Dosage For B12 Injections For Weight Loss


Are you looking for dosage for B12 injections for weight loss? B12 is known to be a great addition to your diet especially if you are trying to shed some pounds. This is because, in addition to being a fat burner, it is also a great energy booster.

What Is Vitamin B12?

Vitamin B12 is a water-soluble vitamin required by the body in order to function properly. It is vital in a number of different biological processes. These processes include DNA synthesis, red blood cell formation, energy production, nerve cell health, and general neurological function.

How Can I Tell If I Should Consider B12 Injections?

There are a number of reasons that you might wish to seek out vitamin B12 injections. You might be suffering the symptoms of B12 deficiency, or you might know that you are at increased risk of B12 deficiency as a result of hereditary factors or other health conditions.

What Factors Lead to B12 Deficiency?


Any illness or condition that affects the digestive system can result in a B12 deficiency because the vitamin is bound to the protein molecules in your food and is released and absorbed by the body during digestion. Such conditions include autoimmune conditions such as Crohn’s disease, celiac disease and ulcerative colitis, which all prevent the body from adequately absorbing nutrients from the intestines.

Additionally, other factors such as having had gastric bypass surgery or taking antacids long-term can lead to deficiency. This is because adequate exposure to stomach acid is needed to help the body absorb B12.

Lifestyle Choices

You are also significantly more likely to suffer from B12 deficiency if you practice a vegan diet and lifestyle. This is because there are few vegan foods that contain B12 and also because the body finds it significantly more difficult to absorb B12 from the few vegan sources that have it.  Many foods are fortified with artificial vitamin B12, such as non-dairy milks and cereals, but these are not always optimally absorbed, so vegans must still be proactive about making sure they are not becoming deficient.


You are more likely to be B12 deficient if you are over the age of 65, as the body becomes less efficient at absorbing nutrients as you go on in life.

Benefits of B12 Shots and Injections

Without a doubt, I’m sure you are aware of Vitamin B12. 

It is THE energy vitamin people take if they are feeling fatigued.

It’s in just about every energy drink, energy supplement and any type of food or beverage that claims to “boost” energy.

But it is so much more than simply an “energy boosting vitamin”. 

It’s actually critical to a number of vital cellular functions and believe it or not, despite the fact that it is inside so many beverages and foods, there is still a high chance that you aren’t getting enough.

We will talk about this a little bit later, but it turns out that Vitamin B12 must go through several steps before it is properly absorbed through your GI tract and several hormone imbalances (including thyroid) can alter this absorption.

This can put you in the tricky situation where your body may be getting “enough” in your diet, and yet it isn’t absorbing it completely.

In addition to this, many people have problems metabolizing B12 in the low-quality forms like Cyanocobalamin due to defects in the MTHFR gene (1) (as many as 40% of people have THIS problem!).

Another big issue is Hypothyroidism. 

As many as 40-50% of Hypothyroid patients have a B12 deficiency (2). 

It also may surprise you that medications can deplete your vitamin B12 levels – I’m looking at you Metformin 

I’m not saying any of this to scare you or to concern you, but to simply bring it to your attention that Vitamin B12 deficiency is a big deal.

It’s also really important to understand that HOW you take vitamin B12 can make a huge difference.

If you have any sort of GI issue (GERD, reflux, SIBO/SIFO, yeast problems, chronic constipation, etc.) you will have problems taking oral forms of vitamin B12.

Yes, that includes sublingual forms of B12 as well.

This may explain why so many people say they feel amazing when taking vitamin B12 shots and injections even if they were taking oral forms of vitamin B12 previously. 

Symptoms of Vitamin B12 Deficiency

Initially, the symptoms of B12 deficiency can be difficult to notice. Some of the most common symptoms are easily confused with general tiredness, diet change, lifestyle change, or weight loss. These include fatigue and lethargy, feeling irritable, faintness, and headache.

