Millions of people who want to lose weight have had success by reducing their carbohydrate intake with well-known diet plans such as the Atkins diet or The South Beach Diet. Others have simply modified their eating patterns by eating fewer carbs in smaller portions.

The theory is that low-carb diets keep blood sugar stable. When we eat foods with carbohydrates — such as breads, pastas, rice or candies — the carbohydrates break down to simple sugars in the body, causing blood sugar to rise. When blood sugar rises, the body produces insulin to bring the sugar level back to normal. When insulin is high, weight gain is more likely because the sugar is taken out of the blood and converted into fat.

The glycemic index is a tool that some low-carb plans use to determine which foods are best to eat. Some foods cause a higher rise in blood sugar than others, even if they contain the same amount of carbohydrate. The higher the glycemic index of a certain food, the higher the sugar level will rise in response to that food.

Some nutrition experts say that low-carb diets work for many people, but they say the reasons have little to do with insulin. These experts believe that people lose weight when they reduce carbohydrates because:

• When you burn fat without carbohydrates, your body creates byproducts called ketones. When ketones build up in your bloodstream, you may not feel as hungry.
• When you limit the variety of foods you can eat, you naturally reduce your overall calorie intake
• When you begin a low-carb diet, your body burns glycogen, the body’s main source of stored energy. Glycogen contains a lot of water, so burning glycogen leads to the release of water and increased urination, causing weight loss.
• When you follow a strict low-carb diet, you eat foods that are higher in fat. Fat takes longer to digest, which makes you feel fuller longer.

Don’t confuse “low-carb” with “low-calorie.” If you’re serious about losing weight, you need to keep both carbohydrates and calories in mind. For instance, a large chicken Caesar salad — minus the croutons — is low-carb, but it can still weigh in at about 1,000 calories with the dressing! Keep calories in mind when dining out, and read the fine print on packaged foods labeled as “low-carb” when shopping for groceries.

When you go to the store, it helps to know the difference between low-glycemic “good” carbohydrates (such as whole-grains, fruits and vegetables) and “bad” carbohydrates (such as foods made with white flour and sugar).

Here’s a handy guide to making the right food choices, based on the glycemic index:

• No-sugar-added sauces and dressings
• Real mayonnaise in small amounts
• Whole-wheat, whole-grain or rye bread
• Oats and high-fiber bran cereals
• Brown rice and whole-wheat pasta
• Lean meat (turkey breast, chicken)
• Fish, especially sardines, mackerel and salmon
• Lean breakfast strips or Canadian bacon
• Eggs
• Avocado
• Nuts, especially walnuts, Brazils, pecans and almonds
• Seeds, especially pumpkin, sesame and sunflower
• Beans and lentils
• Fresh or frozen vegetables
• Fresh fruit, especially berries, apples, kiwifruit
• Flax seed and olive oil

• Fat-free foods such as mayonnaise, salad dressings, cream cheese, etc.
• Sauces or salsa where sugar is one of the main ingredients
• Jams, jellies and syrups
• Sugar-coated cereals
• Pancakes, bagels, muffins and waffles
• White bread, rolls or crackers
• White rice and pasta
• Chips, pretzels, popcorn
• Regular sodas
• Alcohol

Following a low-carb meal plan means eliminating foods that are high on the glycemic index — such as alcohol, refined sugar and white flour–based carbohydrates — and replacing them with carbs that are low on the glycemic index, such as whole grains.