If you’re living with obesity, you’ve probably come across a range of products and supplements that promise to help with weight loss. Vitamin B12 shots and pills are among them. But does B12 actually help you lose weight? The short answer is no. There’s no evidence that B12 injections or supplements lead to weight loss.

Vitamin B12 is an essential nutrient that helps your body function normally. If your B12 levels are already in a healthy range, taking supplements probably won’t affect how you feel or how much you weigh. In this article, learn more about the role of B12 and the source of the weight-loss myth.

What Is the Role of Vitamin B12?

Getting enough vitamin B12 through food or supplements helps you stay healthy and avoid problems like fatigue and depression, which can be caused by low B12 levels. This nutrient plays a few key roles in keeping your body healthy. Vitamin B12:

• Creates red blood cells — Low B12 levels can lead to fewer or poorly formed red blood cells, which may result in a type of anemia.
• Supports nerve health — Without enough B12, your nerves may not function properly. This can lead to symptoms like numbness, tingling, muscle weakness, or confusion.
• Helps your metabolism — Vitamin B12 helps your body convert nutrients into energy. A deficiency can make this process less efficient, leaving you feeling tired or sluggish.

In the United States, having very low B12 levels isn’t very common because this nutrient is easy to get in a normal, balanced diet. Meat, fish, eggs, dairy, and plant-based milks and products all supply vitamin B12.

How Are Vitamin B12 and Body Weight Linked?

The idea that vitamin B12 injections can help you lose weight may have come from studies showing a relationship between obesity and low B12 levels. Some scientific evidence suggests that B12 deficiency is more common among adults with obesity than among those without obesity. “Obese” is a medical term for having a body mass index (BMI) score of at least 30. However, the BMI score is a measure of height and weight that does not always equate with health.

A study of people ages 5 to 25 found a link between low B12 levels and body weight. Participants with higher vitamin B12 levels were more likely to have a BMI in the normal or underweight range. In contrast, those with obesity or severe obesity tended to have lower levels.

Low B12 Levels and Obesity

There are a few reasons why low B12 levels might be linked to obesity. First, vitamin B12 plays a role in how the body breaks down fats. When levels are low, fat metabolism may be less efficient. Second, B12 helps with key metabolic processes that turn food into energy. Without enough B12, metabolism can slow down, making it hard for the body to use energy efficiently.

If someone has low vitamin B12 levels and is experiencing symptoms like fatigue and depression, restoring their B12 levels may help them feel more energetic. The increased energy might make it easier to be active, which can support weight loss — but that doesn’t mean that B12 itself causes weight loss.

There’s no evidence that B12 injections or supplements boost metabolism or burn fat in healthy people with normal B12 levels. Getting enough vitamin B12 is important for overall wellness, but unless you’re deficient, taking extra B12 supplements won’t affect your weight.

Who Might Need Vitamin B12 Supplements?

Just because B12 injections won’t cause weight loss doesn’t mean B12 supplements are harmful. B12 supplements can be helpful, especially for people at risk of deficiency. If you fall into one of these groups, supplements may help improve your energy levels or support overall health. People most likely to benefit from B12 supplements include:

• Older adults — As you age, your ability to absorb B12 may decline. The risk of deficiency rises after 75.
• People with digestive diseases — Conditions like Crohn’s disease or ulcerative colitis can make it harder for the body to absorb certain nutrients, including vitamin B12. If you live with a digestive condition, your doctor may recommend checking your B12 levels regularly.
• Vegans and vegetarians — Vitamin B12 isn’t naturally found in most plant-based foods, so people who avoid animal products are more likely to have low levels. The good news is that many plant-based foods are now fortified with vitamin B12.
• People taking certain medications — Some drugs can cause low B12 levels as a side effect, including heartburn medications, birth control pills, and metformin (commonly used to manage diabetes and sometimes to support weight loss).

Could Vitamin B12 Be Part of an Obesity Treatment Plan?

Vitamin B12 supplements likely won’t play a role in your obesity treatment plan, unless you’ve been diagnosed with a deficiency. If your B12 levels are normal, your healthcare provider probably won’t recommend B12 supplements.

Effective obesity treatment plans often include a combination of strategies, such as:

• Making dietary changes
• Getting more physical activity
• Working with a mental health professional
• Taking prescription weight-loss medication
• Considering weight-loss surgery, if appropriate

It’s wise to be suspicious of any product or supplement that promises a quick fix or easy weight loss. Talk with your healthcare provider to establish a treatment plan that’s realistic, personalized, and safe for you.

Talk to Your Healthcare Team

If you’re trying to lose weight or experiencing unusual weight gain or fatigue, it’s a good idea to talk with your doctor. They can check your vitamin and mineral levels and recommend the right treatment for you.

Whatever your goals, remember that you are not alone. Working with a care team and speaking with people who understand life with obesity can help you find a treatment plan that works to improve your health.

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On MyObesityTeam, people share their experiences with obesity, get advice, and find support from others who understand.

What obesity treatments have helped you improve your energy levels? Let others know in the comments below.