Saturday, July 4, 2015

Fat Loss Increases Vitamin D, But Taking More "D" Won't Trigger Fat Loss - Did We Fall for a Stupid Logical Fallacy?

Working out in the sun will make you lose fat, taking D3 supplements will not.
Have you been wondering why you didn't lean out magically in the past year even though you're taking a ton of vitamin D? Well, maybe it's because your previously low vitamin D levels were nothing but a symptom of your extra-pounds. One that will disappear with weight loss and one that may have mislead scientists and laymen alike to assume that vitamin D supplementation may help you lose weight.

In their latest study, scientists from the Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québe tried to get to the bottom of the relationships between changes in 25(OH)D levels and changes in adiposity volume (total and by adipose tissue compartment | Gangloff. 2015).
There are many ways to get your vitamin D learn more the SuppVersity

How Much To Take?

Leucine, Insulin & Vitamin D

Vit. D Speeds Up Recovery

Overlooked D-Sources

Vitamin D For Athletes!

Vitamin D Helps Store Fat
To do so, the researchers recruited sedentary, abdominally obese and dyslipidemic men (n=103) for a a 1-year lifestyle modification program targeted at weight loss.

Body weight, body composition, and fat distribution were assessed by dual-energy X-ray absorptiometry and computed tomography while 25(OH)D levels were measured with an automated assay. Well, the results of these assessments were interesting, to say the least.

Lowe your body fat, increase your vitamin D levels, it's as "simple as that"

Firstly, the 1-year intervention resulted in a 26% increase in circulating 25(OH)D (from 48±2 nmol/l or 19±0.8 ng/ml (±s.e.m.) to 58±2 nmol/l or 23±0.8 ng/ml, P<0.0001); and secondly, this happened alongside a 26% decrease in visceral adiposity volume (from 1947±458 cm3 to 1459±532 cm³).
Next bad news: You should know this already, but I am going to repeat it, because people keep ignoring the risk of taking tons of vitamin D like lemmings. If you consume too much D with tons of calcium you are at risk of calcification. What's less known, but only recently confirmed once again is that high vitamin D levels together with low dietary calcium intakes will increase bone resorption and decrease bone mineralization in order to maintain normal serum calcium levels (Bashir. 2015).
Subjects were individually counselled by a kinesiologist and a nutritionist once every 2 weeks during the first 4 months with subsequent monthly visits in order to elicit a -500 kcal daily energy deficit and to increase physical activity/exercise habits.
Figure 1: Changes in serum 25OHD (vitamin D) levels and visceral fat during the 1-year lifetime intervention (left); illustration of the logical fallacy that makes people assume that popping vitamin D triggers weight loss.
Secondly and more importantly, there was a significant inverse correlation between the changes in all adiposity indices, especially Δvisceral (r=−0.36, P<0.0005) and Δtotal abdominal (r=−0.37, P<0.0005) adipose tissue volumes with the significant increases of 25(OH)D the scientists observed, when they analyzed the blood of their subjects. Now, this could certainly mean that taking vitamin D supplements will reduce your body fat, but
  • well-controlled studies like Wamberg, et al. (2013), who found marginal, non-significant increases in subcutaneous fat and no change in visceral fat in response to 7,000 IU vitamin D/day in their controlled randomized trial with obese adults with low vitamin D levels, or 
  • meta-analyses like the most recent one by Pathak et al. which found that "[v]itamin D supplementation d[oes] not influence the standardized mean difference (SMD) for body weight, FM, %FM or LBM" (Pathak. 2014) 
make it hard to believe that the results of singular studies that were published in smaller open-access or pay-for-publishing journals like the one Salehpour et al. did in 2012 are more than outliers (note: different rules may apply if vitamin D is administered alongside other dietary or lifestyle interventions).

What remains unquestionable, though, is the correlation between high body fat levels and low vitamin D levels that is consistent over almost all observational (Wortsman. 2000; Arunabh. 2003; Kremer. 2009; Lagunova. 2009; Lenders. 2009; Forney. 2014) and experimental studies (Blum. 2008; Lee. 2009) in both sexes and across all age-groups. To interpret this as evidence in favor of potential body-fat reducing effects of vitamin D supplements is yet totally unwarranted.
Rather than a reduction in body fat, Nimitphong et al. (2012) observed an increase in body fat w/ vitamin D supplementation - albeit in a high fat diet scenario in rodents, which is why I wouldn't consider this "proof" of detrimental effects either.
Bottom line: You've read about (a) the fact that obese people need much more vitamin D to normalize their 25OHD levels on the SuppVersity, before and (b) you have likewise read about the fact that vitamin D acts as an acute phase reactant that may be "burned" in the fire of chronic inflammation (Waldron. 2013). Against that background Gangloff's most recent study provides just another piece in the puzzle that may eventually make the unproven "vitamin D for fat loss" myth tumble.

How's that? Well, if A, which is in this case obesity, causes a reduction of circulating vitamin D, either by increased uptake into the fat cells or as a side-effect of the obesity induced chronic inflammation, restoring B, which, in this case, is vitamin D, this will not necessary reverse A, i.e. the previous weight gain.

What do you say? Yes, part of the increase in vitamin D in the Gangloff study could in fact be triggered by an increase in potentially health(ier) vitamin D rich foods, but you don't really think that this is what triggered the weight loss... don't confuse correlation with causation, when there's evidence for a causal relationship only for vitamin D being (a) used up by chronic inflammation (Waldron. 2013) and (b) its well-known storage and thus "disappearance" from the blood into increasing body fat stores (Rosenstreich. 1971), but no convincing evidence for vitamin D's ability to trigger fat loss. Now, all this doesn't mean it's useless to normalize your 25OHD levels, but it does mean that vitamin D3 is not a fat loss wonder drug | Comment on Facebook!
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