Question

Explain how insulin and glucagon regulate lipolysis

Answer 1

The fat stores in your body are metabolically active and dynamic tissues.Two opposing forces determine the amount of fat you carry around from day to day.Lipogenesis is the process that converts sugars to fats,which are subsequently deposited and stored in fat tissue.Lipolysis is the process of fat breakdown,typically to generate energy.These two metabolic activities are controlled by hormones secreted by your pancrease,pitutary and adrenal glands,and ovaries and testes.The pancreatic hormone insulin is particularly important in fat metabolism and lipolysis.

Insulin is secreted from pancreatic cell in response to rising levels of glucose in the bloodstream.The consumption of food-particularly proteins and carbohydrates prompts the release of insulin from pancreas.In contrast,fasting and a falling blood sugar reduce insulin production and release.Insulin triggers the absorption of glucose by muscle,liver and fat cells,thereby lowering the blood sugar level.

When energy needs to increase or blood sugar level falls,the production of hormones that mobilize the energy stores begins to rise.These hormones-such as Glucagon and adrenalin-stimlulate lipolysis,which involves the breakdown of triglycerides stored in fat tissue.The fatty acids and glycerol molecules liberated by lipolysis are then metabolized to generate energy.The hormones that oppose insulin and stimulate lipolysis are called glucose counter-regulatory hormones.

The horones that control lipolysis and lipogenesis do more than simply antagonize each other's action in fat tissue.Hormones that promote lipogenesis may actually interfere with the production or secretion of other hormones that stimulate lipolysis.For example:when blood sugar level rises,insulin does not simply drive glucose into cells.It also inhibits the secretion of the counter regulatory pancreatic hormone glucagon.In this way,insulin promotes lipogenesis and effectively prevents lipolysis.

Insulin inhibits lipolysis and slows the breakdown of adipose tissue.This has important implications if you have type 2 diabetes or prediabetes.With these conditions,the body resists the action of insulin.The pancrease tries to compensate by producing excessive amounts of insulin-which promotes fat storge.The interplay among the various factors that contribute to lipolysis is complex and insulin is only one of those factors.