The Theory of Planned Behavior was initially offered by Icek Ajzen in 1985. The theory is based on the Theory of Reasoned Action offered by the same scientists ten years earlier, and actually represents the continuation and expansion of it. This theory was based on different theories and stated that if individuals assess the recommended actions as helpful, and if they listen to the people they consider to be important to them, this leads to the formation of the definite purpose. A fact that the attitudes and individual conditions and behavioral objective are closely connected was proved by many investigations.However, there is still an opposing idea that was offered after some of the investigations were held. This idea implies that behavioral objective does not always result in the real performance of due to the different limitations. Specifically, in view of the fact that behavioral objective can’t determine the future way of actions in case if the person does not implement the needed control over his actions, Icek Ajzen offered the Theory of Planned Behavior where he added a construct called perceived behavioral control (PBC). This way the scientist improved his previous Theory of Reasoned Action because it was determined that with the help of the Theory of Planned Behavior it is really possible to forecast behavior connected with people’s health.The TPB model represents a very effective instrument for analyzing people’s behavior. Therefore, it is widely applied in the investigations connected with health. The TPB is often used by the investigators in order to define obesity factors in fat people.