Vitamin B-12 is one of the eight B complex vitamins that's essential for energy production and the health of your central nervous system. If you're deficient in vitamin B-12, your doctor might recommend supplemental pills or injections to get your health back on track. The pills are sometimes included as part of a weight-loss protocol to promote energy and boost your metabolism. While supplemental B-12 might give you more energy if it corrects an underlying deficiency, there's no evidence that extra vitamin B-12 will help you lose weight.
About Vitamin B-12
Vitamin B-12 is also known as cobalamin. Along with the other B vitamins, it helps you convert the food you eat into fuel. B-12 is found naturally in animal foods, such as fish, dairy, eggs, beef and pork, and some breakfast cereals are fortified with vitamin B-12. When you get too little B-12, or your body doesn't absorb it properly, you can become anemic and suffer from fatigue, weakness, numbness, shortness of breath and tingling in the hands and feet.
Most people get enough B-12 through their diet, but some people — older adults, strict vegetarians and vegans and those who've undergone weight-loss surgery — are sometimes at risk of deficiency. For these populations, vitamin B-12 pills may help correct the problem so they look and feel better after taking them, but the pills don't cause them to lose weight.
Vitamin B-12 Supplemental Pills or Injections
Your doctor might prescribe vitamin B-12 if you've been diagnosed with pernicious anemia. In this type of anemia, your stomach doesn't produce enough of a substance called intrinsic factor that helps you absorb vitamin B-12 from food. High-dose pills or injections help you get enough vitamin B-12 for normal function.
Sometimes vitamin B-12 is prescribed to lower the amount of homocysteine, an amino acid, in the blood because high levels are a potential risk for heart disease. Some research also supports using supplemental B vitamins, including B-12, to reduce risk of macular degeneration, a serious eye disease, but more research into the effectiveness of B-12 is needed.
Vitamin B-12 and Energy
Vitamin B-12 deficiency can lead to long-term problems with cognition, memory, balance and nerve function. A deficiency of the vitamin can also cause weight loss. If your B-12 levels are normal, however, getting more from supplemental pills or injections won't promote weight loss or give you more energy.
Taking too much supplemental vitamin B-12 for a long period of time can cause an imbalance in your body's level of all the B vitamins. B-12 supplements should only be taken under the advisement of a doctor because of their potential to conflict with a number of medicines, including certain antibiotics and medications used to treat diabetes, acid reflux and stomach ulcers.
Food to Maximize B-12 Intake and Lose Weight
If you suspect you're deficient in vitamin B-12, consult with your doctor. You could also increase your intake of foods rich in B-12, such as organ meats, clams and meats, as they contain other vitamins and minerals that offer health benefits.
If you want to lose weight, though, vitamin B-12 pills are not the answer. Instead, eat a whole-foods, portion-controlled diet, and get some regular exercise. A pound of fat equals 3,500 calories, so if you can trim 500 to 1,000 calories from your meals daily, you'll lose 1 to 2 pounds per week. Regular cardiovascular exercise and strength training also support weight management more effectively than any kind of supplemental vitamin pill.