What is the Atkins Diet?
Developed by the late Dr. Robert C. Atkins, this is a low-carbohydrate, high protein diet. It is a four-phase plan: a two-week jump start allows nearly no carbohydrates; the second phase allows more carbohydrates but is still quite limiting; the third pre-maintenance stage comes into play when you have just a few pounds left to lose; and the final stage is maintenance.
Unless you have only a few pounds to lose, most of your time will be spent in phase two.
How does the Atkins Diet work?
While calorie counting is not called for, counting net carbohydrates is a must. The Net carbohydrate is not the number listed in the nutritional information box. The net carbohydrate number subtracts the carbohydrate derived from fiber and sugar alcohol. That number is normally prominently displayed on pre-package Atkins foods.
The first phase is designed to start turning your body into a fat burning machine instead of a carbohydrate burning machine. This is done by starving your body of carbohydrates.
What does research say?
The official web site for the diet claims you could lose 15 pounds during that first two weeks but couches that with a disclaimer saying that result is not typical.
The Atkins web site also provides research information about low-carbohydrate diets. While includes a 12-month study that shows Atkins dieters lost more weight than others assigned to the Zone, LEARN, or Ornish plans, there are many more studies that show long-term weight loss is often similar when comparing low-carbohydrate diets to others. One year-long study on the site concluded that "weight loss was similar between groups" and another found that while subjects on the low-carbohydrate diet had lost more weight than subjects on a conventional diet at 3 and 6 months, "the differences were not significant at one year."
Note: This diet is sometimes mistakenly referred to as the Adkins Diet.