Let's say you eat a very unhealthy snack that contains 90% sugar and 10% fat. Would somatic cells not start using the fat for energy until all the sugar is used up?
Does the body not use fat at all if there is more bio-available sugar to be used? Or is there always a proportion of fat being used for energy?
In a very simplified explanation - the body usually picks the process which is easiest/ fastest which would be to absorb the glucose then the fat would be used for energy as this takes longer to digest and absorb because it is a relatively complex molecule which also requires bile to emulsify it.
Starchy/ high glucose products will already be broken down in the mouth by amylase and absorbed in the intestine + pancreatic amylase etc. which takes around 20 mins-1hr whereas soluble fats are digested primarily in the small intestine (by enzyme lipase) for (very approx.) 1-4 hours depending on the amount ingested. Insoluble fats are broken down into soluble fatty acids and glycerol which can be absorbed into the blood.
The amount of either you use for energy just depends on how much energy you expend.
