Composition

• The composition that makes up vitamin B complex consists of several B vitamins, including B1, B2, B3, B5, B6, B9 and B12.
  
  

Function

• This vitamin can assist with weight loss because it ensures proper metabolism functions, helps the cells to use energy and assists with food digestion.
  
  

Food Sources

• Food sources that contain vitamin B include cereals, grains, nuts, fruits and leafy vegetables. Meats such as chicken and fish are good sources, along with eggs. Yogurt, cheese and other dairy products also contain vitamin B.
  
  

Supplements

• Though it generally is better to get daily amounts of vitamin B in the foods you eat, some people prefer to take a supplement. Vitamin B complex is available in pill form in different dosages at most health and vitamin stores.
  
  

Injections

• Some doctors also administer a shot consisting of vitamin B complex for weight loss patients. This shot usually is given in connection with a medically-supervised diet and exercise plan.
  
  

Warning

• People usually do not experience side effects with taking vitamin B complex, but too much of it may cause side effects such as vomiting, diarrhea, irregular heartbeat and liver problems.