from "Rust Out" by Dr. Royce Bailey, page 35

Obesity is steadily increasing in the United States has become a major public health and financial problem.  Despite years of low-fat diet recommendations, Americans continue to grow larger and fatter.  As of 2000, 64.5% of adults over the age of 20 were overweight (Body Mass Index [BMI] greater than 25), and 30% (nearly 59 million people) are obese (BMI greater than 30), compared to 23% in 1994.  Extreme obesity (BMI greater than 40) increased from 2.9% to 4.7% since 1994.  29% of the men and 44% of the women are on a diet at this time in the United States.

The public’s interest in fad diets are high.  Just look at the top 10 best selling books-most are weight loss and receipt manuals.  The basic idea is that food is fuel, and people will lose weight if they burn more calories than they consume.  

Low-Carbohydrate Diets
These diets are based on a reduction of carbohydrate intake, like the Atkins diet.

The Pros include: weight loss (mostly diuretic effect) and caloric restriction to some degree.  These include the The Zone, ar Busters, South Beach, Protein Power, Atkins, etc.  By theory, reducing your sugar intake encourages your body to oxidize its own fat, which produces ketones.  Ketones  are then excreted in the urine along with extra fluid.

The Cons of this kind of diet include: promoting thin bones (osteoporosis) because of the negative calcium balance and highly acidic (calcium wasting) diet.  The excretion of ketonic anions requires cations; if cationic minerals are not available from your food, your body will leach them from your bones.  High protein diets decrease the body’s calcium reserves and promote renal failure.  There are long-term complications with liver failure with these types of diets, too.  The worst complication is the acceleration of hardening of the arteries, because of the high saturated fat and cholesterol, low vegetable, fruit and whole grains intake.

Studies Say You Don’t Lose Weight With These Diets!
Randomized controlled trials comparing low carbo, high protein diets with low calorie diets found no weight change - up to 10% weight loss at six months to one year.  Little long-term weight loss (years) have been found.  There was a very high (drop-out) failure to follow these diets.  Long-term weight change was dependent on calorie restriction (wouldn’t you expect this), initial weight, age and duration of their diets not whether you ate exclusively protein.  HDL cholesterol went up, triglycerides went down, insulin sensitivity improved.  There was no change in total cholesterol or bad LDL cholesterol in these studies.  Weight loss in the obese is advisable, as is reduction in calories, and simple carbohydrates (sugars) but there is no scientific basis for a severe carbohydrate restricted diet.

References:
Flegal,K.M., “Prevalence And Trends In Obesity Among US Adults, 1999-2000,” JAMA, 2002;288:1723-1727.  Data from the National Health and Nutrition Examination Survey (NHANES).
Serdula,M.K., “Prevalence Of Attempting Weight Loss And Strategies For Controlling Weight” JAMA, 1999;282:1353-1358.
Bravata,D.M., “Efficacy And Safety Of Low-Carbohydrate Diets: A Systemic Review,” JAMA, 2003;289:1837-1850.  A review of 94 low carbohydrate diet studies.