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By Melissa Tennen, HealthAtoZ writer
Low-carb chocolate. Low-carb ice cream. Low-carb bread. They are invading grocery stores. Do they help you lose weight? Should you try them? Here to talk about the issue is Cindy Moore, R.D., director of nutrition therapy at the Cleveland Clinic Foundation.
What are low-carb diets?
Cindy Moore: Actually, we are talking about low-carb diets that are in a variety of ranges for carbohydrates. There is not one standard definition for a low-carb diet. One diet has 5 to 8 percent of calories from carbs. That's a very substantial reduction in calories irrespective of people's weight or size. Another diet has 40 percent carbs.
Let's say you are on a 2,000-calorie-a-day diet. If you were going by 40 percent carbs, you would be eating 200 grams of carbohydrates a day. The government, the American Dietetic Association and the American Heart Association say what you really should be getting is 55 to 60 percent of your calories from carbohydrates. That would be about 275 carbohydrates. Two thousand is an arbitrary number. If you are obese and need to lose weight, you might need to consume fewer calories - 1,800, for example. But your carbohydrate intake should be 55 percent of those total calories, which would be 240 grams of carbohydrates.
Why are people losing weight on low-carb diets?
Moore: If you are following these diets compared to any other diet, there is not significant difference. Someone on a low-carb, high-protein diet may be able to get the weight off in the short-term, but it doesn't work any better than any other diet. Over a longer period of time, such as a year, there is not a significant difference in weight loss seen when you compare traditional approaches to high-protein, low-carbohydrate diets.
Part of the reason for success on these diets is that you limit the types of food you eat. A lot of people who become obese are eating a lot of sweets and pastries. These foods have high carbohydrate content and a lot of calories. The bottom line is that you are eating fewer calories when you remove them from your diet. Part of the effect of any diet is that you are eating fewer calories. Any diet with some restriction is going to cause you to lose weight. Most diets follow a pretty strict plan. But it can be boring and too restrictive, and soon people gravitate to their old eating habits.
What about these products that retailers are marketing that say they are low-carb like chocolate and ice cream? Why are they bad?
Moore: Retailers offer foods that more closely mimic the foods that people couldn't eat while they were on these diets. They have reformulated the food. To the dieter, the manufacturers are saying the forbidden food is now acceptable. "I can eat this and lose weight."
A lot of people on these diets do not realize these foods still contain calories. They think, "They are lower in carbs. So I can eat them and still lose weight." People need to be very aware of the portion size issue. If you compare calories in these low-carb foods to other foods, they are often about the same.
Part of my apprehension is, as more and more of these foods are becoming available, how are dieters going to deal with them? It is definitely going to slow down their weight loss, and they are paying a lot of money for them.
Most people do not strictly follow a diet plan. Millions of copies of these diet books are sold, and many people have not read the books and are not following the stages of the plans. They get the idea from a friend who tried it.
What are the health hazards of low-carb diets?
Moore: So far there don't seem to be any major problems short-term. But we still don't have the science to support that this is safe for the long-term. However, we have a lot of science supporting a diet high in carbs. Diets with whole grain, fruits, vegetables, legumes and low-fat dairy products promote health and prevent disease risk and they are a rich source of carbohydrates. Many of the low-carb diets exclude fruits and vegetables as well as low-fat dairy.
My question is what is this going to do to long-term disease risk? We know there is a link between cancer and low fruit and vegetable intake. Also, osteoporosis is related to the amount of low-fat dairy products and other sources of calcium that you consume. My bigger concern is that obesity rates are rising. Is this going to make the problem worse?
Is there a danger of people thinking it's a license to eat these foods that are reformulated as low-carb even if people aren't following a low-carb diet plan?
Moore: A lot of what is happening is reminiscent of what happened 10 years ago with the low-fat foods. Manufacturers got on the bandwagon because we heard how villainous fat was. All these low-fat and nonfat products came out. People either ate them in unlimited amounts or didn't have consistency of portion size: "This gives me license to binge on something else later." It's like that with carbohydrates now.
No matter what type of plan, you need to make sure you are taking in fewer calories. It's ludicrous to think you can eat fried chicken with abandon and lose weight. You can fit fried chicken into a healthy diet, but you have to watch portion size and frequency. Eating it once a month or even twice a month isn't going to hurt you. But when we talk about the super size meals or the unlimited buffets, people are usually taking in more calories than they need.
These plans seem to be geared toward people who don't exercise, and the plans don't encourage exercise. Why is that?
Moore: It's not a message that people want to hear. The message from The National Institutes of Health and The American Heart Association is to include physical activity on most days, if not all days. But so many things in our lives allow us to be sedentary. When you think about what life was like a century ago, when people had to go out and wash their clothes by hand and wring them out -- it required physical labor. Now you can load the clothes in the washing machine and walk away. Instead of gardening, you can hire someone to cut the grass. We live in a society that doesn't encourage exercise.
On a personal note, my husband passes a lot of commercial buildings on his way to work. They just added this drive-through donut shop a few months ago. The shop used to be down the street, and people had to get out of their cars to get their donuts. Now people are lined up in their cars, blocking traffic on both sides of the street and waiting 15 minutes to pull up to the drive-through window.
