Question

Apparently, humans can deplete all or most of their TAGs reserves without major harm to their health. What do you think happens after those stores are completely depleted?

Answer 1

Triacylglycerols [TAGs] are broken down by lipases . Pancreatic lipases in the intestinal lumen help to absorb fatty acids from the diet into the intestine.Lipoprotein lipases in the capillary walls help absorb fatty acids from chylomicrons and VLDLs into target tissues.

Hormone sensitive lipases inside cells break down fat stores in the adipose tissue.

Once absorbed into the blood, lipoprotein lipases hydrolyse TAGs into fatty acids and glycerols. In muscles, fatty acids are oxidised for energy. In adipose tissues, they are re-esterised as TAGs for storage .

When the stored TAGs are completely depleted, they are replenished from the excess carbohydrates stored in the liver cells.

Products of carbohydrate and amino acid catabolism are directed towards fatty acid synthesis. When stored TAGs are depleted ,they an again be synthesised from carbohydrates stored in liver cells .