low GI (best):
whole-grain breads and pastas
bran cereals
soybeans
baked beans
peaches
apples (and apple juice)
oranges
milk
yogurt
chocolate
moderate GI:
sourdough or rye bread
shredded wheat
bananas
pineapple
orange juice
ice cream
high GI:
white breads and pastas
white or short-grain rice
waffles
potatoes
jelly beans
soft drinks
honey
Author: J. Lee Miller
Glycemic Index (GI) is a measure of how quickly glucose is absorbed into the bloodstream after a person eats a certain food, how high blood glucose rises, and how quickly it returns to a normal level. A low GI - slow absorption, a modest rise in blood glucose, and a smooth return to normal - is desirable. A high GI - fast absorption, a surge in blood glucose, and an overreaction that plunges glucose below normal levels - is undesirable. A food's effect on blood glucose depends on several different factors working together, and the effect is sometimes surprising. For example, ice cream is high in sugar, but it produces less of a response than potatoes (a high-starch food). However, potatoes (and other foods with a high GI) produce a significantly different response in blood glucose when eaten as part of a balanced meal. A low-glycemic diet improves one's metabolism, and it may also help prevent heart disease, diabetes, and obesity. Fibers and other slowly-digested carbohydrates prolong the presence of foods in the digestive tract, providing greater satiety and lowering the GI, which can help with weight control. A high-glycemic diet seems to lead to overeating in overweight people. Instead of selecting carbohydrates based on quality, some people are reducing their carbohydrate quantity by adopting a low-carbohydrate diet rather than a low-glycemic one.
Those who promote high-protein, low-carbohydrate diet plans claim that carbohydrates are bad for you. Some even say that carbohydrates are as bad as toxic poisons or addictive drugs. "Starches and sugars are considered evil because they are absorbed quickly, and they produce a rapid rise in blood glucose."1 The pancreas then responds by secreting more insulin (a fat-storage hormone) and less glucagon (a fat-release hormone). "Insulin is touted as the real villain responsible for our nation's epidemic of obesity."1 True, insulin facilitates the transport of glucose into the cells and the storage of fat. However, insulin is only one of many factors involved in metabolism and weight control. Also, insulin does not always respond to foods as one might expect. For example, whole-grain pasta (a high-carbohydrate food) produces less of an insulin response than beef (a high-protein food). Many carbohydrates (whole-grains, fruits, vegetables, and legumes) are high in fiber, which slows glucose absorption and moderates insulin response. Insulin causes problems only when the body develops insulin resistance - when the cells do not respond to the large quantities of insulin that the pancreas continues to pump out in an effort to get a response. Insulin resistance is not caused by carbohydrates, proteins, or fats; rather, it accompanies being overweight or obese. With weight loss comes an improvement in insulin response.
nausea
fatigue (especially when physically active)
constipation
low blood pressure
elevated uric acid (which can exacerbate kidney disease and cause inflammation of the joints in those predisposed to gout)
stale, foul taste in the mouth (bad breath)
in pregnant women, fetal harm and stillbirth
One of the attractions of high-protein, low-carbohydrate diet plans is the eliminated need to count calories. The design of these plans ensures a low caloric intake (800 to 1200 calories per day) because food intake is so limited. Weight loss occurs because of this low energy intake - not the ratio of carbohydrates, proteins, and fats. "Success, then, depends on the restricted intake, not on protein's magical powers or carbohydrates' evil forces."1 Any diet in which intake is restricted can result in weight loss. High-protein, low-carbohydrate diets offer short-term success for some people, but they fail to produce long-term results for most people. A healthy diet will maintain weight loss and support good health over the long term. High-protein, low-carbohydrate diets do not support optimal health over time.
High-protein, low-carbohydrate diet plans often focus so much on increasing protein and cutting carbohydrates that the fat content of many high-protein foods is ignored. Let's say Sallie eats bacon and eggs for breakfast, a ham and cheese sandwich for lunch, and a dinner of barbecued ribs. Sallie would consume not only 100 grams of protein, but also 121 grams of fat! As if that wasn't enough, Sallie's meals for the day, along with a snack of peanuts, would only provide her with 1600 calories. High-protein, low-carbohydrate diets are too often extremely high in fat, saturated fat, and cholesterol - all of which are dietary risk factors for heart disease.
Cutting out or cutting down on fruits, vegetables, and whole-grains means missing out on fiber, vitamins, minerals, antioxidants, and phytochemicals, all of which protect against disease. Some people on high-protein, low-carbohydrate diets take supplements to account for these nutrient deficiencies. However, foods provide many more health benefits than any supplement can provide. Notice that they are called supplements, not replacements; if a diet is inadequate, it needs to be improved rather than supplemented.
A high-protein, low-carbohydrate diet puts the body in a state similar to that of fasting. When there are too few carbohydrates being consumed, the body uses its glycogen (the stored form of glucose) stores to provide glucose for the cells of the brain, central nervous system, and blood. Once these glycogen stores are depleted, the body turns to its remaining source of glucose - protein. A high-protein, low-carbohydrate diet may provide plenty of protein, but the body will still use some protein from body tissues - resulting in a loss of lean body mass, or muscle.
A dieter on a high-protein, low-carbohydrate diet can experience significant weight loss. However, much of the weight lost is not only fat, but also glycogen, protein, body fluids, and important minerals. The good news is, once the dieter returns to a well-balanced diet, the body will quickly regain these necessary nutrients.
1 Understanding Nutrition, 9th ed.
