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Fad Diets and Obesity - Part III: A Rapid Review of Some of the More Popular Low-Carbohydrate Diets

Posted on: Saturday, 30 October 2004, 03:00 CDT

Low-carbohydrate books continue to be some of the biggest selling publications in the United States. However, what are the similarities and differences between some of the most popular books? This overview of what some of these books advocate or discourage is important to better facilitate the discussion between the health professional and the patient interested in some of these methods. Regardless of the low-carbohydrate diet discussed with patients and whether or not health professionals agree or disagree with this approach, it is imperative that health professionals at least learn the basics of some of the more popular diets to facilitate better communication between the practitioner and patient.

It is difficult to argue with the observation that low- carbohydrate diets have become popular. However, what is actually involved or allowed or not allowed with some of the more popular diets? In part II of this series (Moyad, 2004), there was a discussion of the glycemic index (GI), which serves as the main theory behind the effectiveness of these diets. A rapid review of some of the most popular low-carbohydrate diets are included in this article to better educate the health professional and patient, regardless of whether or not someone advocates or discourages the use of these diets.

Atkins Diet (Low-Glycemic Index Diet)

First, health care professionals should understand the concept of net carbohydrates when it comes to the Atkins diet (Atkins 2002, 2004). This concept will help guide individuals through this diet. Net carbohydrates are the total carbohydrate content of a food or beverage minus or subtracting its fiber content. There are four stages to the traditional Atkins diet: induction, ongoing weight loss, pre-maintenance, and lifetime maintenance. Induction is a 14- day crash course to enter ketosis by limiting intake to 20 grams of net carbohydrates a day. Table 1 is a brief summary of the foods and beverages encouraged and discouraged during the induction phase of the Atkins diet (Atkins, 2002, 2004).

The next stage is ongoing weight loss (Atkins 2002, 2004), which can last from 2 weeks to 2 months. During this time, consumption of carbohydrates is increased gradually, by approximately 5 grams of net carbohydrates per day (5 grams = 15 almonds, 6 asparagus spears, or a half a cup of tomato juice), until the dieter discovers the maximum level he/she can eat while continuing to lose weight. When weight loss ceases, the dieter has reached his/her maximum and it is time to reduce carbohydrates again.

When the dieter is 5 to 10 pounds away from ideal body weight, he/ she is now in the premaintenance stage (Atkins 2002, 2004). This can last a few weeks or a few months. Now, weight can be lost more slowly (less than 1 pound per week). This is the time to learn what exceptions to make in the diet.

Once ideal weight is reached, the dieter can go on a lifetime maintenance diet or phase (Atkins 2002, 2004). The tough part here is to find the highest number of grams of carbohydrate that can be eaten without gaining weight back. This is probably between 40 to 60 grams of net carbohydrates per day, depending on the dieter's metabolism.

South Beach Diet (Low-Glycemic Index Diet)

This diet is the newest to sweep the country. It occurs in three phases (Agatston, 2003, 2004). The purpose of Phase 1 is to eliminate cravings. This is accomplished by eliminating all starches including all breads, potatoes, rice, and all sugars, including all fruits and alcoholic beverages. During Phase 1, high-nutrient vegetables and snacks are promoted. The South Beach Diet author says that you can "expect to lose between 7 and 13 pounds during Phase 1," which lasts 2 weeks. Table 2 offers a brief summary of the foods and beverages encouraged and discouraged during Phase I of the South Beach Diet (Agatston, 2003, 2004).

Table 1.

Foods Encouraged and Discouraged During the Induction Phase (Total Time = 14 Days) of the Atkins Diet

In Phase 2 of the diet, individuals are told to gradually add the so-called "good carbohydrates," such as whole grains and whole fruits (Agatston, 2003, 2004). Also, the author encourages a glass of red or white wine with a meal, which may actually help "slow digestion."

Once an individual has reached his/her weight loss goal, it is time for Phase 3, or the maintenance phase (Agatston, 2003, 2004). There are no real restrictions here because at this point the dieter is supposed to be knowledgeable enough to make the right decisions. For example, brown rice instead of white rice, pita bread and not white bread, and sweet potatoes instead of white potatoes. Additionally, this diet reminds individuals to follow the glycemic index and to think of the GI in three ranges: low = 55 and below, medium = 56 to 69, and high = 70 and above. The South Beach Diet recommends eating foods in the low GI range and the low glycemic load or GL range.

Table 2.

