October 19, 2006
Low-crab products still can be found on grocery store shelves and in restaurant menus, though the buzz over low-carb diets has already subsided. But can these foods be included into a healthy diet, assure safe and permanent weight loss?
Here is an interview with a preventive medicine and nutrition specialist at Mayo Clinic, Donald Hensrud, M.D., where he answers common questions regarding carbohydrates, low-carb diets and the role of carbohydrates in our life.
Are the food products, claimed to be low carb, healthier?
Legally the term "low carb" is not defined. Even the Food and Drug Administration (FDA), responsible for claims on food labels in the United States, has no definition of low carb products.
In fact, low carb, as well as similar claims "carb fit" or "carb wise", are marketing terms. They've been created by manufacturers to sell food products. Customers believe low carb foods to be healthier, but it is not always so. Low carb cookies and cakes have high fatness and calories indexes, and the low carb label doesn't make them healthier. For instance, one low-carb nutrition bar can have up to 240 calories, 6 grams saturated fat and 12 grams of total fat.
Does low-crab food overeating have any downside?
High in fat and calories low-carb food products can cause digestive symptoms. During the manufacturing process of low carb products (low-carb candy bars, for example) some sugar alcohols, such as the sweeteners sorbitol or maltitol, are used to replace carbohydrates. These substances consumed in large quantities may cause digestive discomfort like diarrhea or cramping.
There are terms total carbs and net carbs. What's the difference between them?
According to FDA calculations, "total carbs" is a subtraction of the amount of fat, protein, water and ash from the total weight of the food. (Ash is a scientific term for the nonburnable part of a food including minerals like phosphates and calcium) This number is listed on the food label.
FDA doesn't approve or define the term "net carbs". It represents the number of carbohydrates without glycerin, fiber, and sugar alcohols. Proponents of low-carb diets use the net carbs term to show a reduced amount of carbohydrates on their products. According to their theory glycerin, fiber, and sugar alcohols, which are all forms of carbohydrates, do not make any contribution to the rise of blood sugar, and therefore they shouldn't be taken into account when evaluating carbs. In reality glycerin and sugar alcohols do rise (raise) blood sugar and contribute calories.
How can you specify good carbs and bad carbs?
Historically the notion that there's no bad food has been supported by the majority of nutritionists and dietitians. It claimed that everything can be eaten in moderation. But there are foods, sugar for example, that have no nutritional value besides calories. Therefore to the group of "bad" carbs we should refer foods, which are no reason to consumer, apart calories. On the other part, whole grains provide many minerals, vitamins, fiber, and other substances that promote health. This puts whole-wheat pasta, brown rice or oatmeal and other grains in the "good" carb category.
Anyway it is important to control the amount of food consumption and keep your proportions in check. Too much of any food can cause excess calories that will subsequently lead to weight gain.
What's the theory behind low-carb diets?
The theory states that carbohydrates cause the rise of blood sugar levels, which t further kicks in insulin. Blood sugar, brought to the cells by insulin, prevent fat breakdown in the body. It means there is no way for you to burn excess fat and lose weight. Proponents of low-carb diets make their conclusion based on this theory. They expect the weight loss to be connected with blood sugar and the insulin level, which are related to the amount of consumed carbohydrates. So if you are not eating carbs, your body provides needed energy breaking down fat. Some people on low-carb diets do lose weight, but their weight loss is more likely due to the eating fewer total calories, whether they're from carbohydrate, fat or protein. There is no evidence that the weight loss and the blood sugar and insulin levels are related.
But low-carb diets work. Why does it happen?
Here are four factors low-carb diets contribution to weight loss:
Loss of water weight.
Decreasing the carbohydrate consumption you burn glycogen, which contains large amounts of water. Therefore weight loss is caused by the release of water and increased urination, the consequences of burning glycogen.
Burning fat without carbohydrates you may not feel as hungry, because of the byproducts called ketones. They are created during this process and build up in your bloodstream.
Increased feeling of fullness.
Low-carb diets usually have higher fatness indexes. It is known that fat takes longer to digest, so feel fuller longer.
Choosing a low-carb diet you strictly limit the variety of foods allowed for consumption. In this way you reduce your overall calorie intake. Bread, rice, pasta, milk, cereals, most fruit and any sweets - the products reach in carbohydrates. They usually provide over half of people's daily calories. But on a low-carb diet carbohydrates are limited or avoided, what leads to a significant diminution in calorie intake.
Can certain combinations of foods - for instance high-fat, high-protein foods with carbohydrates - lead to weight loss faster?
It doesn't matter how the calories are consumed, so there's nothing special about certain foods or combinations of foods.
Do low-carb diets have any long-term health risks?
It is still not known whether low-carb diets have the long-term health effects. However there were a few studies that looked at the benefits and risks, but none has been conducted over a long enough period to see the consequences of the diets: significant changes of health conditions that develop over many years, such as cancer, heart disease, and kidney or bone problems.
Do you have to stay on this diet for term of life?
Theoretically, if you do lose weight, you need to stay on the program to maintain weight loss. But it appears that the low-carb diet is not easy to maintain for a long time as any other diet. The comparison of the results of low-carb diets and low-fat diets reveals that after a year, people dropped out of both diets at similar rates. This proves the low-carb diet to be no easier to stick to long term.
Is there a need to distinguish between various types and amounts of carbohydrates, if you're at a healthy weight?
Yes - but regardless terms of net carbs and total carbs. You should make wise food choices looking at the health effects of products you consume. Whole grains, fruits and many other carbohydrate-containing foods are loaded with essential minerals, vitamins, fiber and other substances that promote health. They form the basis of a healthy diet, as well as other plant-based foods, including legumes, vegetables, seeds and nuts. The key to a healthy diet lies in the proper control of variety and portion of foods. While exclusion or severe limit of consumption specific food group (such as carbohydrates or fat) won't lead to the long-term health.