B12 Injections For Metabolism & Weight Loss: Does It Help?

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B12 Injections For Metabolism & Weight Loss

Since time immemorial, experts have debated on whether or not B12 injections for metabolism and weight loss are effective for individuals who want to shed weight. Some propose that B12 exhibits positive results on weight loss regardless of a deficiency. 

Using supplements helps boost your energy, heightens your metabolism, improves your sleep cycles, and heightens your mood. If you’re thinking of getting a B12 injection, keep reading to find out if B12 shots are the way to go as far as weight loss is concerned. 

What Does B12 Do to Your Metabolism?

You can take a B12 shot to assist your body in functioning more effectively. Here are some of its benefits:

  • Eliminates anemia
  • Contributes to healthy bones
  • Boosts energy
  • Enhances beauty
  • Promotes healthy eyesight
  • Improves mood

Eliminates Anemia

Anemia is a deficiency of red blood cells in the blood. It’s generally associated with a low iron count or a lack of B12. Anemia causes people to feel exhausted most of the time and develop difficulties in breathing. 

B12 shots mainly help to fight anemia by increasing your red blood cells. With constant treatment, most people find that they neither feel weak or fatigued. Others even report improvement in their lung function after taking B12 treatments. 

Contributes to Healthy Bones

A B12 promotes healthy bones and helps keep your body more agile and robust. Studies reveal that B12 helps in boosting the number of minerals within your bones, thus making them less prone to severe breakage. B12 also fortifies your bones against serious damage. 

Individuals with a healthy level of B12 in their system are less likely to encounter osteoporosis in the future. B12 injections are mostly recommended for women since they have a higher risk of osteoporosis than their male counterparts. 

Boosts Energy

If you feel like you’re tired all the time, and your energy levels are plummeting,  that’s a sign of low levels of Vitamin B. A quick round of B12 will help you feel renewed and fresh. 

Because anemia is one of the most noticeable symptoms of B12 deficiency, it stands to reason that people who boost their B12 intake will feel more perky and energetic. Those who don’t portray anemia signs may also benefit from the injection. 

Enhances Beauty

Consistent B12 injections can also make you more attractive by strengthening your skin, nails, and hair. B12 develops new cells within your body. Because of that, taking a B12 injection increases the turnover of old cells, thus giving you a flawless complexion and attractive nails. 

Most people who take B12 shots notice that their hair texture is thicker and more lustrous. B12 has a solid connection to beauty to the point that it’s sold over the counter and even marketed as a beauty supplement. You can enjoy its benefits more effectively and quickly through injections. 

Promotes Healthy Eyesight

Receiving B12 helps you maintain your crystal-clear eyesight even in your later years. It’s been proven to tackle macular degeneration and offer you clearer vision. 

Macular degeneration is a condition that affects most people as they grow older. In the worst-case scenarios, it might even lead to mobility issues. By taking B12 shots as early as now, you can keep your eyes in tip-top condition and enjoy all other benefits as well. 

What is B12? 

B12 is a water-soluble vitamin in prescribed medication, dietary supplements, fortified processed foods, or animal-based products. Otherwise referred to as cobalamin, Vitamin B12 is actively involved in cell metabolism in the human body. 

As one of the eight B vitamins, Vitamin B12 is a significant part of the DNA synthesis and the metabolism of both amino and fatty acids. This metabolic activity means that without proper absorption and consumption of B12, the human body can’t metabolize carbohydrates and fats. 

Vitamin B12’s major functions in the body include:

  • Supporting red blood cell development
  • Boosting immune functions and reactions
  • Strengthening the nervous system and brain

What Are Some Common Signs of Vitamin B12 Deficiency? 

Vitamin B12 deficiency often leads to megaloblastic anemia. It’s characterized by a low count of red blood cells that are usually bigger than average. Megaloblastic anemia causes a variety of side effects and symptoms such as:

  • Poor balance
  • Headache
  • Shortness of breath
  • Memory loss
  • Rapid heart palpitations
  • Fatigue

Please note that low Vitamin B12 levels don’t always lead to megaloblastic anemia. Most people might report mild symptoms such as fatigue. In addition, while a vitamin B12 deficiency may not lead to weight gain, it may lower energy levels and even result in fatigue. This deficiency will make it more challenging to manage your weight and stay active. 

Some studies[1] also show that a drop in Vitamin B12 might lead to appetite loss, sometimes resulting in weight loss if left untreated. If you’re deficient in B12[2], your healthcare provider may recommend oral vitamin B12 injections or supplements to boost your blood levels. You could also eat foods rich in B12 (meat, fish, milk, cheese, etc.) to prevent megaloblastic anemia. 

What is B12 Injection? 

Because the human body is incapable of making B12 on its own, we need to source it from daily/weekly/monthly supplements or food sources. 

Foods that contain Vitamin B12 include dairy products such as cheese, milk, eggs, meat, and fish. Vegetarians and others who don’t consume animal products often get their B12 supply from vitamin supplements and fortified cereals. 

