Lipoprotein Lipase Important for Fat Burning

Lipoprotein lipase important for fat burningJanuary 7th, 2010 – Lipoprotein lipase (LPL) is an enzyme that breaks apart fat (triglycerides) into their fatty acid components for transport and use inside cells.

An increase in lipoprotein lipase activity means an increase in the flow of fatty acids into the cell.  An increase in LPL activity in muscle cells means they will use more fat and less sugar for energy, which is a good thing if you are trying to stay lean.  An increase in LPL activity in fat cells, however, will mean increased fat stores.  There are many factors involved in the regulation of LPL activity, but two big contributors are the hormones insulin and testosterone.

Insulin increases LPL activity in fat cells, while decreasing LPL activity in muscle cells.  (1) Anything that drives up insulin (mainly dietary carbohydrates) will increase the flow of fatty acids into fat cells for storage and cause muscle cells to burn sugar instead of fat.

Testosterone also has a regulatory effect on LPL activity in muscle. Lipoprotein lipase activity in the fat cells of the abdominal region is greater in men than in women, and reduced testosterone levels only increases activity.  Keeping testosterone levels high, however, works to reduce LPL activity in the male abdominal fat cells thus discouraging fat storage in this area. (2)

References –

1. Lipoprotein lipase regulation by insulin and glucocorticoid in subcutaneous and omental adipose tissues of obese women and men.

Fried SK, Russell CD, Grauso NL, Brolin RE.

J Clin Invest. 1993 Nov;92(5):2191-8

2. Good Calories Bad Calories

Gary Taubes

Alfred A Knopf 2007 Pages 397-399

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Triglycerides: High Glycerol Phosphate Makes You Store Fat

Triglycerides

December 8th, 2009 – We’ve all heard that carbs make you fat.  When we eat carbohydrates our bodies release insulin, a storage hormone that takes the sugars entering the blood stream and stuffs them into our cells.  What you may not have heard, however, is that on top of insulin, carbs have a unique ability to increase blood triglyceride levels and make us store it as fat.  This ability comes in the form of a simple molecule called glycerol phosphate.

The fat stored in our fat cells is made up of triglycerides.  Triglycerides are composed of three (tri) fatty acids bound to a single glycerol molecule. Glycerol phosphate is a key component in the process of binding free fatty acids together to form triglycerides, as it provides the glycerol backbone that the fatty acids bind to.

Glycerol phosphate is a byproduct of carbohydrate metabolism (by glycolysis).  The more glucose broken down for energy, the more glycerol phosphate we have available, and the more free fatty acids can be bound together to form triglycerides and stored as fat.  In fact, the rate at which the body assembles fatty acids into triglycerides largely depends on the availability of glycerol phosphate.  (1)

References –


1. Good Calories Bad Calories

Gary Taubes

Alfred A Knopf 2007 Pages 388-389

Carbohydrates Drive Up Cholesterol

Evil ToastOctober 16th, 2009 – Despite what your doctor and favorite fitness magazine tell you, dietary cholesterol is not the enemy. In fact, our own cells manufacture roughly 80% of the cholesterol in our body (1). Increase your dietary intake, and normally the body will compensate by producing less of its own. Decrease, and your body will make more.

So where do carbohydrates fit in to all of this?

When you ingest carbohydrates, they are broken down into glucose and released into the blood stream. This raises blood sugar levels, and the body releases insulin to deliver the sugar to the various cells in the body for use as fuel. Aside from storing nutrients in the body, insulin also stimulates the enzyme HMG-CoA reductase, which determines the rate and amount of cholesterol produced by our cells. (2) The more cholesterol our cells produce, the less they remove from the LDL particles in the blood, and the more cholesterol remains in circulation.

Take home message – It’s the toast, not the eggs.

References

1. Protein Power
Dr. Michael Eades
New York, NY: Creative Paradox LLC (2000)

2. Interaction between cholesterol and glucose metabolism during dietarycarbohydrate modification in subjects with the metabolic syndrome
Maarit Hallikainen, et al.
Am. J. Clinical Nutrition, Dec 2006; 84: 1385 – 1392.

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