B12 Shots for Weight Loss

Admit it or not, the search for the most effective and safest weight loss solution is never-ending. One popular approach is B12 shots for weight loss. Vitamin B12 injections have been given for years in hopes of increasing energy and promoting weight loss. 

Even a few celebrities like Madonna, Justin Timberlake, Katy Perry, and Rihanna have reportedly tried B12 shots. It was then that the trend started, and somehow, B12 shots got linked with weight loss. But do B12 shots for weight loss really work? Are they approved for weight loss?

Now, you might be thinking this is such a cool idea. Why spend hours at the gym and stick to a strict diet when all you need is a B12 shot and all done? Hold on. This idea is far from true. 

Supplementing with vitamin B12 is extremely common in the US since its deficiency is widespread. In fact, many Americans regularly get vitamin B12 shots as these are believed to help with energy levels, increased metabolism, and weight loss, among others.

However, there's little to no evidence to support the claim that B12 injections help in weight loss. 

This article takes a detailed look at whether or not B12 shots for weight loss really work. It also explores the potential side effects and alternatives you can consider in your weight loss journey.

What are B12 shots, anyway?

Let's start understanding the basic context: Vitamin B12.

Understanding Vitamin B12

Vitamin B12, scientifically known as cobalamin, is an essential water-soluble vitamin that our body needs for many key functions. Two of its common forms are cyanocobalamin and hydroxocobalamin.

It is naturally found in a variety of animal-based food products and is sometimes added to fortified processed foods. As per the National Institute of Health, some of the foods include fish, meat, milk, eggs, etc. It is available as an oral supplement in tablet form and B12 shots. 

As 1 of the 8 B vitamins, Vitamin B12 is important for: 

  • Red blood cell formation 
  • DNA and protein synthesis
  • DNA methylation 
  • Development and functioning of the Central Nervous System (CNS)
  • Metabolism of amino acids and fatty acids
  • Improvement of immune system functions and responses 
  • Conversion of dietary carbohydrates into energy

Now, coming to the main part of the blog. 

Vitamin B12 Shots for Weight Loss 

A B12 shot is nothing but a large dose of vitamin B12. One B12 shot usually contains 1,000 mg of the stuff. These shots are usually given by a qualified doctor or nurse. But you can administer it yourself, similar to how diabetic people self-administer insulin. 

Doctors usually prescribe B12 injections for the treatment of vitamin B12 deficiency. One cause of B12 deficiency is Pernicious anemia, a disorder that causes a decline in RBCs when your intestines are unable to absorb enough vitamin B12.

So, how does it relate to weight loss?

As mentioned before, vitamin B12 is also known as cobalamin, which plays a major role in cell metabolism. This influences whether you feel tired or energetic. Increased energy is one of the promised perks of B12 injections. 

This enhanced energy may encourage you to go to the gym and engage in more physical activities. Apparently, you tend to work out harder as you won't feel fatigued but rather fully energetic. Meanwhile, you burn more calories! 

How do B12 Shots Work? 

Vitamin B12 deficiency happens when you have insufficient levels of this vitamin in your body. This deficiency can slow down, which then causes you to gain weight. Apparently, nearly half of Americans have low levels of Vitamin B12. 

This deficiency is very common among people who:

  • Who are over the age of 50.  
  • Are vegans and vegetarians
  • Have had undergone bariatric surgery (weight loss surgery)
  • Have gastrointestinal issues. 
  • Are suffering from anemia.

Even though changing your diet to incorporate more vitamin B12 is preferable, choosing B12 injections is a smart way to switch to a healthy lifestyle.

Bypassing the slower digesting process and entering your bloodstream directly, B12 injections provide you with a more powerful form of B12. This quick absorption helps you to take advantage of vitamin B12 faster. 

Benefits of Taking B12 Shots for Weight Loss

The biggest issue with taking B12 supplements or consuming B12-containing foods is that this vitamin is poorly absorbed in the bloodstream.

