Monday, September 6, 2010
Weight-loss Myths, Part I
We do this because, without you knowing it, the media has brainwashed us into believing the world is flat, and that and the sun revolves around the earth, when it comes to exercise, nutrition, and weight-loss. Why do they do this? Well, according to ResearchWikis.com:
"The sports drinks market is approximately US $300 billion in terms of sales worldwide in 2005."
Need I say more?
Just like Galileo was persecuted because he said the earth revolves around the sun, we too get strange looks and sometimes heated tempers when we say things like:
"Drink chocolate milk instead of protein drinks; and eat all the carbs you want, even after 6 o'clock."
So, for the next few days we are going to share some weight-loss myths that the National Academy of Sports Medicine outlines in their "Solutions to Weight Management" course. Let's tackle our first myth:
Probably more widely debated than any other diet in the scientific as well as the consumer literature is the
high-protein/low-carbohydrate diet. These plans have been a part of diet lexicon since the mid-1800s with
William Banting’s Letter on Corpulence (2). Billed as the “world’s first diet book,” Banting’s work recommended eating lots of meat, a few vegetables, and avoiding those foods that he previously over consumed.
Today the term low-carb diet is often thought of as synonymous with the Atkins Diet, named after the
celebrated cardiologist, Dr. Robert Atkins. Popularly known as “The Atkins Diet” or just “Atkins,” the
program restricts carbohydrate consumption, usually for weight control. Foods high in digestible carbohydrates are limited or replaced with foods containing a higher percentage of protein and fats or other
foods lower in carbohydrates (e.g. green leafy vegetables). Dr. Atkins popularized his work in a series of
books, starting with Dr. Atkins’ Diet Revolution in 1972. In his revised book, Dr. Atkins’ New Diet Revolution, he modified or changed some of his ideas but remained faithful to the original concepts. The Atkins books have sold more than 45 million copies in the past 40 years (3).
During the late 1990s and early 2000s, low-carbohydrate diets ranked among the most popular diets in
the U.S., and versions of this diet (the Zone Diet, the Protein Power Lifeplan, the Go-Lower Diet, and
the South Beach Diet, among others) remain popular today. In most formats, the carbohydrate-modified
(low-carbohydrate/high-protein) diet is a ketogenic diet, which induces a state of ketosis through severe
limitation of dietary carbohydrates. Ketosis occurs in metabolism when the liver converts fat into fatty
acids, and ketones, the byproduct of incomplete fat metabolism, reach high levels in the blood (4).
A compendium of research has been done examining the manipulation of macronutrient content to produce
a metabolic advantage for weight loss. No consensus in the literature shows that low-carbohydrate diets
produce significantly greater rates of weight loss or longer-term weight loss maintenance when compared
to more conventional low-fat diets (5, 6, 7).
If high-protein diets do produce greater amount of weight loss in some studies, what are the suggested
mechanisms? Scientists suggest that several mechanisms may be responsible for the weight loss seen with
• The severe restriction of carbohydrate depletes glycogen (stored carbohydrate) supply, leading to excretion of bound water.
• The ketogenic nature of the diet may suppress appetite, leading to reduced intake.
• The high-protein content of low-carbohydrate diets may provide greater hormonally mediated
satiety, thereby reducing spontaneous food intake.
• The self-selection from limited food choices may lead to a decrease in energy intake.
In a review article of 107 published research studies designed to evaluate changes in weight among adults
using low-carbohydrate diets in the outpatient setting, Bravata (8) found that participant weight loss while
using low-carbohydrate diets was principally associated with decreased caloric intake and increased diet
duration, but not with reduced carbohydrate content. In other words, the calorie reduction and negative
energy balance that occurs on these diets induce weight loss. It is worth noting that many studies in this
area are limited by a high attrition (drop-out rate) and by suboptimal dietary adherence of the enrolled
Where does this leave Health and Fitness Professionals in regards to low-carbohydrate diets and questions
from clients? Recall that the acceptable macronutrient distributions range (AMDR) is 45% to 65% of total calories from carbohydrate. According to science supporting the AMDR, anyone eating an adequate
energy provision (for weight loss) from nutrient-dense foods with between 45% and 65% of total calories
from carbohydrates will fall within the recommendation.
That said, the emphasis of nutrition counseling today is to preserve (as much as possible) the way clients
like to eat. Weight loss requires habit changes, but behaviorists who specialize in weight loss suggest that
if client preferences can be preserved, they should be. In other words, if a client loves sweet potato, whole
grain bread, oatmeal, and legumes (all nutrient-dense carbohydrates), they may not be very compliant
with a program that provides only 45% of total calories from carbohydrate. They also do not need to be
on a low-carbohydrate diet to lose weight, as any reduction in calorie intake below daily expenditure will
induce weight loss.
Low-carbohydrate diets may work for some people, and as long as they are within the AMDR and provide
nutrient-dense foods, they should not present a health risk. But they are not for everyone. Flexibility on
behalf of the Health and Fitness Professional and client is critical to weight-loss success (9, 10). In other
words, the difficulty for most people lies not in the diet, but in adherence to the diet. The closer the
weight-loss program follows the way they like to eat, the more successful they are going to be. Therefore,
clients can choose to simply decrease the frequency or portion sizes of the foods they normally consume
to cut calories, or make acceptable dietary changes to reduce intake.
