B12 for Weight Loss

B12 for Weight Loss - Shots vs Natural Sources and Supplementation

7 min read


06 Jun 2019

Vitamin B12 and weight loss are being increasingly linked in the media. Some claim that taking high-dose shots of the nutrient can help people to shift excess weight. There are stories of people feeling more energetic and becoming more active as a result. But is there any evidence to back up the B12 weight loss claims?

If you’re trying to lose weight, then you may have considered trying B12 as an option. The idea of taking a vitamin that aids your slimming efforts can be particularly appealing. Vitamin B12 is something that most of us have heard of and seen on ingredient labels, so it feels like a supplement we can trust. But if you’re wondering whether it can help you lose weight, then it’s important to do your research. In this article, we present the evidence-based facts so you can decide if it’s right for you.

What Is Vitamin B12? 

Vitamin B12 is a key nutrient that’s essential for human health. It plays a role in lots of different processes such as producing energy, metabolizing carbohydrates, and forming red blood cells (which transport oxygen around). It’s one of the B-vitamin group which also includes Niacin, Riboflavin, Biotin, and Folic Acid. Without enough of it, people can experience symptoms such as tiredness, lethargy, or suffer from megaloblastic anemia. Because animal products are key sources, people following a vegetarian or vegan diet can sometimes find themselves with deficiencies.

Main Functions of Vitamin B12

Vitamin B12 is fundamental for us to feel and function at our best. It keeps red blood cells and nerves healthy which affect every area of our body. It’s also involved in the formation of DNA which is what keeps our cells growing and dividing as they should. Here are some of the many ways in which B12 benefits our health: 

  • Red blood cells – supports their formation which allows oxygen to be transported around the body
  • Nerves – keeps them healthy so that signals can be transmitted between the brain, limbs, and rest of the system
  • DNA – plays a role in DNA and RNA creation so that genetic code is able to support cell reproduction
  • Anemia – helps to treat megaloblastic anemia which can make people feel tired, weak, and lethargic
  • Enzymes – kick-starts 100+ tiny chemical reactions in the body by behaving as a co-factor for enzymes 

Why Is Vitamin B12 Linked to Weight Loss?

When it comes to talking about B12 weight loss, it’s the enzyme influence that’s most interesting. This vitamin is co-factor in the conversion of homocysteine into methionine. This essential amino acid is central to numerous elements of our health, including fat metabolism. Without enough B12, the body can’t produce enough methionine which means it can’t break fat down very well. This is one of the reasons that people have suggested B12 can aid weight loss.

However, scientific research on the topic is very limited. One found that low vitamin B12 levels were associated with obesity. However, it didn’t establish a causal link between the two so it’s not clear if low B12 causes people to gain weight or if gaining weight causes lower B12 levels. Or if the association is simply down to pure chance! 

The vitamin has been shown to boost energy levels which could lead to someone being more physically active as a result. This may indirectly support weight loss as part of a healthy lifestyle. have also suggested that vitamin B12 can reduce the amount of weight gained by overweight and obese people (but not stop or reverse it).

There is an argument that B12 benefits weight loss in those who are deficient. But according to government data, this is less than 6% of the American population. There’s little research to suggest that it’s effective in the 94% of healthy adults with sufficient B12 levels. 

The Best Sources of Vitamin B12 

Sources of Vitamin B12

Food is the main source of vitamin B12 for most people. It’s found in many animal products and some foods are fortified with it too. The best sources include: 

  • Meat
  • Poultry
  • Shellfish
  • Eggs
  • Fortified plant milks
  • Fortified cereals
  • Nutritional yeast

The Effective Dose of B12 For Weight Loss

At this point, you might be wondering, how much B12 should I take for weight loss? Is there a minimum dose that’s needed for it to be effective? Based on current evidence, you just need to take enough to avoid deficiency. This will enable your body to metabolize fat in the normal way and keep your energy levels up. For most people, the recommended daily intake of B12 is 2.4mcg. 

How To Get More Vitamin B12

If you’re looking to increase your vitamin B12 levels, then there are several options available to you. Adapting your diet, using supplements, or getting a B12 shot can all help to give you a nutrient boost. Let’s look at these options in more detail.


 The consumption of meat and dairy products is how most people get B12 from their diet. Eating chicken, beef, liver, cheese, and yogurt will help to keep your levels healthy. But not everyone can eat these foods, either for ethical or health reasons. If you follow a vegan or vegetarian diet, then it’s important to be proactive about your B12 consumption. It’s not easy to make up the deficit caused by avoiding animal products so you’ll need to make a conscious effort to consume more B12 from other food sources.

Likewise, people with lactose intolerances who can’t consume dairy should also make an effort to eat more B12. Looking for fortified cereals and plant milks is an easy way to do this.


If you’re not eating foods that are rich in B12, then taking supplements may be beneficial. A daily multi-vitamin tablet or powder can ensure that your body is getting enough on a consistent basis. However, if you suffer from a condition like Crohn’s disease, pernicious anemia, or anything that results in digestive malabsorption, then a dietary supplement may not have much effect. Any tablets you take probably won’t be absorbed by the digestive system (or at least not in the quantities that your body needs). You may find that a supplement patch that’s worn on the skin or injection delivers a greater vitamin-boosting benefit in these cases. 


Vitamin B12 is also available as a high dose injection. This type of shot is designed for people who are deficient and need to increase their levels quickly. It involves having the vitamin injected into muscular tissue on alternate days for a two-week period. Depending on the improvement that’s seen, further injections are then administered every 1-3 months. This type of shot requires a prescription and is delivered by a qualified medical professional. 

B12 Injections Vs Diet and Supplements 

Some companies also offer B12 shots for weight loss but that’s not what they’re designed for. Shots are intended to boost levels in people with a chronic deficiency. There’s little evidence to suggest that they are an effective aid for weight loss in healthy people. For the majority of the population, eating a balanced diet and taking a multi-vitamin is a better (and cheaper) alternative.

If you are experiencing the signs or symptoms of , then it’s important to see a doctor. They can measure your levels, diagnose you properly, and advise you on the best course of action. For people who are chronically deficient, shots are a quick and effective way to rebalance B12 levels. But for those who want to lose weight, they haven’t proven to have any beneficial effect.

Vitamin B12 and Weight Loss – Summary 

There are lots of vitamin B12 weight loss claims floating about on the internet. Supporters believe that it boosts fat metabolism which makes it easier to shift those troublesome excess pounds. However, there is very little evidence to demonstrate that supplementing with this nutrient helps to reduce body mass. Although some companies offer B12 injections for weight loss, their products don’t appear to be supported with scientific studies.

If you are trying to lose weight, then it’s best to stick with proven approaches. Adopting a healthy diet and exercising regularly are tried and tested methods for reducing body fat. If you do need a little help, then can give your energy levels and fat-burning capacity a boost. It contains ingredients that are scientifically proven to contribute to weight loss, suppress appetite, and improve mood.