Most nutrition experts today support a diet high in carbohydrates (55-60% of total calories), low in fat (<30% of total calories) and moderate in protein (10-15% of total calories). However, other dietary ratios have made headlines in recent years. In particular, enthusiasm has been growing for a diet in which carbohydrates are virtually eliminated while fat and protein are increased. Is it time for you to cut back on your carbs and boost your protein and fat?

Not so fast, says Debra Wein, MS, RD, nutritionist and exercise physiologist at the University of Massachusetts at Boston. Don’t pass the pasta and say good-bye to bagels just yet. We know from decades of research that a diet rich in carbohydrate foods such as whole grains, vegetables and fruits helps to prevent disease, maintain healthy body weight and optimize athletic performance. There is no substantial evidence to support a change in that recommendation.

Some of the carb-bashing theories have focused on the glycemic index (GI), a system for classifying foods based on their effect on blood sugar level. For example, the GI rating for pure sugar is 100 because it is absorbed very quickly and causes a rapid rise in blood sugar. At the other end of the scale, lentils, peanuts and fructose (the natural sugar found in fruit) rate a score of 30 or lower because they are absorbed more slowly and create only a modest rise in blood sugar. Low-fat or nonfat, processed foods such as cookies and cakes, have a high GI due to the abundance of simple sugars added for taste when fat is removed. High-fiber foods, such as whole-grain bread, have a lower GI.

Many nutrition experts believe the GI itself has limited practical value since most people consume a variety of foods together in meals. However, the underlying concept -- that all carbohydrates are not equal -- is an important one. We do need to be concerned about the quality of the carbohydrates we eat, says Wein. Complex carbs from whole grains, vegetables and fruits not only provide fiber to keep the digestive tract running smoothly but also supply a better balance of vitamins and minerals than highly refined simple sugars. Heavily processed foods with a lot of refined sugars can have a negative impact on your blood sugar level, your mood and your ability to stop eating. You can find yourself caught in a vicious circle of carbohydrate consumption that ultimately leads to unhealthy weight gain, Wein says.

Scientists believe the types of carbs found in convenience foods can dangerously raise triglycerides and lower HDL (good) cholesterol, particularly in people who are insulin resistant, as many diabetics are. In short, you are safer with whole foods, such as grains, fruits and vegetables. If you can’t buy fresh products, frozen is better than canned because the freezing process locks in freshness and maintains vitamin and mineral content.

How can you make sure you get enough of the right kinds of carbohydrates in your diet? Here are some tips to expand your food choices and optimize the nutritional value of the carbs in your diet: