The Glycemic Index

Not all carbohydrate foods are created equal – in fact they behave quite differently in our bodies.  The glycemic index (GI) describes this difference by ranking carbohydrates according to their effect on our blood glucose levels.  Choosing low GI carbs – the ones that produce only small fluctuations in our blood glucose and insulin levels – is one secret to long-term health, reducing your risk of heart disease and diabetes, and is a key to sustainable weight loss.

The GI is a ranking of carbohydrates (carbs) on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating. Foods with a high GI are those which are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels.  Low-GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood sugar and insulin levels, and have proven benefits for health.

Low GI diets have been shown to improve both glucose and lipid levels in people with diabetes (type 1 and type 2). They have benefits for weight control because they help control appetite and delay hunger.  Low GI diets also reduce insulin levels and insulin resistance.

To determine a food’s GI rating, measured portions of the food containing 10 – 50 grams of carbohydrate are fed to 10 healthy people after an overnight fast.  Finger-prick blood samples are taken at 15-30 minute intervals over the next two hours.  These blood samples are used to construct a blood sugar response curve for the two hour period.  These blood sugar curves are compared to the curve for sugar and ranked in proportion.

The use of a standard food is essential for reducing the confounding influence of differences in the physical characteristics of the subjects. The average of the GI ratings from all ten subjects is published as the GI of that food.

Eating a lot of high GI foods can be detrimental to your health because it pushes your body to extremes.  This is especially true if you are overweight and sedentary.  Switching to eating mainly low GI carbs that slowly trickle glucose into your blood stream keeps your energy levels balanced and means you will feel fuller for longer between meals.

Low GI diets:

  • help people lose and control weight
  • increase the body’s sensitivity to insulin
  • improve diabetes control
  • reduce the risk of heart disease
  • reduce blood cholesterol levels
  • can help you manage the symptoms of PCOS
  • reduce hunger and keep you fuller for longer
  • prolong physical endurance

High GI carbs help re-fuel carbohydrate stores during and after exercise which is a very specific need that justifies high GI carbs.  During intense exercise, and for a few hours afterward, high GI foods can be beneficial by spiking insulin during this time.  Insulin is normally a fat storage hormone, but during and after exercise it switches to a protein building hormone.

The basic technique for eating the low GI way is simply a “this for that” approach – that is, swapping high GI carbs for low GI carbs.  You don’t need to count numbers or do any sort of mental arithmetic to make sure you are eating a healthy, low GI diet.

  • Use breakfast cereals based on oats, barley and bran
  • Use breads or pastas with whole-grains or stone-ground flour
  • Reduce the amount of potatoes, corn, beets, and carrots you eat
  • Reduce really sweet fruits e.g. pineapple, orange, mango
  • Enjoy all other types of fruit and vegetables
  • Use Brown Basmati or Doongara rice
  • Eat plenty of salad vegetables with a vinaigrette dressing

Be sure to include protein with every meal to help blunt insulin response.  The Paleo, Mediterranean, Ornish, and South Beach Diets are several examples of a low glycemic diet.

Author

Scott Rollins, MD, is Board Certified with the American Board of Family Practice and the American Board of Anti-Aging and Regenerative Medicine.  He specializes in Bioidentical Hormone Replacement for men and women, thyroid and adrenal disorders, fibromyalgia, weight loss and other complex medical conditions.  He is founder and medical director of the Integrative Medicine Center of Western Colorado (www.imcwc.com) and Bellezza Laser Aesthetics (www.bellezzalaser.com).  Call 245-6911 for an appointment or more information.

 

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