However, some symptoms are more noticeable, such as memory issues, difficulty maintaining your balance, mouth ulcers, a sore, swollen tongue, and heart palpitations. If you have been experiencing any of these symptoms for an extended period of time, or a number of these symptoms together, then you should not delay in consulting with us.

Like many other nutrient deficiencies, it turns out that blood work really isn’t the best way to determine if you are deficient. 

Many nutrients have their action INSIDE the cell, which means that testing serum and blood levels just give us an indication of what may be available – but that is assuming everything else is working properly: cellular activity, enzyme activity, receptor activity, etc.

Luckily there are other ways to determine deficiencies (we will go over lab work below) like your symptoms.

Because vitamin B12 has a wide array of cellular actions the symptoms of deficiency are quite diverse. 

Symptoms of vitamin B12 deficiency may include any or all of the following:

  • Chronic fatigue  or low energy (despite getting enough sleep)
  • Shortness of Breath
  • Macrocytic anemia 
  • High MCV (mean corpuscular volume on CBC analysis) 
  • Neurological changes that can mimic dementia 
  • Depression (7), Anxiety and other mood disorders
  • Difficulty with concentration
  • Brain fog
  • Skin changes like hyperpigmentation, Vitiligo or angular stomatitis
  • Hair changes (including hair loss (

Perhaps you can relate to one or more of these symptoms noted above? 

Maybe you’ve tried vitamin B12 sublingual or other oral forms? 

Maybe you still have symptoms?

In either event, the fact remains:

Vitamin B12 is a serious deficiency that can lead to multiple negative side effects.

Not only that but it’s estimated that up to 20% of the US population  has vitamin B12 deficiency!

So why is it that up to 40% of patients can have a subclinical vitamin B12 deficiency?

Like many other nutrient deficiencies and complex medical problems, it boils down to physician and patient oversimplification of the problem.

Why do you need vitamin B12?

Vitamin B12 is an essential nutrient that plays a critical role in several of your body’s processes.

It’s necessary for proper red blood cell production, DNA formation, nerve function, and metabolism

Vitamin B12 also plays a key role in reducing levels of an amino acid called homocysteine, high levels of which have been linked to chronic conditions like heart disease, stroke, and Alzheimer’s

Additionally, vitamin B12 is important for energy production. However, there’s currently no evidence that taking B12 supplements increases energy levels in people who are not deficient in this nutrient

Vitamin B12 is found mostly in animal products, including meats, seafood, dairy products, and eggs. It’s also added to some processed foods, such as cereal and nondairy milk.

Because your body can store B12 for several years, serious B12 deficiency is rare, but up to 26% of the population may have a mild deficiency. Over time, B12 deficiency can lead to complications like anemia, nerve damage, and fatigue.

Vitamin B12 deficiency can be caused by not getting enough of this vitamin through your diet, problems with absorbing it, or taking a medication that interferes with its absorption

The following factors may put you at a higher risk of not getting enough vitamin B12 from diet alone

  • following a vegetarian or vegan diet
  • being over 50 years old
  • gastrointestinal disorders, including Crohn’s disease and celiac disease
  • surgery on the digestive tract, such as weight loss surgery or bowel resection
  • metformin and acid-reducing medications
  • specific genetic mutations, such as MTHFR, MTRR, and CBS
  • regular consumption of alcoholic beverages

If you’re at risk of deficiency, taking a supplement may help you meet your needs.


Vitamin B12 is an important nutrient that plays a critical role in your body. It’s mainly found in animal products, and some people may be at risk of not getting enough from diet alone.

Suggested dosages

The recommended daily intake (RDI) for vitamin B12 for people over 14 is 2.4 mcg

However, you may want to take more or less, depending on your age, lifestyle, and specific situation.

Note that the percent of vitamin B12 your body can absorb from supplements is not very high — it’s estimated that your body only absorbs 10 mcg of a 500-mcg B12 supplement

Here are some recommendations for B12 dosages for specific circumstances.

