Blog Weight Loss Vitamin B12 Weight Loss: Proven Fact Or Just Another Popular Fad?

Vitamin B12 Weight Loss: Proven Fact Or Just Another Popular Fad?

b12 vitamins

A simple – and slightly unsettling – fact about weight loss is that most people will try just about anything to make sure that they shed those extra stubborn pounds. Be it a new diet, workout plan, or a new age procedure, as long as some celebrity or other influential person said that it worked for them, many will jump on the hype train without thinking twice about it or researching more on the matter.


A couple of years back, Vitamin B12 weight loss shots had been all the rage with American celebrities who all claimed that they used them to get fit. While the praise for these B12 weight loss shots and therapy seems to have disappeared from pop culture media, some people still believe in their power and efficiency.

But do B12 and weight loss have a correlating relationship? In this article, we are going to look further into this topic as we try to understand how B12 vitamin benefits weight loss, its side effects, and, above all, if this is another fad that you should not spend your hard-earned cash on.

What Is Vitamin B12?

Before diving into how B12 benefits weight loss or how much of it you should take to get your desired results, we must first understand what this nutrient is and where it comes from. According to the Harvard School of Public Health, Vitamin B12, also known as cobalamin, is an essential water-soluble nutrient naturally found in animal foods. These animal sources of vitamin B12 include meat, poultry, fish, eggs, milk, and dairy products. Clams and beef liver are said to have the highest concentration of this nutrient.

An important fact to note is that this nutrient is not usuallyfound in plants, hence, the people who consume a plant-based diet, such as vegans and vegetarians, are often advised to find alternative sources of vitamin B12 like supplements to remain in the best health. These alternative sources include supplements and fortified foods, such as enriched plant-based milk (like soy and rice milk), nutritional yeast, and breakfast cereals (9).

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b12 weight loss

How Does B-12 Help Your Body?

Our bodies use this water-soluble nutrient every day, so we all need to have a certain amount of it in our system at all times to avoid a deficiency. For teens (from 14 years) and adults, the recommended daily amount is 2.4 micrograms, while pregnant and breastfeeding women (or teens) require 2.6 and 2.8 micrograms, respectively (9).

The functions of this nutrient in the body include:

  • It is vital in the formation of red blood cells and DNA.
  • It maintains the central nervous system and is a key player in the function and development of brain and nerve cells.
  • It is crucial to protein metabolism. The process of breaking down the proteins consumed into molecules that can be absorbed by the small intestines.
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Please note that while Vitamin B12 deficiency is not common, probably because our livers can store this nutrient for anywhere between two to four years without being replenished (13), it is not unheard of.

According to WebMD, an inadequacy of this nutrient could be due to the following reasons:

  1. Atrophic Gastritis. It destroys the parietal cells leading to the reduction of the intrinsic factor, which is essential for the absorption of vitamin B12.
  2. Pernicious Anemia. Caused by a weakened lining of the stomach, a congenital condition or an autoimmune disease which causes your immune system to attack the cells in your stomach that produce the intrinsic factor, making it harder for your body to absorb this vitamin, leading to an inadequate number of healthy red blood cells.
  3. Any condition affecting the small intestine like Crohn’s disease or celiac disease.
  4. Immune system disorders, such as Graves’ disease or lupus.
  5. Diet, especially the vegan diet since it avoids all animal products which are the source of cobalamin.
  6. Certain medications (7)

Anyone with a deficiency of this nutrient is likely to suffer from megaloblastic anemia, in which your bone marrow produces large abnormally shaped red blood cells that do not function properly, and potentially neurological disorders like dementia, paranoia, depression, and behavioral changes (11).


Vitamin B12 Weight Loss: How Does It Work?

Vitamin B12 weight loss is something that some weight loss clinics advocate for claiming that a shot of this vitamin will be beneficial in helping you lose a couple of pounds. According to Medical News Today, the nutrient shots contain a synthetic version of vitamin B12 (known as cyanocobalamin) and are injected right into your muscle – not the vein.

So what does vitamin B12 do for weight loss? Proponents of B12 weight loss claim that the supplementation of this nutrient will give you energy and boost your metabolism, which in turn helps you burn fat and be rid of those extra stubborn pounds.

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Vitamin B12 And Weight Loss: What Does Science Say About It?

