There can be various ways of viewing and responding to the same matter from different people. Similarly our body and its ailments are viewed , studies and responded by different people in different ways. So we have Ayurveda, Homeopathy, Allopathy, Unani and many other systems of treatment and cure for body ailments. However the aim of all these systems are to bring back the person to his normal health and routine.
Allopathy approach is that ailments are caused by external causes and the treatment is in resisting, attacking and eliminating the cause and assisting body to gain its normalcy. So it applies contra force to put the patient to ease immediately.
Homeopathy approach is to move with the cause and bring it out in the open and then nullify the cause by giving medicine.
Ayurveda in a quite different way looks any ailment of the body as the imbalance of the three basic factors in the body. So as per Ayurveda the cause is in the body itself. Thus the treatment is only the same food that one takes - by adopting some regulation, that is all. That is why even fasting is prescribed as treatment in Ayurveda.
As the cause is seen in the body itself, Ayurveda studies everything that is put into the body and categorises how each one behaves, so that proper balancing or control and moderation can be maintained. Body is like an engine. The energy is produced by degeneration and chemical reactions undergoing in the body and heat is produced. But the body heat is maintained by body's thermostat mechanisms. Just as different fuels produce different heat output on combustion, different foods also produce different heat output inside body. Ayurveda follows this. The study has been made and the ready to use directions kept available for us by our ancient Rishis and Acharyas.
Ayurveda treat such heat as 'Agni". The heat or Agni that is generated inside the stomach side is called 'Jataragni" and there are various other types of Agni as classified by various Rishis or Ayurveda Acharyas.
Heat or Agnis is the basic energy that is used for various activities inside our body including digestion, circulation etc.etc.
Other system practitioners also advise patients to desist or regulate certain foods and take more certain foods( as prescribe in Ayurveda system), but they do not ascribe the reason as heat or Agni. They may reason it in different ways.
Actualy Ayurveda is a well developed and well studies system of health maintenance thousands of years before Allopathy was even born. It gets more wider acceptance in modern days.