Importance  of fat  synthesis  and storage : As  is clear from above  account, all  surplus nutrients, digested and  absorbed  from above the  immediate need of  body, are readily  converted to fat and stored, Normally  about 200 times  more  energy is stored as fat than  as glycogen ,Storge of fat for energy ( reserve food ) is very advantageous for following  reasons:

1.      It helps  in maintaining  normal concentrations   of all mutrients in the  blood.

2.      While  glycogen storage capacity liver  muscles and other body cells  is limited fat storage capacity    of major  adipose tissues is unlimited,

3.      Fats   are concerntrated  food reserves requiring  less  space for storage. Hence  fat storage  is economical.

4.      Since  fat  contains  more of hydrogen and less  of oxygen  a given  weight  of fat yield  about 2.25 times  more energy than that  of carbohydrates or proteins.

Hormonal  control  of fat metabolism: Insulin   hormone  promotes  fat storage,  whereas  contisol  thyroxine  epinephrine  and growth  hormone stimulate degradation  of fats  for energy production,

Obesity  If blood  in excess  of the requirement  of body  is taken  continuously .i.e.  energy  input  or agin  is  continuously  more  than energy output  or expenditure. Fat  storage swells  resulting  into  fattening  of the  body  and increase in its  weight. This  is called  obesity.

Atherosclerosis: It is a disease of  arteries in which  fatty  lesions,,called  atheromatous  plaques,  develop  upon  the inside  of arterial wall  by deposition  of cholesterol connective tissue  fibres  and often  calcium  salts, This  causes hardening  of the arteries blocking  of blood  flow  in these extensive  damage to  arterial wall, hemorrhage ,thrombosis  heart  attack and ultimate death. The main  factor causing atherosclerosis  is high blood   concentration  of cholesterol due to increased intake of saturated fat in diet. Diabetes  mellitus, hypothyroidism, smoking  and male sex hormones promote   atherosclerosis. Most  important  preventive  measure is to stop  smoking  and to eat a low  fat diet  containing unsaturated  fats (vanaspati) with  low  cholesterol  content and margarine ( a butter  substitute made  from  vegetable  fats.)