Moreover, in order to absorb high doses of B12 from food, you must take a considerable amount of high saturated fat animal-based products such as milk, cheese, and meat, which can lead to weight gain. 

One of the most effective methods of obtaining a healthy dose of B12 is to administer the vitamin directly into the bloodstream, skipping the entire digestive system. That is why vitamin B12 shots are so effective. Other benefits of B12 injections include: 

i) Enhanced metabolism – B12 shots are believed to speed up metabolism by assisting in converting food into energy. A slower metabolism may help you burn calories more efficiently, helping you to reach your weight loss goals.

ii) Increased Energy – B12 shots are great energy boosters! This is probably the main reason celebrities take these shots occasionally. This injection may motivate you to focus on your workout and gyms as well as improve your overall quality of life. 

iii) Appetite regulation – Some claim that B12 injections help control appetite by influencing the release of neurotransmitters that affect your hunger, which will prevent you from eating too much. 

Side Effects of Taking B12 Shots for Weight Loss

Vitamin B12 is generally considered safe to use for people with vitamin B12 deficiency. 

However, like any other supplement, B12 injections for weight loss also come with mild side effects. Some of the adverse side effects after taking B12 shots include:

  • Redness and pain in the injection site
  • Allergic reactions
  • Itching and skin rashes
  • Anaphylaxis
  • Pulmonary edema
  • High fever 
  • Numbness and joint pain 
  • Rapid weight gain 
  • Congestive heart failure
  • Polycythemia
  • Peripheral vascular thrombosis
  • Swollen tongue
  • Interaction with other medications

Make sure to have B12 shots for weight loss administered by a qualified healthcare practitioner. They will ensure a proper approach and monitor side effects.

How Does B12 Help with Weight Loss Directly? 

Again, if you've been diagnosed with a deficiency, B12 shots can help you lose weight.

Vitamin B12 is a water-soluble vitamin that comes in several forms. It also contains the mineral cobalt, which interacts with vitamin B12 activity in your body to form cobalamin. 

This comprises methylcobalamin deoxyadenosylcobalamin, which is an actively desired component in human metabolism.

Another important function of B12 is the conversion of carbohydrates to glucose. As you may know, glucose is the body's principal source of energy.

If you don't receive enough B12, you won't have enough energy to be active, which might lead to weight gain. Vitamin B12 also assists in the utilization of fat-derived energy.

What's more, this injection facilitates the conversion of the food you eat into glucose. Now, this glucose, which is a type of sugar, serves as a fuel source for the body to perform everyday tasks. To be able to function correctly, you must consume the appropriate quantity of this essential carb.

In case you're deficient in vitamin B12, your body isn't adequately breaking down the glucose you're consuming. Because of this, your body fails to get enough energy from the food you eat. 

Your body attempts to store extra fat as a reserve for energy as a result of this poor metabolism, which can lead to weight gain. This is how vitamin B12 injection is utilized to aid weight loss due to its connection with metabolism and energy provision. 

How Long Does the B12 Shot Last?

Although it's impossible to determine the exact duration, research suggests that if your body properly utilizes vitamin B12, it can remain in your body for up to five years. 

Of course, the actual injection will not stay in your body for that long since the vitamin is absorbed in the bloodstream. 

For those without a vitamin B12 deficiency, the majority of the vitamin B12 from an injection will be absorbed and quickly eliminated through urine. 

In contrast, those with a deficiency may store up to 50% of the vitamin in the liver, allowing them to feel the effects of the B12 shot for up to a month.

B12 Shot Alternatives for Weight Loss

There are always alternatives to something that may not work out as expected. Since B12 shots are not approved for weight loss, you can opt for other alternatives for your weight loss goals. They include:

1. Semaglutide (WegovyⓇ): 

Currently, Semaglutide is the only injection that the FDA approves for weight loss under the brand name Wegovy.

When combined with a well-balanced diet and exercise, Semaglutide may help reduce appetite and aid in weight loss. Semaglutide shots also help minimize the risk of diabetes, cancer, and heart disease in patients with obesity or overweight. 

