Walk through any grocery store today and, chances are, you will be bombarded by a plethora of food offerings billed as “low-carb.” And it’s no wonder, considering that anywhere from 10 to 24 million Americans have jumped on the low-carb diet bandwagon (Reuters 2004). But is the low carb diet destined to fall by the wayside like the low-fat craze of the 1990s?
Many food experts think so. Here’s why: A “true” low-carb diet requires that certain food items be entirely eliminated. When carb options are severely restricted in this way, variety is limited and people do tend to eat less. However, the reality is that most Americans are confused about anything classified as a carbohydrate and are still making poor dietary choices. (If you don’t agree, see page 56 for the types of carbs most favored by the American public.) In fact, when our clients start to question the nutritional value of a banana—once considered the “perfect food”—it’s clearly time to educate the public about the very real benefits of eating healthy carbohydrates.
This article will examine past and current eating trends, the role of carbohydrates in the diet, the latest scientific evidence and the movement by food manufacturers to capitalize on the low-carb craze. To help you separate the wheat from the chaff, you will learn which carbs are healthier and you’ll get some practical suggestions on serving sizes and nutrient density.
According to Dr. Atkins’ New Diet Revolution, which many consider the bible of the low-carb craze, Americans have already done the “low-fat” thing and been unsuccessful (Atkins 2002). To some extent, this is true. Researchers who studied food trends between 1989–1991 and 1994–1996, when low-fat diets were all the rage, did find significant increases in total calories and total fat intake (Chanmugam et al. 2003). They also found that the caloric increase was due to an increase in carbohydrate consumption. So it would stand to reason that carbs are the culprit in weight gain, no?
Not necessarily, say nutritionists. A closer look at the food trend data found in this study revealed that the additional carbohydrates consumed were primarily in the form of overly processed beverages, food mixtures, grain snacks and pastries (Chanmugam et al. 2003). Americans failed to embrace the concept of eating more whole grains, fruits and vegetables as a natural way to decrease fat. No wonder these low-fat diets failed. The problem is that the blame for a heavier America was placed on the lowly carbohydrate, not on the extra calories consumed.
One way to ensure that we don’t repeat past dieting mistakes is to educate our clients on the important role that carbs play in a healthy food plan and on ways to choose the healthier carb options available today.
Carbohydrates provide the body with its most readily available source of fuel: glucose. During normal metabolism, carbohydrates act as the primary fuel for most cells in the body, especially those in the brain. The National Academy of Sciences Food and Nutrition Board (FNB) currently recommends that people consume 130 grams (g) per day of dietary carbohydrate to accommodate the body’s needs. The range of carbohydrate intake in terms of a percentage of total calories consumed should be 45%–65% (225–325 g for people eating 2,000 calories per day) (FNB 2002).
One of the main functions of carbohydrates is to maintain constant levels of blood glucose in the body. Dietary intake and glucose (glycogen) stores are constantly manipulated to maintain blood glucose levels within a normal range. During exercise, the muscles utilize glycogen as fuel and the body relies on carbohydrates as exercise intensity increases (Insel et al. 2002).
If carbohydrate stores are not sufficient, the body is able to generate glucose from glycogen stores or existing protein stores in the muscles, organs and tissue. However, when protein is used for energy, other bodily functions—such as tissue growth, maintenance and repair—can be severely compromised. During periods of prolonged starvation, the body can adapt and utilize ketones for energy. Ketones are generated via fat metabolism when the carbohydrate supply is too low; however, ketone buildup in the bloodstream can result in a life-threatening condition known as ketosis. The minimum carbohydrate intake needed to maintain normal metabolic function and prevent ketosis is 50–100 g per day (Insel et al. 2002).
Although the body will adapt to various levels of caloric intake, it prefers to use carbohydrates for fuel. Unfortunately, it is unable to distinguish naturally occurring carbs from carbs that have been refined during food processing (Sigman-Grant & Morita 2003). Put simply, naturally occurring carbs provide an abundance of vitamins, minerals, fiber and other nutrients and are most readily found in whole foods, such as fruits, vegetables, whole grains and dairy products. Refined carbs have been processed to increase palatability and shelf life but are often high in calories and low in nutritional value.