1. Kantrowitz B, Kalb C. Diet Hype: How the Media Collides with Science. Newsweek. March 13,
2. Banting, W. Letter on Corpulence, 1863. USA: New York: Cosimo Classics; 2005.
3. Astrup A. Larson TM, Harper A. Atkins and Other Low-carbohydrate Diets: Hoax or an Effective
Tool for Weight Loss? Lancet. 2004; 364:897–9.
4. Whitney E, Rolfes SR Eds. Understanding Nutrition. 11th ed. Belmont, CA Thomson Higher
Education; 2008, p.113
5. Eisenstein J, Roberts SB, Dallal G, Saltzman E. High-Protein Weight Loss Diets: Are They Safe and
Do They Work? A Review of the Experimental and Epidemiological Data. Nutrition Reviews. 2002;
6. Pittas SG, Roberts SB. Dietary Composition and Weight Loss: Can We Individualize Dietary
Prescriptions According to Insulin Sensitivity and Secretion Status? Nutrition Reviews. 2006;
7. Schoeller DA, Buchholtz AC. Energetics of Obesity and Weight Control: Does Diet Composition
Matter? J Am Diet Assoc. 2005;105 (5):S24–S28.
8. Bravata DM et al. Efficacy and Safety of Low-carbohydrate Diets: A Systematic Review. JAMA.
9. Nonas CA, Foster G. Setting Achievable Goals for Weight Loss. J Amer Diet Assoc. 2005;
10. Reeves R, Bolton MP, Gee M. Dietary Approaches, Practical Application. In: Foster GD, Nonas CA
eds. Managing Obesity: A Clinical Guide. Chicago, IL. ADA; 2004:98–117.
11. Ebbeling CB, Leidig MM, Feldman HA, Lovesky MM, Ludwig DS. Effects of a Low-glycemic Load vs.
Low-fat Diet in Obese Young Adults: A Randomized Trial. JAMA. 2007;297(19):2092–102.
12. Ebbeling CB, Leidig MM, Sinclair KB, Seger-Shippee LG, Feldman HA, Ludwig DS. Effects of an Ad
Libitum Low-glycemic Load Diet on Cardiovascular Disease Risk Factors in Obese Young Adults.
Am J Clin Nutr. 2005;81(5):976–82.
13. Ball SD, Keller KR, Moyer-Mileur LJ, Ding YW, Donaldson D, Jackson WD. Prolongation of
Satiety after Low versus Moderately High Glycemic Index Meals in Obese Adolescents. Pediatrics.
14. National Institutes of Health. Very Low-Calorie Diets. National Task Force on the Prevention and
Treatment of Obesity. JAMA. 1993; 270(8):967–74.
15. Heymsfield SB, van Mierlo CAJ, van der Knaap HCM, Heo M, Frier HI. Weight Management
using a Meal Replacement Strategy: Meta and Pooling Analysis from Six Studies. Int J Obes. 2003.
16. Hill J, Wing R. Long-term Weight Loss and Breakfast in Subjects in the National Weight Control
Registry. Obes Res. 2002;10(2):78–82.
17. Colles SL, Dixon JB, O’Brien PE. Night Eating Syndrome and Nocturnal Snacking: Association with
Obesity, Binge Eating and Psychological Distress. Int J Obes (London). 2007;31(11):1722–30.
18. Elia M. Organ and Tissue Contribution to Metabolic Rate. In: Kinney JM, Tucker HN, eds. Energy
Metabolism. Tissue Determinants and Cellular Corollaries. New York: Raven Press, 1992:61–77.
19. Wang, Z., et al. Resting Energy Expenditure: Systematic Organization and Critique of Prediction
Methods. Obesity Research. 2001;9(5):331–6.
20. Wolfe RR. The Underappreciated Role of Muscle in Health and Disease. Am Journal Clin Nutr. 2006;
21. Haltom R.W. et al. Circuit Weight Training and its Effects on Excess Postexercise Oxygen
Consumption. Medicine & Science in Sports & Exercise. 1999;31:1613–8.
22. Ballor DL, Katch, VL, Becque MD, Marks CR. Resistance Weight Training During Caloric
Restriction Enhances Lean Body Weight Maintenance. Am. J. Clin Nutr. 1988;47:19–25.
23. Donnelly JE, Pronk NP, Jacobsen DJ, Pronk SJ, Jakicic JM. Effects of a Very-Low-Calorie Diet and
Physical-Training Regimens on Body Composition and Resting Metabolic Rate in Obese Females.
Am. J. Clin Nutr. 1991;54:56–61.
24. Sweeney ME, Hill JO, Heller PA, Baney R, DiGirolamom M. Severe vs. Moderate Energy Restriction
With and Without Exercise in the Treatment of Obesity: Efficiency of Weight Loss. Am. J. Clin Nutr.
25. McArdle WD, Katch FL, Katch VL. Essentials of Exercise Physiology. Media, PA: William and