2. Metformin:

Metformin (Fortamet, Glucophage, Riomet) is a common drug that doctors prescribe off-label for weight loss. It means the FDA hasn't approved this drug for weight loss, but some believe it works.

This medication helps some people lose a decent amount of weight and prevent further weight gain, which other B12 shots lack.

Metformin is usually prescribed for patients with type 2 diabetes. However, it can lead to Vitamin B-12 deficiency. So, if you are considering metformin for weight loss, talk to your doctor about strategies to maintain adequate B12 levels.

3. Ozempic: 

Ozempic is an FDA-approved prescription drug for the treatment of type 2 diabetes. However, it is not FDA-approved for weight loss purposes.

A few studies show that the active ingredient present in Ozempic, Semaglutide, which we discussed above, may definitely promote weight loss. So, this is another off-label drug you can consider. 

4. Lipotropic Injections:

A lipotropic injection is another effective alternative to B12 shots in case of weight loss. Many people confuse this with B12 injections since they contain vitamin B12 as one of their ingredients. 

These weight loss injections are supplements containing various vitamins and minerals that are believed to promote fat loss. Lipotropic shots are meant to be used as a complement to a weight loss routine, including diet and exercise. 

So, Should You Take B12 Injections For Weight Loss?

The short is No. 

Vitamin B12, in general, increases your energy. That being said, a B12 shot is not a strategy to lose weight, but surely, it may give you sufficient energy to burn more calories, but only if you have low levels of vitamin B12.

With this energy, you can start exercising and engaging in physical activities, which in turn may help you lose weight. Otherwise, it won't honestly make a difference. 

So, if you think you don't need B12 shots, then you probably shouldn't take them. After all, they won't do anything for you. Having more B12 does not provide any practical daily benefits once your stores are healthy.

But the plus point is that it won't harm your health even if you take it. Instead, you will just pee out excess B12 if not absorbed by your body. 

The Bottom Line

As you can see, there's no solid proof to confirm whether B12 shots for weight loss really work. Although they won't help in losing weight overnight, B12 injections can be a critical part of weight loss and management plans.

However, getting vitamin B12 through B12 shots is not likely to harm your health, but it can interfere with medications (if you're taking any) and make things worse. 

In short, if you're not deficient in the vitamin, B12 injections won't help you shed pounds or feel healthier. They only give you energy and boost your metabolism.

So, discuss with your healthcare provider before taking B12 shots for weight loss. Also, let them know if you're taking any nutritional supplements. 

If you're really hoping to lose some weight, don't go behind these quick and easy fixes. What really counts is following a calorie-controlled diet, a healthy lifestyle, and regular physical exercise.

The only genuine approach to shed your pounds is to create a calorie deficit. Burn more calories than you take in! 


1. How effective is a B12 shot for weight loss?

Ans: There's no proof that B12 shots help in weight loss. However, experts have said it can help speed up the metabolism by increasing B12 levels in the body. This leads to burning excess calories in the body. 

2. Can you inject B12 into belly fat? 

Ans: Yes. You can inject or self-administer B12 shots in any fatty area at least 2 inches below your belly button. Penetrate it into the fat below your skin so your body can quickly absorb the vitamin B12. 

3. What is the best injection for weight loss?

Ans: As of 2024, Semaglutide, under the brand name Wegovy, is considered the best injection for weight loss. The FDA has approved this, and it is safe for use. 

4. How often should you get a B12 shot for weight loss? 

Ans: Your healthcare practitioner will typically administer one B12 shot per week for weight loss. If you're deficient in B12, you may require two to three B12 injections for weight loss in a week. 

5. Where is the best place to inject B12 for weight loss? 

Ans: B12 shots for weight loss may be self-administered or administered by a doctor in the arm or other sites having excess subcutaneous fatty tissues like thighs, belly, or buttocks. 

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Oliver Nelson

Oliver Nelson is a New York based Health Specialist Writer who completed his graduation from Syracuse University back in 2015. His writings were published in the top Healthcare brands in the United States.

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