Vitamin D & Weight: Does Deficiency Make You Fat?

No, a vitamin D deficiency does not make you fat. If anything, the arrow points the other way: people who carry more body fat tend to have a lower vitamin D blood level and need more vitamin D to reach the same value. That does not make vitamin D a slimming aid, and we promise nothing of the kind. What is worth doing: have your own blood level measured and set the amount by that number, not by the figure on the tub. Below you will find why this is so, how much more a larger body needs, whether daily or weekly is better and when in the day to take your tablet.

Bigger belly, lower blood level: which comes first?

A search for "vitamin D deficiency belly fat" sounds like a cause: too little vitamin D, therefore more belly. The best answer comes from genetics. Researchers compared gene variants that go with a higher body mass index against variants that bring a higher vitamin D level. The result: variants for a higher BMI went with a lower vitamin D level. Variants for a higher vitamin D level showed hardly any link to BMI. The authors see little evidence that the vitamin D level drives BMI. They do not rule out very small effects.

For you that means the deficiency is usually the consequence, not the trigger. No blame attached. It explains why a low value is so common with more body fat, and why a tablet alone will not make your trousers any looser.

Why a larger body needs more vitamin D

Vitamin D is fat-soluble. It is plausible, then, that it spreads across more body mass in a larger body, so the blood level ends up lower for the same amount. Exactly why is not settled. The effect itself shows up clearly in the data.

A large analysis of data from a preventive health programme with healthy adults sorted people by BMI. With overweight the blood level was lower on average, with marked overweight lower still. And the same extra amount raised the value more at normal weight than at overweight. To reach the same target value, people with overweight needed one and a half times the amount, and with marked overweight a multiple of what is enough at normal weight. The authors did not want to derive concrete doses from this, and neither do we. The message: there is no one standard amount for everyone.

What does that mean day to day? If the scales show more than you would like, less of the usual pack amount may reach you than reaches the slim colleague in the office who takes exactly the same tub from exactly the same shelf. Your blood level shows how much really arrives. Everything else is guessing.

Does vitamin D help you lose weight? Not even D2

There is no authorised claim for vitamin D on body weight, and we make none. Reviews of several trials in which vitamin D was given alongside a diet or weight-loss programme found no reliable difference in body weight. Small effects on BMI and waist circumference are being discussed, and the author of the review considers further research necessary. That is not enough for a promise.

The same goes for vitamin D2, which people often search for. D2 or D3: both are vitamin D, neither is a fat burner. We sell vitamin D3. And belly fat? It responds to food, sleep, exercise and stress. You will find more in the guide to visceral belly fat, linked below.

Tired, heavier, vitamin D under suspicion? Then get a blood test

Weight gain and tiredness have many causes: lack of sleep, stress, less exercise in winter, medication, hormonal changes, a thyroid that is not running smoothly, or simply that everyday life gets tighter after the summer and dinner lands on the table later than it used to. A low vitamin D level is one of several candidates. The easiest to check. You can only be sure through a blood test with your family doctor. What is measured is 25-OH-D. Ask right there whether the thyroid should be checked too.

A blood test also makes sense because afterwards you no longer wonder between "it helps" and "it does not". Your value is the starting number. After a few months you measure again and see whether your amount suits you.

Daily, weekly or every five days: the total amount is what counts

Whether vitamin D is better daily or once a week is something many people ask. An analysis of numerous trials, which compared taking it at longer intervals with taking it daily and took very different amounts and time spans into account, reached a clear result: similarly effective. At equal amounts daily ranked slightly ahead, but the difference was not reliable. In short, your body stores vitamin D. It counts in sums, not in days.

Our Vitamin D3 Depot + K2Pure® fits exactly that logic. One tablet contains 5,000 IU (125 µg) of vitamin D3 and 100 µg of vitamin K2. You take it every 5th day. On average that is 1,000 IU a day, without having to think about it daily. If you tend to forget a daily dose, the five-day rhythm copes equally well with shift work, home office and holidays, because you only mark one fixed morning in the calendar and do not think about it for the rest of the week. A tub of 180 tablets lasts 900 days on paper.