The glycemic index (GI) is a ranking system that determines how quickly a carbohydrate food will raise and lower blood glucose levels in the body. A food with a higher GI stimulates a sharper peak in blood glucose levels, which in turn increases insulin release. This results in a higher glycemic response, in which glucose is cleared more rapidly from the bloodstream. Conversely, a food with a lower GI causes less insulin to be released, which lessens the glycemic response (Foster-Powell et al. 2002).
The GI of a particular food can be affected by many factors, including the amount of fat, protein and dietary fiber it contains, how it is processed, how ripe it is, and how and when the food is consumed (e.g., alone or as part of a meal or snack). While all these variables are important, clients need to realize that many convenience foods are primarily refined carbohydrates, which typically have higher GIs than naturally occurring carbs. Some studies suggest that high-GI carbohydrates may increase hunger and promote overeating relative to lower-GI carbs (Roberts 2000). (For a more in-depth discussion of the GI, see “Understanding the Glycemic Index” by Cathy Leman, RD, LD, in the October 2003 issue of IDEA Health & Fitness Source.)
In general, naturally occurring carbs, such as bananas, tend to have lower GIs and help keep hunger at bay. Although the body can readily metabolize refined carbs, like candy and white bread, these higher-GI foods provide less than optimal satiety and nutrient density. That’s why most nutrition experts recommend that we limit our intake of highly refined carbs and instead choose nutrient-dense, naturally occurring carbohydrates.
For a carbohydrate to be considered nutrient dense, it must contain a high level of nutrients in comparison to the number of calories contained in a single serving. Carrots, spinach and broccoli are perfect examples of nutrient-dense carbs because they all provide a wealth of vitamins and minerals but contain very few calories.
On the other end of the spectrum, nutrient-deficient carbs offer few if any nutrients when stacked up against the calories in a given serving; for this reason, these foods are often said to yield “empty calories.” Case in point: soft drinks, which provide an abundant source of empty calories and have been linked to the obesity epidemic (Chanmugam et al. 2003; Coulston & Johnson 2002). See “Comparing Carb Choices” above, for a look at how soft drinks contrast with vegetables in terms of nutritional value. For a look at which carbs give you the biggest nutrient boost per calorie, see “20 Most Nutrient-Dense Carbs” on page 59.
An easy way clients can get more nutrient-dense carbs is to buy naturally occurring carbs over refined ones. The more a food is manipulated during processing, the less nutrient value the product retains. For example, to create refined white flour, the nutrient-rich germ and bran are removed from the whole wheat, resulting in an end product that is so deficient in nutrients it requires enrichment! That’s why all products made with refined white flour are now enriched with vitamins, iron and folic acid.
Carefully reading labels to identify whether products contain refined or whole-grain ingredients is an important step toward making healthier carbohydrate choices. Clients should steer clear of any food whose first ingredient is listed as “refined flour, enriched flour, unbleached flour” or just plain “wheat flour” (Hurley & Liebman 2001). They should opt instead for products consisting mainly of whole-grain ingredients, such as oatmeal, brown rice, barley, corn, rye, flax, couscous and whole wheat.
Many of the refined low-carb products on the market today have been manipulated to reduce the foods’ carbohydrate content; during processing, the carbs are replaced with sugar alcohols. Also known as polyols, these substances contain neither sugar nor alcohol. Instead, sugar alcohols are carbohydrates that are not wholly digestible and provide an average caloric density of 2 calories per gram, compared to the 4 calories per gram found in traditional carbs. Manufacturers add sugar alcohols to create a product that is lower in calories and sugar, retains moisture, has more texture and has a lower freezing point (Warshaw & Powers 1999). Sugar alcohols are often found in chocolate and candy, frozen desserts and energy bars.
These alcohols can appear on a product’s ingredient list either under “Sugars” or in the “Total Carbohydrate” category. However, keep in mind that manufacturers are not currently mandated by law to list sugar alcohols on “Nutrition Facts” labels. So our clients should be on the lookout for any of the following terms used to identify sugar alcohols:
Sugar alcohols are similar to dietary fiber in that they are not completely digested by the body, resulting in a lower caloric content and less dramatic swings in blood glucose levels. Also like dietary fiber, sugar alcohols—especially mannitol and sorbitol—can increase the potential for gastrointestinal effects such as gas, flatulence and diarrhea. Because of this, the U.S. Food and Drug Administration (FDA) has issued a warning notice that “excess consumption [of sugar alcohols] may have a laxative effect.” Currently, this notice is required on products only if their regular consumption could lead to daily intake of at least 50 g of sorbitol or 20 g of mannitol (Greeley 1992). However, there is the potential that people will eat more than one product containing these ingredients each day, thereby increasing the risk of side effects. The bottom line here is that, even though sugar alcohols can reduce carb consumption, our clients should eat processed carbs in moderation to avoid undesirable gastrointestinal effects.
