Vitamin B12 for Weight Loss

The chemical known as cyanocobalamin, or vitamin B12, is an important nutrient for cell metabolism and sometimes used as an enegy booster in supplement form. It is also often marketed as a weight loss aid, and is used as such in many weight loss clinics. However, is it useful as such? Do people actually lose weight taking vitamin B12? In this article we'll take a look at the evidence, both scientific and anecdotal, and see if we can answer that question.

In weight loss clinics around the world, B12 supplementation in the form of injection is popular as a way to lose weight. As an example, see the Weston MedSurg Center in Charlotte, North Carolina, where they offer a complete dieting plan. Included are monthly B12 injections. But most experts disagree with this.

For instance, the world-famous Mayo Clinic emphatically says "no" to B12's effectiveness. They quote a 2005 study that showed patients who took a B12 supplement gained weight a little more slowly than those who didn't, but they also cautioned that this was only one study. The number of studies directly researching any connection between B12 and weight loss rather thin, so there does not appear to be any scientific conclusion on this. Well, how about anecdotal stories, then?

On the popular discussion forum on, one person had to get B12 shots for another condition. She received the shots once every three weeks, but noticed something interesting on those weeks. While she kept her diet and exercise the same, every three weeks she would lose three times as much weight as she normally did. Interesting that there was a definite difference every three weeks. This does seem to point to B12 as the "culprit." But let's look at another one.

Another person had been trying to lose weight for a long time. She said she had tried everything possible, and was about to get gastric bypass surgery but decided to try one last thing. She began taking B12 supplements, and the first week of doing so she lost a pound. But she continued to do it, and her weight loss slowly increased until she lost a total of 110 pounds.

Now, as anecdotes, these are by definition not reliable evidence. That doesn't mean they are necessarily false; it just means there may be other factors unaccounted for.

So, unfortunately, the evidence is not quite clear. While completely lacking in scientific support, Vitamin B12 as weight loss supplement may or may not work. The fact that so many people swear by it may mean there is something to it, but weight loss supplements are very difficult to judge as there is such a large number of factors going on. The slightest change in diet or exercise or even an unknown may be responsible for a perceived benefit from B12. However, we do suggest you give it a try yourself to see how it works for you.