Adults under age 50

For people over 14, the RDI for vitamin B12 is 2.4 mcg (1Trusted Source).

Most people meet this requirement through diet.

For example, if you ate two eggs for breakfast (1.2 mcg of B12), 3 ounces (85 grams) of tuna for lunch (2.5 mcg of B12), and 3 ounces (85 grams) of beef for dinner (1.4 mcg of B12), you would consume more than double your daily B12 needs

Therefore, supplementing with B12 is not recommended for healthy people in this age group.

However, if you have any of the factors described above that interfere with vitamin B12 intake or absorption, you may want to consider taking a supplement.

Adults over age 50

Older people are more susceptible to vitamin B12 deficiency. While relatively few younger adults are deficient in B12, up to 62% of adults over the age of 65 have less than optimal blood levels of this nutrient

As you age, your body naturally makes less stomach acid and intrinsic factor — both of which can affect the absorption of vitamin B12.

Stomach acid is necessary to access the vitamin B12 found naturally in food, and intrinsic factor is required for its absorption.

Due to this increased risk of poor absorption, the National Academy of Medicine recommends that adults over the age of 50 meet most of their vitamin B12 needs through supplements and fortified foods

In one 8-week study in 100 older adults, supplementing with 500 mcg of vitamin B12 were found to normalize B12 levels in 90% of participants. Higher doses of up to 1,000 mcg (1 mg) may be necessary for some

Pregnant women

Pregnant women have slightly higher vitamin B12 needs than the general population.

Low maternal levels of this vitamin have been associated with birth defects in infants

Additionally, a large systematic review showed that B12 deficiency is associated with a higher risk of premature birth and low birth weight in newborns

Therefore, the RDI for vitamin B12 during pregnancy is 2.6 mcg. This level can be met through diet alone or with a prenatal vitamin 

Breastfeeding women

Vitamin B12 deficiency in breastfed infants has been linked to developmental delay

Additionally, B12 deficiency in infants can lead to irritability, decreased appetite, and failure to thrive

For these reasons, the RDI for this vitamin for breastfeeding women is higher than that for pregnant women — namely 2.8 mcg

Vegetarians and vegans

Vitamin B12 recommendations do not differ for people following a plant-based diet.

However, the RDI of 2.4 mcg for people under 50 years of age is much harder to meet on a vegetarian or vegan diet

In a review of 40 studies on vitamin B12 in vegetarians, up to 86.5% of vegetarian adults — including older adults — were found to have low levels of vitamin B12

There are currently no government recommendations for B12 supplement dosages for vegetarians.

However, one study suggests that doses up to 6 mcg of vitamin B12 per day may be appropriate for vegans

B12 for improved energy

Though vitamin B12 is commonly taken to increase energy levels, evidence showing that B12 supplements improve energy levels in people without a deficiency is lacking.

However, B12 supplements have been found to improve energy levels in those who are deficient in this nutrient

One review recommended that those with vitamin B12 deficiency take 1 mg of vitamin B12 daily for a month, followed by a maintenance dose of 125–250 mcg per day

People who have issues absorbing vitamin B12, such as those with Crohn’s disease or other gastrointestinal issues, may benefit from B12 injections, which bypass the need for absorption by the digestive tract

B12 for memory and mood

It’s commonly thought that taking vitamin B12 can boost your memory and mood. However, there’s not a lot of evidence to support this theory.

Animal studies suggest that vitamin B12 deficiency has been associated with memory impairment. Yet, there’s currently no evidence that B12 supplements improve memory in humans who aren’t deficient

In a large review, vitamin B12 supplements had no effect on depressive symptoms in the short term but may help prevent relapse over the long term

There are no specific dosage recommendations for B12 supplements for mental performance or mood.


Optimal dosing of vitamin B12 varies by age, lifestyle, and dietary needs. The general recommendation for adults is 2.4 mcg. Older adults, as well as pregnant and breastfeeding women, require higher doses

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