Foods Encouraged and Discouraged During Phase 1 (Total Time = 2 Weeks) of the South Beach Diet

Zone Diet (Low-Glycemic Index Diet)

This diet, developed by Barry Sears, allows dieters to enter the Zone when they figure out how many grams of protein their body needs daily (Sears & Lawren, 1995). Protein intake is spread over three meals and two snacks, never allowing going more than 5 hours during the day without eating. A good balance of carbohydrates and protein is recommended. The ideal protein-to-carbohydrate ratio is 0.75, which basically means if eating 7.5 grams of protein at one meal, 10 grams of carbohydrate should also be consumed. To simplify this math, Dr. Sears converts everything into macronutrient "blocks:" 1 protein block = 7 grams, 1 carbohydrate block = 9 grams, and 1 fat block=1.5 grams. It is recommended to eat the same number of blocks of protein, carbohydrates, and fat at each meal and snack; this allows the ideal ratio to be maintained. If, for example, if the dieter's body needs 3 blocks of protein at breakfast, then she would also eat 3 carbohydrate and 3 fat blocks. Sears lists typical macronutrient blocks to assist in constructing Zone-favorable meals. For example, 1 block of protein equals about 1 ounce of skinless chicken or turkey breast, 2 egg whites, 1 ounce of tuna, 1/4 cup of low-fat cottage cheese, or a 1/3 of an ounce of protein powder. One block of carbohydrate could be equivalent to 1 cup of cooked broccoli or zucchini, a tossed salad, a peach, 1/2 an orange or apple, or a 1/4 of a cantaloupe. One block of fat is equal to a teaspoon of olive oil and vinegar dressing, 1/2 a teaspoon of almond butter or natural peanut butter, 1 macadamia nut, 3 olives, or 1/2 a tablespoon of guacamole.

If the math involved with blocks is confusing, the dieter can attempt to grossly eyeball portions using the palm of the hand as a measurement (Sears & Lawren, 1995). The amount of protein held in the hand equals 4 blocks. To eyeball carbohydrates, the amount should be about twice as much as the size of the protein portion. The dieter can also add a little fat, such as a little salad dressing or a few olives. Also, Sears emphasis that no more than 500 calories per meal or 100 calories per snack should be eaten, which adds up to no more than 1,700 calories a day.

The timing of meals is also important (Sears & Lawren, 1995). An individual who eats breakfast at 7 am should have her next meal no later than noon. A later afternoon snack will keep the dieter in the Zone until dinner at 7 pm, and a snack before bed will keep her sleeping in the Zone until it is time for breakfast.

Sears generally recommends only low-fat protein; fiber-rich carbohydrates such as spinach, green beans, blueberries, and apples; and monounsaturated fat (Sears & Lawren, 1995). Bad carbohydrates include carrots, corn, peas, potatoes, sweet potatoes, bananas, raisins, prunes, papayas, all fruit juices (their fiber has been removed, and fiber reduces the speed at which food enters the bloodstream), most grains and breads, ice cream, granulated sugar, honey, and jelly. Also, Sears is a big fan of vitamin E supplements at 200 IU daily, because his diet supplies all the micronutrients except this one.

Again, this diet requires calculations. First, the individual daily protein requirement must be determined, which depends on the dieter's weight, level of physical activity, and percentage of body fat. Sears provides worksheets for determining percent body fat, and the dieter will also need a scale and tape measure. Once the protein requirement is discovered, the amount of carbohydrate to be eaten can be determined. The more carbohydrates eaten, the harder it is to lose weight. To lose fat, more fat must be ingested (Sears & Lawren, 1995). To enter the Zone of permanent weight loss, food must be eaten "in a controlled fashion and in the proper proportions - as if it were an intravenous drip." This means reducing carbohydrate intake to approximately 40% of total calories (USDA recommends 60%), making up the loss by doubling the standard protein amount to 30%, and getting 30% from fat (the USDA maximum), mostly from mono- unsaturated fat sources. Sears calls this concept the 40-30-30 diet. Finally, it is important to realize that Sears classifies the bad carbohydrates as the ones that have a high glycemic index.

Conclusion

A discussion of some of the more popular non-low-carbohydrate diets and some recent clini\cal research that supports and refutes these methods will be included in Part IV of this series. In the meantime, it seems imperative to at least discuss some of the basic concepts of the more popular low-carbohydrate diets. Health professionals should be better equipped to discuss the methods or principles involved with low-carbohydrate diets after reading this article. If a greater overview of these diets are needed, the health professional should refer to the specific low-carbohydrate book in question. Regardless, knowing the low-carbohydrate vernacular seems more important than ever because patients will inquire about those diets.

References

Agatston, A. (2004). TAe South Bench diet: Good fats good carbs guide. New York: Rodale Press.

Agatston, A. (2003). The South Beach diet. New York: Rodale Press.

Atkins, R.C. (2004). The Atkins essentials. New York: Harper Collins Publishers.

Atkins, R.C. (2002). Dr. Atkins new diet revolution. New York: Harper Collins Publishers.

Moyad, M. (2004). Fad diets and obesity - part II: An introduction to the theory behind low-carbohydrate diets. Urologic Nursing, 24(3), 210-213.

Sears, B., & Lawren B. (1995). The Zone. New York: Harper Collins Publishing.

Mark A. Moyad, MD, MPH, is the Phil F. Jenkins Director of Complementary/Preventive Medicine, University of Michigan Medical Center, Department of Urology, Ann Arbor, MI.

Copyright Anthony J. Jannetti, Inc. Oct 2004

Source: Urologic Nursing

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