Another method that food manufacturers use to lower the carb content of a product in order to capitalize on the low-carb craze is to replace carbohydrates with a nonnutritive, artificial sweetener. The FDA currently approves the following nonnutritive sweeteners for consumption in the United States:
- aspartame (Equal®, NutraSweet®)
- sucralose (Splenda®)
- acesulfame potassium (Sunett®)
- saccharin (Sweet ’N Low®)
These artificial substitutes vary widely in terms of sweetness, but they are similar in that the body does not completely metabolize them, which is why they are termed “nonnutritive.” To meet FDA approval, all have undergone extensive research regarding safety and consumption. In fact, the American Dietetic Association itself has approved the use of nonnutritive sweeteners to lower the intake of sugar and calories within set guidelines (ADA 2004). Acceptable Daily Intake levels have been set and are monitored by the FDA to ensure that consumption of nonnutritive sweeteners stay well below these established limits.
Although nonnutritive sweeteners can help lower caloric and sugar intake, moderation is certainly needed. That’s why clients need to be reminded to check ingredient labels carefully and find out exactly what products contain. Only then can they decide whether more natural substitutions are warranted. Clients also need to realize that nonnutritive sweeteners do not enhance the nutrient profile of a food, nor do they necessarily promote overall health.
So what’s a shopper to do when wandering those low-carb food aisles? The take-home message to emphasize to your clients is to choose their carbs carefully from all the choices available today.
Bread & Pasta. Two products that are the most popular for people doing the low-carb diet are bread and pasta, both of which are already highly refined during food processing. Further manipulating these foods to make them lower in carbohydrates does not make them nutrient dense and certainly does not make them calorie free. And it’s not just plain old white bread that food manufacturers are targeting. Many are reducing the carb content in their whole-grain breads by replacing the wheat flour with wheat gluten and wheat protein, while others are adding dietary fiber as a bulking agent (Liebman 2004).
Take-Home Message: When selecting any grain product, check the label to see if the first ingredient is a whole grain. Buy whole-grain breads that contain at least 2 g of fiber per serving and grain cereals with 4 g of fiber per serving. Be aware of your grain choices and try to consume at least three whole-grain products each day. Remember to check the ingredient labels for artificial sweeteners, such as sucralose, which offer little or no carbohydrate or caloric savings. And keep in mind that cereals and yogurt may contain sugared fruit, such as raisins; buy the unsweetened versions and add a dollop of frozen or fresh fruit.
Dairy Beverages. Contrary to popular opinion, dairy products can be a healthy source of carbohydrates. They provide a wealth of naturally occurring nutrients, such as calcium, riboflavin and vitamin B12. Low- or nonfat dairy products are also low in calories and saturated fat (National Dairy Council 2004).
Take-Home Message: Most low-carb versions of dairy products contain a slew of artificial sweeteners, such as sucralose and acesulfame potassium; one popular milk product billed as low carb contains 17 artificial ingredients! Compare this to regular 2% milk, which contains only three ingredients (i.e., milk and the fortifying nutrients vitamins A and D). That’s why clients need to be made aware of the food additives in low-carb products on the market today. And if they do indulge in these options, they should do so in moderation.
The recommendations made in this article are easy ways clients can incorporate healthier carbohydrate choices, which in the long run will substantially enhance their overall nutrient profile. But the lesson we have learned from past failed food trends is this: The key to the low-carb diet is to incorporate more nutrient-dense carbs in the diet, not to replace nutrient-deficient carbs with their lower-carb counterparts.
In fact, the Atkins approach to the low-carb diet actually supports the concept of replacing empty-calorie carbs with healthy, natural choices, such as fruits, vegetables and some whole grains. According to Atkins himself, eating nutrient-deficient carbohydrate foods instead of vegetables and other nutrient-dense foods will not foster “long-term health” (Atkins 2002).
The problemwith the low-carb diet is that many of today’s new, nutrient-deficient low-carb products are setting us up to potentially eat more—a lesson we already learned after the low-fat diet debacle. When it comes to low-carb product variety, less may just prove more.
