; American Journal of Clinical Nutrition; https://www.ncbi.nlm.nih.gov/pubmed/27604772