Fatty acids are the main source of energy for
Fed state Preferred fuel
Starvation preferred fuel




RBC


Glucose
Glucose




Heart


Fatty acids
Ketone bodies




Brain


Glucose
Ketone bodies




Liver


Glucose
Fatty acids / protein




Muscle


Glucose
Fatty acids




Adipose tissue


Glucose 
Fatty acids.
Muscles
Heart
Liver
RBC