Is there any scientific proof that the B12 vitamin benefits weight loss? The facts are varied. On one hand, some research states that in some ways an extra boost of this nutrient can help you lose some pounds, while on the other hand, some studies say that it does not work.

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Let’s start with some positives on how B12 weight loss could work.

b12 weight loss

Significant Boost In Energy

This nutrient is often touted for its energy-giving benefits and with good reason. All B vitamins,  while they may not produce any energy by themselves, have been shown to play an important role in your body’s energy metabolism (16).

Vitamin B12, specifically, is known to be essential for cellular energy production (12). If you are not aware, cell energy is used to convert the foods, drink, and even air in the body to fuel and be used to propel us in our day-to-day activities.

For people with a vitamin B12 deficiency, research has shown that supplementing or just getting extra vitamins from food will boost their energy levels (1). Having more energy helps you move around more or even get up and work out, which all leads to burning extra calories throughout the day.

Increase In Metabolism

Metabolism is the chemical process the body uses to break down food and nutrients for energy, basically, it’s the rate at which your body expends energy or burns calories. A faster metabolism burns calories more quickly than a slower one, making it less likely that a person will put on or maintain their weight.

Common ways to boost your metabolism include eating more protein, sleeping more, working out, or consuming potentially metabolism boosting foods, such as eggs, caffeine, legumes and lentils, chili, flaxseeds, and even water. Nutrients have also been suggested to help increase your metabolism, helping in fat and weight loss.

A recent review in the Nutrients journal stated that there is an association between low vitamin B12 status and obesity, metabolic syndrome, type 2 diabetes, and hypertension.  (5). Animal studies have also shown that cobalamin has a significant role in metabolism and fat accumulation.

  • In 2016, the Frontiers in Nutrition journal published a study that showed severe cobalamin deficiency resulting in a significant increase in body fat percentage, induced adiposity (too much fat accumulation), and altered lipid profile in pregnant lab mice (8).
  • In 2018 researchers found that feeding B vitamins to rats not only led to slower weight gain – the rats were on a high-fat diet – but these vitamins also led to an increase in several enzymes that influence and boost metabolism (3).
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This makes sense because we know that Vitamin B12 is essential for the metabolism of proteins and fats (10). Yet although vitamin B12 is involved in metabolism, there is no evidence that increasing vitamin B12 intake or taking supplements can speed up your metabolism overall. It is only one part of a complex system.

Read More: What Is The Best Nut For Weight Loss: Lose Belly Fat And Those Extra Pounds

b12 weight loss

Lower Risk Of Obesity

For several years now, obesity has been regarded as a global pandemic, and everyday steps are being taken to not only help reduce the number of obese people in the world but also advise people on how they can avoid it or drop their weight to a healthy level.

If you are concerned about this issue then getting some B12 shots or supplements could be beneficial to you if you have a vitamin B12 deficiency:

  • In 2013, one study with 976 participants found an association between vitamin B12 deficiency and overweight or obesity. Participants who were overweight or obese tended to have lower vitamin B12 levels than those who were within a healthy weight range  (2).
  • In 2019, a study published by Frontiers in Endocrinology involving over 9000 participants found that people with lower serum vitamin B12 concentrations in their bodies were more likely to be obese as compared to those with higher concentrations (4).

Children too are not exempt from this risk. A study published in 2017 found that of the 256 volunteers, the 153 overweight children had significantly lower mean vitamin B12 levels than the other 103 children with healthy weights (6).

When Does Vitamin B12 Weight Loss Not Work?

Probably always. As seen in the points above, as a nutrient cobalamin will not necessarily lead to weight loss directly, but can work to benefit you in other aspects that could potentially help with the weight loss process.

For example, a boost in energy can help you work out more or channel your energy towards doing more at work. The first option is beneficial for weight loss, while the second option is good for productivity.

Concerning metabolism, as stated, a faster metabolic rate helps you burn calories quicker, preventing the accumulation of fat in your body. However, a faster metabolism is not enough to get overweight or obese people down to a healthy weight. Such a person will need to work out more and improve their diet to see any changes. And although vitamin B12 is involved in metabolism, that doesn’t mean that getting more of it will increase your metabolism. Metabolism is a complex set of processes with many factors involved. 