If your blood level says you need more, agree the adjustment with your doctor instead of improvising. That is also where it is clarified whether vitamin D is right for you at all.

The best time of day? It is the meal, not the clock

Morning, noon, evening: it does not matter. Fat on the plate, that counts. Vitamin D and vitamin K are fat-soluble. In one small observation the blood level rose by about half after people moved their usual amount from an empty stomach to the largest meal of the day. Mind you, a small group without a comparison group, but the rule costs you nothing.

In practice that means: the tablet with your breakfast bread and butter, with muesli and nuts, or with dinner and olive oil on the salad. Only a black coffee alongside? Then wait until there is something proper to eat.

If you take anticoagulants, clear the intake with your doctor first. Vitamin K contributes to normal blood clotting, and that is the reason.

How long until the level rises?

Absorbing and topping up are two different things. In the gut vitamin D is absorbed after the meal, but the blood level builds up over weeks to months. In the trials on taking it at longer intervals, observation mostly ran over several months. A blood test after three weeks therefore tells you little. Plan the check after a few months, in the same lab and ideally in the same season. More on this in the guide on how long vitamin D takes to work.

Your plan in four steps

• Get your blood level measured. 25-OH-D, ideally together with the thyroid value.
• Set the amount by the value. A larger body needs more; your practice agrees the number with you.
• Take it with a meal containing fat. For example our depot every 5th day with breakfast bread.
• Measure again after a few months. Numbers instead of gut feeling.

Alongside come the things that really count for weight: sleep, exercise, protein, vegetables. Vitamin D adds to them, it does not replace them.

Matching Products from Scheunengut

Our Vitamin D3 Depot + K2Pure® is the tablet for the five-day rhythm: 5,000 IU (125 µg) high-dose vitamin D3 and 100 µg vitamin K2 as K2Pure® (MK-7, over 99 % all-trans) in one tablet, one every 5th day. 180 tablets last 900 days. The tablet is vegan, independently lab-tested and made in Germany. Vitamin D contributes to the maintenance of normal bones, to the normal function of the immune system and to the maintenance of normal muscle function. Vitamin D also contributes to the normal absorption and utilisation of calcium and phosphorus. Vitamin K contributes to the maintenance of normal bones and to normal blood clotting. The high-dose depot is not suitable for pregnant or breastfeeding women, children and adolescents. Behind it stands Scheunengut: since 2012, no investors, with a focus on pure raw-material quality.

Frequently Asked Questions (FAQ)

Does a vitamin D deficiency make you fat?

No. Genetic data suggest a higher BMI lowers the vitamin D level, not the reverse. A low value is common with more body fat but mostly a consequence. A blood test at your doctor's settles it.

Can you lose weight with vitamin D, including vitamin D2?

No, vitamin D is not a slimming aid, neither as D3 nor as D2. There is no authorised claim on body weight, and reviews show no reliable difference in weight. Food, sleep and exercise remain the lever.

Does vitamin D help against belly fat?

There is no evidence for it, and we do not promise it. A low vitamin D level is more common with more belly fat, but according to the data more as a consequence. Belly fat responds to food, sleep, exercise and stress.

Do I need more vitamin D if I am overweight?

On average, yes. For the same amount the blood level is lower in a larger body. There is no fixed number for everyone. Have your 25-OH-D measured, set the amount by it and check again after a few months.

Is it better to take vitamin D daily or once a week?

Both work. An analysis of many trials found taking it at longer intervals similarly effective to daily. What counts is the total amount and that you stick with it. With our depot it is one tablet every 5th day.

What is the best time of day to take vitamin D?

The clock is secondary. Take it with a meal containing some fat, ideally the largest of the day, because vitamin D is fat-soluble. One small observation saw clearly higher blood levels than with intake on an empty stomach.

How long does the body need to absorb vitamin D?

Absorption in the gut happens with the meal. The blood level, however, builds up over weeks to months. So do not measure after three weeks but after a few months, ideally in the same lab.