Quote:
Originally Posted by Liz53
Huh? I've done a lot of reading and have never read that - I could easily have missed something. Do you have a source for that?
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http://eatingacademy.com/weight-los...ons-of-fat-flux
Note the "Insulin-" in red causing the TAG -> fatty acids to break down and enter the blood stream.
Edit to add Attia's explanation:
Insulin does the following:
1 Upregulates lipoprotein lipase (LPL), an enzyme that breaks down TAG so they can be transported across cell membranes. Since TAG are too big to bring across cell membranes, they need to be “hydrolyzed” first into free fatty acids, then re-assembled (re-esterified) back into TAG.
2 Translocates GLUT4 transporters to the plasma membrane from endosomes within the cell. In other words, insulin moves the GLUT4 transporter to the cell surface to bring glucose into the cell.
3 Facilitates lipogenesis, that is, facilitates the conversion of glucose into acetyl CoA which gets assembled into fatty acids along with glycerol.
4 Facilitates esterification, that is, facilitates the process of assembling fatty acids into TAG (3 fatty acids per TAG).
5 Inhibits hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL), two important enzymes that breaks down TAG into fatty acids and glycerol such that the fatty acids can be released from the fat cell. Once bound to albumin the free fatty acids are free to travel elsewhere in the body for use (e.g., to the liver for conversion to ketones, to the heart muscle or skeletal muscles for conversion to ATP).
6 Though not shown in this figure, insulin appears to indirectly act on malonyl-CoA, a potent inhibitor of CPT I, one of the most important mitochondrial enzymes that facilitates the oxidation of fatty acids. (CPT I is what enables fatty acids to be shuttled into the mitochondria for oxidation, the process which releases or liberates their energy through electron transport.)