Diet Reviews

Author: Craig Coghlin B.A., CPT, CSCS, ART, D.C. (cand.)

Low Carbohydrate Diets

These diets became popularized with the Atkins Diet, which restricts the carbohydrates you eat in your diet. Low carb diets have been criticized as being no better than simple calorie reduced diets. The backbone of these diets centres around Glycemic index.

Approximately 200 g of glucose is required by the human body every day for its basic functions. If glucose levels dip below 40 mg/Dl in the blood, coma, seizure, and death may occur. On the flip side, levels above 180 mg/Dl can cause problems such as diabetes, hypertension, and atherosclerosis.

The Atkins diet is a low glycemic index diet. Atkins looks at NET carbohydrates in a meal, which is basically the amount of carbs minus the amount of fibre in the food. The first step in the Atkins diet is induction, which teeters into ketosis by limiting the net carbs per day to 20 grams. This lasts for 14 days.

The next stage, ongoing weight loss, slowly reintroduces carbs into the diet by a maximum of 5 grams per day. The patient will increase the number of carbs until they discover the max amount of carbs they can handle while still losing weight. The last two stages in the diet occur when the patient is close to their ideal weight.

The South Beach Diet is another example. The first stage of this diet is to eliminate all starches, including alcohol and fruits. The authors of the diet say that 7-13 lbs. of weight loss can be expected in this two week stage. In the second phase, “good” carbs are reintroduced in the form of complex carbs and fruit. They also encourage wine with meals in this stage. The final stage is simply maintenance. The authors assume the dieter will be able to make better decisions now in their meal choices.

The Zone Diet is also a low glycemic index diet. Firstly the patient figures out how much protein their body needs, then spreads this out over three meals. In this diet the author suggests splitting the number of carbs, protein, and fat into “blocks” and eating the same amount of blocks of each nutrient in each meal. One major fall back of this diet is that it involves a lot of math calculations to determine the proper amount of each nutrient to be eating at each meal.

Other Fad / Popular Diets

The Ornish Diet involves patients being dedicated to a low-fat vegetarian diet. Weight watchers is a generally low calorie diet that focuses on small stepwise progressions.

So what’s wrong with these diets?

The main issue with these diets is that their long term safety and effectiveness has not been proven. People entered into low carb diets have been shown by several studies to lose weight, often more than people on a low fat diet, but their may be complications with a low carb diet. One study noted that several participants had to drop out due to a dramatic rise is LDL. The low carb participants also reported many more adverse effects compared to the low fat group including constipation, headaches, bad breath (due to ketosis), muscle cramps, diarrhea, weakness, and rashes. Also, in high protein diets, the
by-product of protein metabolism is nitrogen. Too much nitrogen excretion can damage the kidneys. Excessive protein intake also can boost uric acid production, which can cause gout and kidney stones.

A case study was also completed that outlined a woman who had severe daily vomiting and shortness of breath, indicating that by following the Atkins diet she had entered into sever ketoacidosis. Dietary ketosis is a normal phenomenon, but diabetic ketoacidosis can be life threatening. Thus, for a

iabetic person that enters into this diet (whether they are aware of their condition or not) and subsequently increase the ketone bodies in their system, there could be an overload. When excessive ketones are produced, the kidneys have to work harder to filter them. The body goes into starvation mode and metabolism slows down. Then carbohydrates are burned more slowly. Many supporters of the Atkins diet though claim that the ketones produced would be at a level too low to cause acidosis.

The reported weight loss in low carb diets has been argued as well. Many critics conclude that the weight loss people experience in these diets is not from the restriction in carbs but rather the decrease in calories and length of diet. They also note that the low carb diets cause increased weight loss in 3-6 months, but thereafter, the weight loss is no different than a normal calorie reduced diet. Some might also argue that the increased initial weight loss is in large part the water retained with the carbs (with every one gram of carbs, the body stores 3 grams of carbs). Yet as usual, the research seems split as to the direct safety of the Atkins diet. Some claim that HDL levels, triglyceride concentrations, and insulin sensitivity are all improved, while other report the opposite.

The main downfall of the Atkins diet that no one can deny is in its nutritional deficiencies
—too much fat and saturated fat, too little fiber, too few fruits. The South Beach and Jenny Craig diet plans are lacking in any sort of clinical evidence. As mentioned earlier, the biggest problem with all of these diets is simply the adherence. In many of the randomized studies, drop-out rates were as high as 45%. And those that did manage to stay with the diet were not very strict in following the diet exactly as it requests.

About the Author: Craig Coghlin, B.A., CPT, CSCS, ART® Provider, D.C. (candidate) is currently the owner of Empowerment Personal Training Services based out of Toronto. He is a Clinical Intern at the Canadian Memorial Chiropractic College in Toronto, Ontario and will complete his doctorate of chiropractic in June 2007. Craig has been a personal trainer for over five years and a Certified Strength and Conditioning Specialist for three years. In this time he has worked with all types of clients from beginners to professional athletes. If you have any questions or comments, please email him at

Diet Review References

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Daniels J. Fad diets: Slim on good nutrition. Nursing. 2004. Vol. 34 (12), pg. 22.

Dehpahlaven J. Fad diets analyzed. Today’s Chiropractic. 2004, March/April. Pg. 53-57.

Lessnau K. Correspondence. The Lancet. 2006, July. Vol. 368, pg. 23.

Moyad M. Fad diets and obesity: Part II. Urologic Nursing. 2004, June. Vol. 24 (3).

Moyad M. Fad diets and obesity: Part III. Urologic Nursing. 2004, October. Vol. 24 (5).

Moyad M. Fad diets and obesity: Part IV. Urologic Nursing. 2005, February. Vol. 25 (1).

Yancy W, Olsen M, Guyton J, Bakst R, Westman E. A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet To Treat Obesity and Hyperlipidemia. A Randomized,
Controlled Trial. Annals of Internal Medicine. 2004, May. Vol. 140, pp. 769-777.