Just what are carbohydrates?
Moore: Three different types of nutrients provide energy: protein, fat and carbohydrates. They differ in their chemical structure, but they all give energy. They also have a different amount of calories per gram. Fat has 9 calories per gram. Protein and carbs have 4 calories per gram. Carbs are the most easily utilized energy in the body. They come as sugars and starches. Sugar is more easily used by the body.
Carbs give us energy. Protein helps to replenish muscle. Fats are also used as energy. All these give us fuel, but all have different functions. Foods also provide vitamins and minerals. That's another reason for concern. Certain foods provide our fiber. Fruits and vegetables and whole grains are high-carb foods with fiber. A lot of our vitamin B, A and C comes from fruits and vegetables. If we take carbs like fruits and vegetables and whole grains out of our diet, we may be missing out on these vitamins, minerals and fiber.
If you eat a piece of fruit, you get water, fiber and nutrients. It's going to take you a while to eat it and for your body to digest it. When you eat a piece of white bread, it's not going to take you as long to digest as a piece of whole grain bread. White bread doesn't have the fiber, which takes longer to chew and longer for your body to digest. Protein, fat and carbohydrates are broken down in the body at different rates, which make you feel fuller longer.
Think of adding fuel to your car. You wouldn't get very far if you don't have oil, antifreeze, transmission fluid. You need these additional things like the fiber, vitamins and minerals from carbohydrates. All these little pieces help the body processes work. We want to eat an array of foods that will give you a variety of nutrients. You can't just exclude one form of energy.
Why are people fat?
Moore: In a condition called the metabolic syndrome people have higher blood sugar levels, higher levels of lipids, high blood pressure and are overweight. These individuals produce more insulin in response to carbohydrates and are more likely to have deposits of fat.
If you have an orange in one hand and a 6-ounce glass of orange juice in the other, which one is going to take longer to eat? The orange takes a while for you to chew, and it takes longer for your body to digest it. If you eat something that is quick to eat and digest, your blood sugar rises quickly. It causes your body to make more insulin. When you eat fiber, you feel fuller; you keep your blood sugar at a more steady level.
Glucose is your brain's fuel source. When your blood sugar is low, you may feel tired and weak. This is when we often crave sweets to give us a "quick fix" to raise our blood sugar level. Foods high in sugar cause our blood sugar levels to rise rapidly, then fall. However, foods high in fiber cause a more gradual rise in blood sugar levels so you feel full longer.
That's really key. You are going to continue to lose weight if you eat a variety of foods. Let's face it. A lot of people can't diet. They stay on a diet for a few weeks and then go off it because it's too restrictive. How long are you willing to go without your favorite foods? The bottom line to weight loss is the number of calories and making permanent changes.
People really want to believe that something short term is going to give them the result they want and then they can go back to the same way of eating. I had two clients who had struggled with their weight, dieted and then regained it. Each independently came to the conclusion that they had to make permanent changes in their lifestyle and eating habits in order to successfully lose weight and keep it off.
If people are doing the low-carb diet, they are probably big meat-eaters anyway. To make permanent changes, they can still eat those foods, but they need to watch portion sizes. It may be true that some people eat too much, but they don't have to avoid all carbs. A low-carb diet is not providing them with all the nutrients they need. As an ADA spokeswoman, I would say all foods fit into a healthy diet. But there are good and bad diets. The key is variety of foods. You have to balance what you eat.
Are energy bars OK?
Moore: When you compare the calories of an energy bar to a candy bar, they're going to be about the same and the ingredients are similar. The bottom line: Does someone need this in addition to the food we talked about? You need an array of healthy foods with vitamins and minerals. One of the things in natural foods is phytochemicals or antioxidants. (Antioxidants are found in whole grains, fruits and vegetables. They help neutralize damaging free radicals produced through metabolism of food. These free radicals can cause cancer and other kinds of damage to the body.)
Phytochemicals cannot be captured in a vitamin pill or a processed food. If you are in a bind, an energy bar may be an option, but if you have the opportunity to eat real food, that is a better choice. So many natural foods are convenient and good-tasting. For instance, nuts and dried fruits.
How do you know if you are eating too many carbs?
Moore: You don't have to calculate what you eat. You don't need a pocket reference. On occasion, step on a scale. Put on a pair of pants and see how they fit. You can tell if you are gaining weight and need to cut back on calories because you can't button your pants. You are consuming more food than you need. Remember that our bodies are very efficient at storing fat.
But it's not going to be as hard to regulate calories if you are eating enough fruits and vegetables, legumes, whole grains as well as low-fat dairy products and lean meats such as fish and turkey. All these are included in the Food Pyramid in generous amounts. Sweets and fats are at the top of the pyramid so should be eaten sparingly. Often, foods high in sugar are also high in fat. And fat means more calories without much nutritional value. It doesn't take a rocket scientist to read nutrition labels and to look at the bottom of the label to see the list of ingredients. If sugar or butter is one of the first items listed, then it's going to contain significant amount of calories.
The key to weight loss is fewer calories and getting enough exercise.
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External Sources
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The American Dietetic Association
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The Cleveland Clinic
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This article was reviewed and updated June 2007.
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