H Lecture 2

H Lecture 2 - NST 160 Lecture 2 Epidemic of Obesity: Health...

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NST 160 Lecture 2 Epidemic of Obesity: Health Consequences, Fitness/Fatness Issue and Therapeutic Strategies Diseases Associated with Overweight/ Obesity: Underlying Mechanisms? Is All Body Fat the Same? -It is probably not. There are different aspects of fat most particularly where the fat is located, is the fat under your skin, or is it in your viscera, inside your body within the organs or in the organs. How big are the fat cells? Small or large? 1) Fat location: --there are people who have central obesity = big belly --there are people who have peripheral obesity = gluteo-femoral obesity (big body, big legs, fat in the extremities) --The central obesity, android obesity, has a far higher number of risk factors for diseases like diabetes, hypertension, heart disease… --Why would central obesity be worse than peripheral obesity? -One idea that emerged is that the anatomical location among other things influences two aspects of body fat: a. Lipolysis -this is the breakdown of triglycerides to fatty acids -major component of fat cell: triacylglycerides—this is 20-40% of our whole body -fat cell’s main function is to store fat or release fat; it is our energy reserve -the amount of energy in fat is well over a hundred thousand calories (the amount of energy from carbohydrates is about 3000-5000 calories; the amount of energy from protein is hopefully close to zero because you wouldn’t wanna be using protein for energy, we use protein for other things in our body) -fat is our energy store; it is very efficient that way -the problem is, it has adverse effects when it is in excess -when the adipose is in your organs, visceral (inside), it’s very close to the liver, it might release Fatty Acids when hydrolyzed and the FA will go to the portal vein which gravitates into the systemic circulation [obese people when opened up, has unbelievable amount of fat surrounding everything, you can barely even see their tissues and that kind of fat is thought to be very deleterious] -another possibility is that visceral fat has a different biology; it is much more lipolytic (the reverse process is TAG synthesis) so the balance of lipolysis and synthesis is what determines how much fat you have in an organ; you could have a tissue which has a lot of fat but constantly breaking it down and re- esterifying it -visceral fat is more active metabolically -why is it bad to be more active metabolically? It is counterinuitive because you would think that it would be better right? But! The worst thing you can have is your fatty acids in the circulation and in your tissues, like your liver and muscle. -it is better to have your fat tucked away in a fat cell than to have it released to cause trouble everywhere else -if a certain type of fat cell like a visceral central fat cell, releases its fatty acids more easily, then they go out to the tissues and cause trouble… even if they come back in, they are spending more time out causing trouble metabolically 2) Cell size and number -another kind of fat distinction which could be more lipolytic is big fat cells
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H Lecture 2 - NST 160 Lecture 2 Epidemic of Obesity: Health...

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