Americans are bombarded with a countless variety of nutrition programs promising to whittle waistlines and improve overall health. A low glycemic index diet is one such strategy. By combating blood sugar spikes, this eating plan is believed to curb chronic conditions ranging from diabetes to high blood pressure. In spite of its proposed health effects, the science behind the diet remains unclear and controversial.
The Glycemic Index
The glycemic index, or GI, is a tool used to regulate blood sugar and thereby aid in diabetes management and weight control. Carbohydrate-containing foods are ranked on a scale of 0 to 100 based on their impact on blood glucose. High GI foods, scored 70 and above, include rice, white bread and skinless potatoes. Low GI foods with a score of 55 and below include raw carrots, apples, skim milk and beans. Low GI foods are preferred based on their ability to curb hunger and maintain stable blood sugar levels.
GI Scores and Food Quality
Nutritional quality is not a factor in the GI ranking of foods. Some low GI foods, such as potato chips and ice cream, are heavy in calories, sugar and saturated fat. In contrast, healthier options, such as watermelon, wear a high-GI label. Choosing numerous unhealthy low GI foods may derail your quest for better health.
Confounding Factors
The glycemic index is complicated by numerous factors such as a food's ripeness and preparation method. The more ripe or processed a food, the higher the GI, claims the American Diabetes Association. For example, mashed potatoes carry a higher GI than a baked potato. Prolonged cooking increases GI. Ambiguity is another issue making GI determination difficult. Most foods don't indicate their GI score on the label, and many products go unlisted even in online databases and publications.
The Big Picture
Carbohydrate-containing foods are rarely eaten in isolation. Other nutrients in a meal affect carbohydrate metabolism. Combining a high GI food with a low GI food, protein or fat source will blunt blood sugar elevations. Portion size also comes into play. A heaping bowl of pasta will clearly have a greater impact on your blood sugar and calorie intake than a small half-cup serving. The American Diabetes Association states that the total amount of carbohydrates, rather than the GI, holds the greatest influence on blood glucose.
GI and Weight Loss
Carbohydrates are central to the low GI eating plan. Little attention is given to fat intake, calories or portion sizes. According to the Mayo Clinic, evidence supporting the GI diet as a weight loss tool remains uncertain. Fiber and protein consumption along with portion control may be the cause of weight reduction rather than GI itself. The golden rule of weight loss remains the same: Calories out must exceed calories in.
Bottom Line
The glycemic index is one of many methods to manage blood sugar. Though it has not been associated with specific health risks, the diet is no guarantee for a slimmer figure or diabetes prevention. However, when combined with sensible eating habits and regular exercise, a low GI diet may help keep blood sugar in check.
