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Vitamin B12 and weight loss

Can vitamin B12 help you lose weight?

Vitamin B12 shots and supplements are popular for fighting fatigue and boosting energy levels. This article examines the evidence to determine if vitamin B12 aids weight loss.

Weight Management
This article is based on scientific evidence, written by experts, and fact-checked by experts.
We look at both sides of the argument and strive to be objective, unbiased, and honest.
Can vitamin B12 help you lose weight?
Last updated on January 13, 2024, and last reviewed by an expert on August 21, 2023.

People often take Vitamin B12 shots or pills, hoping for a weight loss boost.

Can vitamin B12 help you lose weight?

Some believe that more vitamin B12 can help reduce tiredness, give you more energy, and accelerate your metabolism.

Yet, studies on whether vitamin B12 really helps with weight loss show different outcomes.

This article will deeply explore if vitamin B12 truly aids in losing weight.

In this article

What is vitamin B12?

Also sometimes referred to as cobalamin, vitamin B12 is a water-soluble vitamin essential for several health aspects.

What every vegan should know about vitamin B12.
Suggested read: What every vegan should know about vitamin B12.

This vitamin is involved in forming DNA and red blood cells and is necessary for brain function, heart health, energy production, and more.

It’s found naturally in many animal products and sometimes added to fortified foods.

Vegans, vegetarians, older adults, and people with digestive issues that can interfere with nutrient absorption may be at a higher risk of vitamin B12 deficiency and need to supplement.

Summary: Vitamin B12 is a water-soluble vitamin involved in several aspects of health, including DNA synthesis, red blood cell formation, and brain function.

Vitamin B12’s effects on body fat and metabolism

Although human research is still minimal, some studies suggest that vitamin B12 could affect body fat and metabolism.

One review concluded that vitamin B12 plays a crucial role in fat metabolism, noting that a deficiency could be linked to increased fat accumulation and obesity.

Another animal study found that severe vitamin B12 deficiency significantly increased body fat percentage and cholesterol levels in pregnant mice.

One animal study showed that administering B vitamins to rats fed a high-fat diet reduced weight gain and increased levels of several enzymes that influence metabolism, compared with a control group.

However, current evidence is lacking, and additional high-quality studies are needed to determine how vitamin B12 may affect metabolism and body fat in humans.

Summary: Some animal studies suggest that a deficiency in vitamin B12 may increase body fat percentage and alter metabolism. More research in humans is needed.

Low levels of vitamin B12 may be linked to obesity

Interestingly, several studies have found that having adequate vitamin B12 levels may be associated with a lower risk of weight gain and obesity.

According to one large study of 9,075 people, having higher blood levels of vitamin B12 was associated with a lower risk of obesity.

Similarly, another study of 976 people showed that having low levels of vitamin B12 was linked to a higher risk of being overweight or obese.

What’s more, a study of 256 children showed that children with lower levels of vitamin B12 tended to have a higher body mass index (BMI), which is a measure of body size determined by height and weight.

Suggested read: A healthy BMI for women: Chart, calculator & factors

However, remember that while these studies show an association between vitamin B12 status and body weight, they don’t consider other potentially contributing factors.

Therefore, it can’t be concluded that vitamin B12 causes weight loss. More research is needed to determine whether vitamin B12 directly affects body weight or BMI.

Summary: Some studies show that lower levels of vitamin B12 may be associated with a higher risk of overweight or obesity. Further studies are needed to determine whether other factors may also be involved.

Signs of vitamin B12 deficiency

A vitamin B12 deficiency can lead to megaloblastic anemia, a condition characterized by a low number of red blood cells that are larger than usual.

9 signs and symptoms of vitamin B12 deficiency
Suggested read: 9 signs and symptoms of vitamin B12 deficiency

Megaloblastic anemia can cause a variety of symptoms and side effects, including:

Being low in vitamin B12 doesn’t always lead to megaloblastic anemia, and many people may only experience mild symptoms like fatigue.

Furthermore, while a deficiency in vitamin B12 may not cause weight gain, it can decrease energy levels and contribute to fatigue, making it harder to stay active and manage your weight.

Conversely, some studies show that a deficiency in vitamin B12 may cause appetite loss, potentially leading to weight loss if left untreated.

If you’re deficient in B12, your healthcare provider will likely recommend oral vitamin B12 supplements or injections to increase your blood levels.

Summary: Low levels of vitamin B12 can cause megaloblastic anemia, which is characterized by shortness of breath, headaches, and fatigue. Increasing your vitamin B12 intake can protect against deficiency to prevent these side effects.

Sources of vitamin B12

Vitamin B12 is found naturally in various food sources, including animal products like meat, fish, poultry, eggs, milk, and milk products.

12 foods that are high in vitamin B12
Suggested read: 12 foods that are high in vitamin B12

It’s also added to many fortified foods, such as breakfast cereals and plant-based milk like almond, soy, or hemp milk.

Vitamin B12 supplements are also available in several forms, including tablets, capsules, liquids, and lozenges.

It’s often found in many multivitamin supplements as well.

Those who don’t regularly consume animal products rich in vitamin B12 may want to consider adding fortified foods to their diet or taking a supplement to meet their nutritional needs.

Summary: Vitamin B12 is found in animal products and fortified foods. It’s also available in supplement form to help you meet your needs.


Vitamin B12 is a crucial vitamin that helps your brain, heart, and the making of red blood cells and DNA.

Some studies suggest that the right amount of vitamin B12 in your blood might lower the chance of being overweight. Animal tests also hint that it might influence fat and how our body uses energy.

Eating more vitamin B12 can prevent low levels, which can help you feel less tired.

Yet, if you’re already getting enough of this vitamin and aren’t lacking any nutrients, we don’t know if having more of it will help with weight loss.

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