Exploring the link between vitamin D and weight loss

Key takeaways

• Vitamin D plays a role in metabolism and weight regulation by supporting muscle growth, reducing fat storage, and improving insulin sensitivity.
• Low vitamin D levels are linked to weight gain and metabolic issues, including insulin resistance and a higher risk of obesity.
• While vitamin D supplementation may support weight loss, it’s not a magic solution, and maintaining adequate levels through sun exposure, diet, or supplements is key for overall health.

We all know that micronutrients, vitamins and minerals are an important part of our health and well-being — but did you know they can also impact your weight?

There are several vitamins that can impact our metabolism, body fat and weight, one of which is vitamin D.

You might know it as the 'sunshine vitamin', and while the nickname sounds fun, it actually plays a serious role in your health.

In this article we will explore what vitamin D is, how it impacts your metabolism, links between vitamin D deficiency and weight gain, how it can support weight loss, and how to increase your vitamin D levels.

What is vitamin D?

Vitamin D is a fat-soluble vitamin that can be produced in the body, found in certain foods, and taken as part of a supplement regimen [1].

It is stored in fat tissue, and in order for the vitamin to work effectively, it is turned into a hormone by the liver and kidneys.

Once it is activated, vitamin D helps calcium absorption and levels in the body, which is essential for muscle and bone health. Vitamin D is also important for your immune system, skin, brain, and overall health.

To produce vitamin D, the body requires ultraviolet (UV) radiation, which we get through sun exposure. This is why vitamin D is sometimes called the 'sunshine vitamin'.

Our vitamin D levels naturally change with the seasons, and the amount of sun exposure you need to produce vitamin D can vary depending on your skin type, UV levels, the time of year, and your existing vitamin D levels [2].

However, it's important to remember that too much sun exposure can cause sunburn, skin cancer, and damage to our eyes.

Small amounts of vitamin D are found in a few foods, such as fatty fish and eggs, and some types of fortified products such as spreads and cereals [3].

If you don't regularly meet your recommended vitamin D intake through food and sun exposure, you might want to consider vitamin D supplementation to avoid developing a deficiency.

How does vitamin D impact your metabolism?

There are several links between vitamin D levels and metabolism.

For one thing, as we mentioned at the beginning of the article, vitamin D helps your body to develop and maintain muscles.

Having more lean muscle mass can increase your metabolism and basal metabolic rate because lean muscle requires energy from your body to maintain [4].

Vitamin D can also reduce the creation of new fat cells and fat storage, and increase the production of serotonin and testosterone, which boost your metabolism and therefore aid weight loss.

Additionally, calcium homeostasis (which is supported by vitamin D) plays a role in metabolic health.

Healthy vitamin D levels can also improve insulin sensitivity, while low vitamin D levels have been associated with insulin resistance [5].

Insulin resistance prevents your body from effectively using glucose for energy and causes metabolic dysfunction. It is also associated with conditions including polycystic ovary syndrome, obesity, and diabetes.

The link between vitamin D deficiency and weight gain

If you don't have adequate vitamin D levels, you might be more prone to weight gain and metabolic syndrome.

Metabolic syndrome (also called insulin resistance syndrome) is a group of conditions or risk factors that increase your chances of heart disease, stroke, high blood pressure, and other serious medical issues [6].

Obese and overweight people, or people with a high body mass index (BMI), also appear to have a higher likelihood of low vitamin D status [7].

Research has found obese subjects are 35% more likely to have low levels than non-obese people, and 24% more likely than overweight people.

However, the exact link or cause is not clear [8].

Some have hypothesised that this could be due to overweight and obese subjects eating fewer vitamin D-rich foods, while others believe it is due to the fact that the fat-soluble vitamin gets stored in their fat cells and doesn't circulate properly, and others believe it could be due to other health issues or lifestyle factors.

Other potential factors in vitamin D deficiency and weight gain could be symptoms including fatigue and muscle weakness [9] — if you are experiencing these side effects, you might struggle to exercise regularly, which could contribute to weight gain.

Clearly, more research needs to be done to investigate the link between vitamin D deficiency and overweight people.

It's not just about weight though — low vitamin D levels are also associated with poor bone health, osteoporosis, falls, fractures, autoimmune disorders, and chronic diseases [10].

How vitamin D can support weight loss

As we have covered, there are a few ways that vitamin D supports your metabolism. But are there other links between vitamin D and weight loss?

One clinical trial study examined vitamin D weight loss among overweight postmenopausal women [11].

Half the women were given vitamin D supplementation, and they were all given a reduced-calorie diet and an exercise routine.

Over 12 months, the women using vitamin D supplementation experienced more weight loss than those who did not use the supplement — but the difference was only a few kilograms.

A 12-week trial looked at vitamin D supplementation in overweight and obese women, with half given a supplement and half given a placebo [12].

Those who were given vitamin D supplements had higher Serum 25(OH)D (serum vitamin D) and their body fat decreased significantly, but they did not have significant differences in their waist circumference or body weight.

Another small study done on overweight and obese women over 6 weeks found body mass index, body weight, and waist circumference all decreased among those taking vitamin D supplements [13].

So from these studies, it appears vitamin D status can play a part in weight loss or fat loss for overweight or obese women, but it is definitely not the key.

If you are trying to lose weight or body fat and need a little help to reach your goals, a programme like the Juniper Weight Reset could provide the support you need.

Unlike some other weight loss programmes, it is not simply a quick fix but will set you up to see real results and develop healthy habits that stick.

The holistic programme combines clinically proven medication (Wegovy or Mounjaro) with ongoing professional advice from clinicians and health coaches and access to a supportive online community.

Through these key elements combined, the programme will equip you with the tools you need to lose weight and reduce body fat, develop a healthy exercise routine, and reset your metabolism. Most importantly, it will put you on the path to making long-term lifestyle changes.

Can you get too much vitamin D?

According to the NHS, adults and children over the age of 1 need 10 micrograms (or 400 international units) of vitamin D per day [3].

While vitamin D is very important for your health, it's also important to be aware that you can definitely overdo it, and excessive vitamin D intake can also have dangerous results.

It can lead to nausea, vomiting, muscle weakness, loss of appetite, and an increased risk of kidney stones [14]. In some extreme cases, it can even be toxic.

Experts believe excessive vitamin D intake does not occur naturally from sun exposure but can happen if you use tanning beds.

Typically, dangerously high intake comes from consuming foods or supplements that contain excessive amounts of vitamin D (often through manufacturing error) or unintentionally overusing vitamin D supplements.

How to increase your vitamin D levels

Low vitamin D levels are extremely common and are believed to impact roughly half the population, but that doesn't mean it's not serious [15].

Older adults, breastfeeding infants, people with limited sun exposure, people with naturally dark skin, people with conditions that limit fat absorption or vitamin D absorption, and obese and overweight people have a higher risk of vitamin D deficiency [16].

People who are experiencing a vitamin D deficiency don't always have symptoms, but some experience muscle pain and weakness, fatigue, or bone pain [17].

And as we have covered, low vitamin D can also play a role in weight gain, which can put you at an increased risk of other health conditions.

If you suspect you might have a vitamin D deficiency, you can speak with your doctor and get your levels checked through a blood test.

As we mentioned at the beginning of the article, there are several sources of vitamin D and it can be ingested in food, produced by your body after sun exposure, or taken in supplement form.

Ideally, you'll want to get it naturally through spending time outside and dietary intake, but if this is not possible, your doctor can recommend the best vitamin D supplements and the right amount to suit your needs.

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