Does a vitamin D deficiency make you fat?

On average, women with a vitamin D deficiency have more body fat, especially abdominal fat, and less muscle mass than women with sufficient vitamin D levels. This was the result of a Brazilian study. It isn’t the first indication of a link between vitamin D and obesity. This might sound great at first. If you’re struggling with a few extra kilos, you might be thinking there’s an easy way to shed the pounds now: just take some vitamin D. But, of course, it’s not that simple. Above all, the study itself has several limitations. First, only women of childbearing age were examined. Second, there was only a small number of study participants (124 women). But another aspect is much more important:

Correlation, not causation – what does that actually mean?

The study only shows a correlation, i.e. a statistical relationship, between the two factors of vitamin D and body fat. It simply compared whether the group of participants with vitamin D deficiency differed in terms of body fat (especially abdominal fat) from the group with sufficient vitamin D levels. This showed that vitamin D deficiency correlates with more abdominal fat. But wait, a causal relationship would mean a vitamin D deficiency directly leads to more abdominal fat or vice versa. But you can’t just assume this. The authors of the study also emphasise that further research is needed to understand the exact mechanisms and clarify possible causalities.

Can taking vitamin D make your belly fat disappear?

Science doesn’t yet have a clear answer to this question. Although there are indications (such as the study mentioned) of a correlation between vitamin D deficiency and increased abdominal fat, this doesn’t necessarily mean that an increased vitamin D intake leads to a reduction in abdominal fat. So far, there are no studies that can prove exactly this effect.

It’s important to note that the observed effects mainly occur in people with a vitamin D deficiency. This means that if you already have enough vitamin D in your body, it’s unlikely you’d benefit from taking extra.

However, it may well be worth having your own levels checked. In Central and Northern Europe, the little sunlight, particularly during long winters, means that a large proportion of the population has a vitamin D deficiency. Studies by the Robert Koch Institute suggest that more than half of the adult population in Germany suffers from a vitamin D deficiency. The proportion is considerably higher among older people. The Federal Office of Public Health (page in German) also estimates that around 50 per cent of the Swiss population is undersupplied with vitamin D.

The positive effects of vitamin D

There’s no two ways about it: vitamin D has been proven to have a number of positive effects on the body. It supports bone health, promotes calcium absorption and plays an important role in the function of your immune system. It’s also associated with improved mood and mental health. An improvement is noticeable if there was previously a deficiency. If your vitamin D level is already sufficient, additional benefits of supplementation are less clear.

Supplementation: consulting with a doctor is essential

Before you decide to take vitamin D as a dietary supplement, you should definitely discuss it with your doctor. As excess vitamin D isn’t excreted but stored in the body, high doses can lead to an overdose of the fat-soluble vitamin. Although this is rare, it can lead to health problems, including kidney stones, calcification of blood vessels and other tissues, nausea, vomiting and weakness. Supplementation is generally only advisable if a deficiency has actually been detected by a blood test.

Vitamin D definitely plays an important role in your health. Nevertheless, it isn’t a panacea and shouldn’t be taken as a dietary supplement without medical advice.

And if you really want to shed a few extra pounds, the tried and tested strategies are still the best: a healthy, balanced diet and regular exercise are highly recommended.