Does biotin cause weight gain?

Despite some claims of people gaining weight while taking biotin supplements, there is not sufficient evidence connecting biotin intake to weight gain.

Outside of anecdotal claims, it's difficult to find any evidence that biotin causes weight gain on its own, and there simply aren’t many studies that investigate a connection between biotin and weight gain. While there may be a wide range of theories linking biotin supplementation to weight gain, research is very limited.

One theory that sometimes emerges is that some people who take biotin supplements believe that doing so allows them to eat more without gaining weight. Biotin helps the body convert the carbohydrates, fats and proteins you eat into energy. Some people believe that increasing their intake of B vitamins such as biotin can help them boost their metabolism. As a result, they may consume more calories than recommended, leading to weight gain.

It's unlikely that most healthy people would have a medical need for extra biotin. There's no recommended dietary allowance (RDA) since there's not enough evidence to suggest that a daily intake is required in certain amounts. However, there is an adequate intake (AI) level, which is the amount assumed to ensure nutritional adequacy. For most men and women older than 19, the level is 30 micrograms. It's very rare to have a biotin deficiency, as the vitamin is found in a variety of dietary sources, such as beef liver, cooked eggs, salmon, avocados, pork, sweet potatoes, nuts and seeds.

On the other hand, increasing the amount of biotin in your diet likely wouldn't be harmful. No side effects have been found for those who have taken up to 10 milligrams of biotin supplements daily. It is important to note, however, that too much biotin can interfere with some laboratory tests, including thyroid level tests.

When it comes to health goals like losing or gaining weight, there is no clear evidence for or against using biotin for these purposes. Research linking biotin to weight gain or weight loss is lacking.  If you are concerned that you are not getting enough biotin, or are considering biotin supplements, talk to your healthcare provider so they can assess your diet and help you determine if a supplement is right for you and your health goals.

Updated by Amy Magill, MA, RDN, October 2024.