What happens to adipose (body fat) when animals “use it for energy”?



Does it move into the digestive tract, and then they pass it? Is it a separate mechanism? Where does it go and how does it get out?

In: Biology

Except for some water, very few things pass from the body into the digestive tract–it’s usually the other way around.

Body fat molecules get released into the bloodstream, where they’re collected by the liver and processed into other chemicals that circulate in the bloodstream until cells pick them up. Waste products, like CO2, eventually get exhaled. Some waste products–and I’m not sure if fat metabolism produces any of these–get excreted through the urine.

It gets broken down metabolically and eventually excreted from the body as CO2, urine and feces. There’s probably 100s of interrelated mechanisms. It’s extremely complicated.

Fat cells store energy in the form of molecules called triglycerides. Triglycerides are 3 (hence ‘tri’) fatty acid molecules connected together by a glycerol molecule. To use triglyceride as energy, the fatty acids need to be cut from triglycerides and released into the blood stream. Once they are in the blood stream, fatty acids can be picked up by whatever cell in the body needs energy and converted into the energy molecule called ATP by a process called fatty acid oxidation.