The late Dr. Robert C. Atkins developed this low-carbohydrate, high-protein weight-loss plan which was publicized in his best-selling book, The Atkins Diet Revolution. Dr. Atkins promoted the plan as not only a quick weight-loss diet but as a change in eating for a lifetime. The diet was extremely popular allowing individuals to consume large quantities of meat and high-fat foods without considering caloric restrictions.
The foundation of the Atkins Plan is a reduction of carbohydrates. The diet has evolved over the years to currently offer two options. With Atkins 20™, the starting point (Phase 1, Induction) is 20 g of “Net Carbs” (carbohydrate minus grams of fiber) per day. The Atkins 40™ allows a starting point of 40 g of Net Carbs per day. Both plans allow for an increase in carbohydrates. One plan adds foods one at a time and the other raises the carbohydrate portion-size allowance as individuals approach their weight loss goals.
The Atkins 20TM (the original plan) includes a four-step process beginning with a two-week induction phase with carbohydrates restricted to 20 g Net Carbs per day. The carbohydrates are derived primarily from low-glycemic, nutrient-dense, fiber-rich carbohydrates such as leafy green salads and other non-starchy vegetables. The client is instructed to consume 4–6 oz. of protein at each meal and enough natural fat to feel satiated. Trans fats are eliminated.
The protein is derived from a variety of sources to include meat, fish, poultry, eggs, and vegetable-based proteins such as tofu. Adequate fluid (water preferred) intake along with exercise and a complete multivitamin/mineral supplement is recommended in order to obtain optimal nutrition. Dairy intake is limited because of its carbohydrate content, therefore, calcium supplementation is recommended.
The second phase of the program is referred to as the ongoing weight loss phase. During this phase, carbohydrates are added into the diet in the form of nutrient-dense, fiber-rich foods increasing to 25 g of Net Carbs per day during the first week. The carbohydrate content is further increased each week or every several weeks in 5-gram increments until weight loss ceases or begins to slow. At this point, the Net Carb prescription is reduced by 5 g. The individual remains at this level for a sustained, moderate weight loss, generally averaging one to two pounds per week.
Phase three is “Pre-Maintenance,” which transitions the individual from weight loss to weight maintenance by increasing daily carbohydrate intake in 10-gram increments every week for several weeks to maintain very gradual weight loss, generally half a pound a week. Once the goal weight is achieved, the individual remains at that carbohydrate intake level until body weight stabilizes for one month.
The final phase is referred to as “Lifetime Maintenance.” Emphasis is placed on sustainable lifestyle changes in order to maintain the lower weight. Individuals continue to eat the same variety of foods as in the last month of Pre-Maintenance while controlling carbohydrate intake to ensure weight maintenance. A slight increased intake of natural fats is necessary to maintain the lower weight since body fat is no longer the primary source of energy.
Over the years, the diet has evolved to emphasize healthy protein and fat choices from a variety of foods. Vegetables are included in every phase of the Atkins program including the most restrictive induction phase. As an individual progresses through the diet phases, ingestion of more vegetables along with low-glycemic fruits, nuts, seeds, whole grains, and legumes is encouraged. Later versions of the original Atkins Diet acknowledged that exercise is important for weight loss and maintenance as well as for achieving overall health benefits.
Benefits and complications
The benefit of the Atkins Diet is that it results in dramatic reduction in body weight and often with reversal of comorbidities, improvement of lipid profiles, and reduction or elimination of associated medications. The Atkins Diet has a very good safety profile with extremely low reported complications
There are some potential complications that should be considered, nonetheless. The effects of low-carbohydrate, high-protein diets on urinary stone formation have not been extensively studied, and there are conflicting results. There are some data to suggest that high-carbohydrate diets, especially from simple carbohydrates such as glucose or xylitol, result in an increase in calciuria.
Xylitol consumption has been associated with a rise in urinary excretion of phosphate and oxalate, which can promote the formation of calculi. A high sucrose intake was associated with an increased risk for kidney stones in individuals with no history of kidney stones in the Nurses’ Health Study. Sucrose has been shown to result in increases in serum insulin and urine calcium excretion. Although the data is limited, studies such as these would suggest that high-protein, low-carbohydrate diets are protective against renal stones.
One short-term study specifically addressed the effects of consumption of a high-protein, low-carbohydrate diet on kidney stone formation. This study showed a marked increase in the acid load to the kidney with an increased risk for stone formation and a decreased estimated calcium balance. Thus, the exact effects of high-protein, low-carbohydrate diets on nephrolithiasis remain unclear.
Overall, reported complications are low, not serious, and generally from a few select case reports. Nevertheless, there are certain groups of individuals who may require additional monitoring or slight modifications to the Atkins Diet plan. For example, individuals with compromised renal function should be closely monitored or placed on a modified regimen that would not adversely affect renal function. Individuals with gout who become symptomatic should be placed on the maintenance phase of the program.
Pregnant women and nursing mothers are advised to follow the maintenance phase of carbohydrate restriction, avoiding ketosis as a precaution. There is one reported case of ketoacidosis associated with a low-carbohydrate diet in a non-diabetic lactating woman. However, her estimated carbohydrate intake was less than 20 g per day for 10 days prior to admission to the hospital, an amount that is even less than what is typically prescribed in the induction phase
The diet has a very good safety profile. However, there are certain considerations that may influence the decision to embark on this dietary regimen. First, can you drastically reduce the carbohydrate and sugar in your diet including grains, fruit, and dairy products? The diet works by restricting grams of carbohydrates so the individual must be willing to calculate and keep track of the carbohydrate intake.