Frank Mikulka's Weekly Fitness Tip
Can Muscles Turn into Fat and What is a Glycemic Index?
November 7, 2006

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This question might sound stupid, but is it true that muscles turn to fat when you don’t work them? Also, what is the glycemic index you hear so much about? (Andrea, Queens)

Muscle will no more turn to fat than fat will turn into muscle. Both are distinctly different tissues with specific functions. Long muscle fibers will never turn into spherical blobs of fat.

Muscles are composed of long strand-like fibers with contractile proteins designed to exert force. Fat cells are round receptacles designed to store fat. Training increases the size of muscle fibers, hypertrophy. Detraining or no training reduces the size of muscles, atrophy. Excess caloric consumption causes fat cells to grow in size as they store more fat. Fat cells shrink when you burn more calories than you eat. Here’s part two of your question:

The Glycemic Index is the rate of carbohydrate digestion and its effect on the rise of blood/glucose levels. Foods that digest rapidly and cause a pronounced rise in blood sugar have a high glycemic index. Those digested and absorbed more slowly because of fiber or fat have a low index. High glycemic index foods - sugar, white bread, refined cereals and white potatoes.

Low index foods – beans, lentils, fruits like apples and grapefruits.

Medium index foods – pasta, whole grain breads, brown rice, oatmeal and bran.

Listen to Frank Mikulka's Weekly Fitness Tips every week on Debbie Mandel's Turn On Your Inner Light Show every Tuesday evening from 7:00 to 7:30 pm on WGBB 1240AM. Also available on