With so many different low-carbohydrate diets to choose from, it would be easy to think that fewer carbohydrates are the key to weight loss. The truth is there are three main types of carbohydrates -- sugar, starch and fiber. For optimum health, sugar should be restricted, starch should be limited and fiber consumption should be encouraged. High-fiber, nutrient-dense carbohydrates such as vegetables, legumes, fruit and whole grains provide essential vitamins, while sugar often provides extra calories with little nutritional value.
How Many Carbs?
The University of Maryland Medical Center says that you need between 100 and 150 g of carbs daily to ensure proper nutrition. Since each gram of carbohydrate has 4 calories, that's between 400 and 600 calories; if you're eating between 1,200 and 1,800 total calories a day, assume about 30 percent come from carbs. This is considered a low-carb diet, as the 2010 USDA Dietary Guidelines suggest that between 45 and 65 percent of your calories should come from carbohydrates.
Natural Sugar Vs. Added Sugar
Sugar is a type of carbohydrate -- and the one that has the most impact on blood sugar and insulin production. Low-carb diets restrict sugar intake to stabilize glucose, reduce hunger cravings and encourage your body to burn stored fat for energy. Your diet should make the distinction between natural sugars -- found in fruit and dairy products and added sugars -- refined sugar, honey, syrups added to sweeten foods and beverages. Added sugars should be avoided as much as possible. You may need to limit natural sugars; eating whole fruit rather than drinking juice, eating fresh fruit instead of dried fruit and eating no more than two servings of low-fat dairy daily will ensure adequate nutrition without raising glucose levels too quickly.
Starch and Fiber
Choosing the right carbs will help you feel full, consume fewer overall calories and lead to weight loss. Fiber slows digestion and can increase satiety. Because fiber is indigestible, it contributes a negligible amount of calories to your diet while adding bulk -- you'll feel full faster and eat less. On the other hand, starch is easily converted to glucose and will raise blood sugar levels quickly. Limit starchy vegetables such as potatoes, corn, parsnips and rutabaga. These foods do contribute nutrients to your diet, but should be eaten sparingly because of their effect on glucose and insulin.
Using the Glycemic Index
The glycemic index, or GI, measures the potential of any carbohydrate to raise your glucose levels. It ranks foods on a scale of 1 to 100 in comparison to pure glucose, which scores 100. Choosing foods lower on the GI will stabilize blood sugar and regulate insulin production. Low-GI foods include most vegetables and fruits, except those high in sugar or starch, legumes and true whole grains such as oatmeal. The GI should be used only as a guide. Fat slows digestion and lowers the GI of some high-sugar foods like chocolate bars. A piece of fruit may score higher than chocolate, but fruit is always the better choice.
References
- Harvard School of Public Health; The Nutrition Source -- Carbohydrates: Good Carbs Guide the Way; 2011
- Glycemic Index: About the Glycemic Index
- Better Health Channel: Sugar
- American Diabetes Association: Carbohydrates
- National Heart Lung and Blood Institute: Limit Fat and Sugar
- University of Maryland Medical Center: Low Carb Diets -- The Right Way to Go?
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