B12 allows red blood cells to carry more oxygen giving a person more energy. Great to combine with an HCG diet, sickness, or just sluggish. B12 not only promotes energy but enhances an individual's mood. B12 is an essential element in the breakdown of fat tissue, so it is a key component in weight loss as well
Because of B12 overall use in the body it also helps muscle recovery. As well as energy, mood, fat synthesis, B12 also helps absorption of other key nutrients. Since B12 is a vitamin it is not harmful for your body, so taking too much will never be a problem.
I personally keep B12 in my medicine cabinet and use it regularly for sluggish or sick days as it is a great enhancer to help you get over the hump.