When your body is unable to use carbs, it uses fatty acids and ketones to create necessary energy for your body, this is what helps you lose weight. (wisejug.com)
Since vitamin B12 works to provide your body with necessary energy, therefore, using it will keep you energetic. (fitnessedge.net)
These guidelines were developed to eliminate the problem of choosing equipment that is oversized and that contributes to higher than necessary energy consumption. (energystar.gov)