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In terms of obesity, the studies above only show us that those who are of a higher weight tend to have lower levels of this nutrient. They do not, however, state that increasing the amount of B12 in the body will help reverse this process.

A final point to note is that supplementing or increasing intake of vitamin B12 is only likely to benefit those with a deficiency. As of date, there is no scientific proof that shows any benefits in people who already have sufficient/normal cobalamin levels in their bodies.

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How Much B12 For Weight Loss?

If you are wondering how much B12 to take for weight loss, we would say that no amount you take will necessarily lead to weight or even fat loss. However, if you suspect that you might have a deficiency, eating more foods high in this nutrient or finding the right supplements might help you get rid of deficiency symptoms. You’ll need to talk to your doctor, who will test you for vitamin B12 deficiency and work with you to determine the cause and appropriate treatment. Because of the somewhat complex process by which vitamin B12 is absorbed, sometimes inadequate intake isn’t the cause of the deficiency, in which case eating more vitamin B12 foods or taking oral supplements wouldn’t solve the problem.

As mentioned above, the daily recommended amount for teens above 14 years old and adults is 2.4 micrograms, pregnant and lactating people need more, and the amounts required for children differ by age group.

How Much B6 And B12 For Weight Loss Results?

Like B12, B6 (aka pyridoxine) is a water-soluble vitamin that cannot be produced by the body and must be ingested from foods or supplements. In the body, pyridoxine also helps with the creation of red blood cells and neurotransmitters, as well as the metabolism of proteins, fats, and carbohydrates.

Some of its benefits include improving cognitive function in the elderly, lowering the risk of certain cancers, reducing PMS symptoms, including moodiness, irritability, forgetfulness, bloating, and anxiety as well as treating and preventing nausea and vomiting in pregnant women (14).

However, just as with B12, the research on how much B6 one should be taking to help with weight loss is lacking, and any benefit would likely only be to those who are deficient in vitamin B6. However, one 2006 study concluded that improving plasma levels of B6 through dietary intake may help maintain fat-free mass during periods of weight loss in overweight/obese women (15).

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The Bottom Line: Vitamin B12 Benefits Weight Loss – Fact Or Fad?

From all the facts shown above, we would say that B12 weight loss is a fad and not a proven scientific fact. This nutrient is not a miracle worker, and investing in injections or supplements will not magically make you lose several pounds. However, in people suffering from a deficiency, it is advisable to talk to your doctor about b12 supplements or injections – or even eating foods rich in nutrients – not for weight loss but for a better nutritional status and quality of life.



This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. A licensed physician should be consulted for the diagnosis and treatment of any medical condition. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!


  1. Association of vitamin B12 deficiency with fatigue and depression after lacunar stroke (2012,
  2. Association of vitamin B12 with obesity, overweight, insulin resistance and metabolic syndrome, and body fat composition; primary care-based study (2013,
  3. B Vitamins Can Reduce Body Weight Gain by Increasing Metabolism-related Enzyme Activities in Rats Fed on a High-Fat Diet (2018,
  4. Inverse Association Between Serum Vitamin B12 Concentration and Obesity Among Adults in the United States (2019,
  5. Low Vitamin B12 and Lipid Metabolism: Evidence from Pre-Clinical and Clinical Studies (2020,
  6. Negative correlation among vitamin B12 levels, obesity severity and metabolic syndrome in obese children: A case control study (2017,
  7. Proton Pump Inhibitors, H2-Receptor Antagonists, Metformin, and Vitamin B-12 Deficiency: Clinical Implications (2018,
  8. Severe but Not Moderate Vitamin B12 Deficiency Impairs Lipid Profile, Induces Adiposity, and Leads to Adverse Gestational Outcome in Female C57BL/6 Mice (2016,
  9. Vitamin B12 (2021,
  10. Vitamin B12 (2021,
  11. Vitamin B12 deficiency neuropathy; a rare diagnosis in young adults: a case report (2017,
  12. Vitamin B12 in Health and Disease (2010,
  13. Vitamin B12 or folate deficiency anaemia (2014,
  14. Vitamin B6 (2021,
  15. Vitamin B6 status improves in overweight/obese women following a hypocaloric diet rich in breakfast cereals, and may help in maintaining fat-free mass (2008,
  16. Vitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review of the Biochemical and Clinical Evidence (2020,
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