The bottom line is that carbohydrates continue to be a superior choice for fueling the body the way nature intended. At the end of the day, clients need to be reminded that the nutrient density of a carbohydrate counts way more than the number of grams consumed. The next time a client asks you about the low-carb diet, do your part to explain the bigger nutrition picture. Emphasize that it is better to eschew unnatural, processed, refined carbs and replace them with whole grains, fruits and vegetables.
No wonder carbohydrates have gotten such a bad reputation lately.Here’s a sampling of the overly processed and refined carbs that Americans eat most often:
- white bread
- cold breakfast cereals
- white rice
- soft drinks
- French fries
What a difference a carb makes! Teach your clients the value of choosing nutrient-dense foods, such as broccoli, and rejecting the empty calories contained in nutrient-deficient products, like soda.
Check out these websites for more information on choosing carbohydrates:
www.cspinet.org/nah/: Nutrition Action Health Letter
www.Med2000.com: offers home-study continuing education courses
The following carbohydrate sources are a representation of brightly colored fruits and vegetables that provide good dietary fiber and a rich nutrient profile.
American Dietetic Association (ADA). 2004. Position of the American Dietetic Association: Use of nutritive and nonnutritive sweeteners. Journal of the American Dietetic Association, 104, 255–75.
American Institute for Cancer Research (AICR). 2003. The New American Plate for Breakfast. Available at www.aicr.org.
Atkins, R.C. 2002. Dr. Atkins’ New Diet Revolution (pp. 3–6 & 223). New York: Avon Books.
Chanmugam, P., et al. 2003. Did fat intake in the United States really decline between 1989–1991 and 1994–1996? Journal of the American Dietetic Association, 103 (7), 867–72.
Coulston, A.M., & Johnson, R.K. 2002. Sugar and sugars: Myths and realities. Journal of the American Dietetic Association, 102 (3), 351–53.
Food and Nutrition Board (FNB), Institute of Medicine, National Academy of Sciences. 2002. Dietary reference intakes for energy, carbohydrates, fiber, fat, fatty acids, cholesterol, protein, and amino acids. www.iom.edu/report.asp?id=4340; retrieved October 9, 2004.
Foster-Powell, K., et al. 2002. International table of glycemic index and glycemic load values: 2002. American Journal of Clinical Nutrition, 75 (5), 5–56.
Greeley, A. 1992. Not only sugar is sweet. FDA Consumer. www.fda.gov/bbs/topics/ CONSUMER/CON00133.html; accessed August 13, 2004.
Hurley, J., & Liebman, B. 2001. No matter how you slice it: Finding the best breads. Nutrition Action Health Letter, 28 (8), 13–15.
Insel, P., et al. 2002. Carbohydrates. In J.H. Hauck (Ed.), Nutrition (2002 Update, pp. 98–131). Boston: Jones and Bartlett Publishers.
Leman, C. 2003. Understanding the Glycemic Index. IDEA Health & Fitness Source, 21 (9), 62–65.
Liebman, B. 2004. Cashing in on the low-carb craze. Nutrition Action Health Letter, 34 (2), 8–11.
National Dairy Council. 2004. Dairy foods’ contribution to nutrient dense diets. Dairy Council Digest, 75 (1), 1–6.
Reuters. 2004. Is the low-carb backlash beginning? http://cnn.health; retrieved November 1, 2004.
Roberts, S.B. 2000. High-glycemic index foods, hunger, and obesity: Is there a connection? Nutrition Reviews, 58 (6), 163–69.
Schirmer, G. 2004. The Diet Revolution. Bedford, TX: MED2000 Inc.
Sigman-Grant, M., & Morita, J. 2003. Defining and interpreting intakes of sugars. American Journal of Clinical Nutrition, 78 (Suppl.), 815S–26S.
Tufts University. 2003. Do the extra pounds result from too much food or too little exercise? Tufts University Health & Nutrition Letter, 21 (2), 3.
Tufts University. 2003. Low-carb craze, or low-carb crazy? Tufts University Health & Nutrition Letter, 21 (8), 4–5.
United States Department of Agriculture. 2004. National Nutrient Database for Standard Reference, Release 17. www.nal.usda.gov/fnic/etext/000105.html.
Warshaw, H.S., & Powers, M.A. 1999. A search for answers about foods with polyols (sugar alcohols). The Diabetes Educator, 25 (3), 307–21.
Willet, W.C. 2001. Eat, Drink and Be Healthy. New York: Free Press.
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