Your RDI (recommended daily intake) may differ based on medical factors such as your diet and age. Overall, a healthy adult’s RDI for vitamin B12 ranges from between 2.4 to 2.8 mcg. 

While changing your dietary habits to factor in more B12 is a worthy idea, injections are the ideal way to go back to a healthier lifestyle. Because you’re receiving a purer form of B12 via injection, it will flow straight into your bloodstream rather than the slower digestion process. This rapid absorption helps you enjoy the benefits of B12 much sooner. 

Effects of B12 on Metabolism and Fat

Despite the limited research on B12 in human beings, many studies suggest that vitamin B12 could affect metabolism and body fat. 

B12 plays a crucial role in fat metabolism. A deficiency could be associated with obesity and heightened fat accumulation. An animal study[3] revealed that severe vitamin B12 deficiency led to a considerable increase in cholesterol levels and body fat percentage in pregnant mice. 

Another study[4] found that giving B12 vitamins to rats with a high-fat diet lowered weight gain and boosted levels of different enzymes that affect metabolism. 

Interestingly, different studies have revealed that an adequate vitamin B12 level is associated with lower risks of obesity and weight gain. Based on research done on 9,075 people, having higher vitamin B12 levels was linked to lower risks of obesity. 

Similarly, a study[5] on 256 children showed that those with lower B12 levels tended to have a bigger BMI (body mass index), which measures body size based on weight and height. 

However, remember that while these studies reveal a link between body weight and vitamin B12 status, no other potentially contributing factors are considered. Thus, it’s impossible to assume that B12 leads to weight loss. Further research needs to be done to ascertain that B12 affects BMI or body weight. 

Final Thoughts

Vitamin B12 is essential in several health aspects, including heart health, brain function, and the development of DNA and red blood cells. 

You’ll be glad to know that there are no major risks linked to taking huge amounts of the B12 vitamin in your bid to lose weight. There are, therefore, no known side effects of taking B12 shots. If you have a phobia of sharp objects, not worry. B12 supplements also occur in various forms, including lozenges, liquids, capsules, and tablets. 

While a B12 injection may offer noticeable results, your body should undergo a form of vitamin deficiency in order to make a difference. However, it’s unclear if Vitamin B12 may have any effect on your weight loss if you’re already incorporating enough B12 in your diet. B12 is prevalent in fortified foods and animal products. 

So is a B12 shot necessary for weight loss? Practically speaking, no. In order to shed a few pounds, you need to adopt an active lifestyle and improve your diet. Focus more on making changes to your diet. Consuming foods with rich Vitamin B12 content will increase your chances of losing fat exponentially. 


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  1. Wolffenbuttel, B.H.R., Wouters, H.J.C.M., Heiner-Fokkema, M.R. and van der Klauw, M.M. (2019). The Many Faces of Cobalamin (Vitamin B12) Deficiency. Mayo Clinic Proceedings: Innovations, Quality & Outcomes, [online] 3(2), pp.200–214. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6543499/ [Accessed 12 Oct. 2021].
  2. ‌Nagao, T. and Hirokawa, M. (2017). Diagnosis and treatment of macrocytic anemias in adults. Journal of General and Family Medicine, [online] 18(5), pp.200–204. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5689413/ [Accessed 12 Oct. 2021].
  3. ‌Ghosh, S., Sinha, J.K., Putcha, U.K. and Raghunath, M. (2016). Severe but Not Moderate Vitamin B12 Deficiency Impairs Lipid Profile, Induces Adiposity, and Leads to Adverse Gestational Outcome in Female C57BL/6 Mice. Frontiers in Nutrition, [online] 3. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4722109/ [Accessed 12 Oct. 2021].
  4. ‌Zheng, Y., Ma, A., Zheng, M., Wang, Q., Liang, H., Han, X. and Schouten, E.G. (2018). B Vitamins Can Reduce Body Weight Gain by Increasing Metabolism-related Enzyme Activities in Rats Fed on a High-Fat Diet. Current Medical Science, [online] 38(1), pp.174–183. Available at: https://pubmed.ncbi.nlm.nih.gov/30074168/ [Accessed 12 Oct. 2021].
  5. Ozer S;Sonmezgoz E;Demir O (2017). Negative correlation among vitamin B12 levels, obesity severity and metabolic syndrome in obese children: A case control study. JPMA. The Journal of the Pakistan Medical Association, [online] 67(11). Available at: https://pubmed.ncbi.nlm.nih.gov/29171553/ [Accessed 12 Oct. 2021].

Medically reviewed by:

Lisandra Fields is a freelance medical writer from Pennsylvania who creates articles, blog posts, fact sheets, and website content for health-related organizations across North America. She has experience working with a wide range of clients, from health charities to businesses to media outlets. She has experience writing about cancer, diabetes, ALS, cannabis, personality psychology, and COVID-19, among many other topics. Lisandra enjoys reading scientific journal articles, and finding creative ways to distil the ideas for a general audience.

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