Version July 2025
ANSWER —
Incorrect.
The Atkins Diet is a very low-carbohydrate ketogenic diet, similar in principle to the South Beach Diet. Since its introduction decades ago, the justification and marketing of the diet have changed, although the basic principle of carbohydrate restriction is unchanged. In earlier iterations, it was said that controlled studies were impossible in nutrition. Now, controlled studies that are purported to support the Atkins Diet are presented on the Atkins website. (See "Obesity in adults: Dietary therapy", section on 'Low-carbohydrate diets'.)
Whereas the South Beach Diet has three phases, the Atkins Diet (as initially described) has four [1]. Phase 1 (Induction) limits carbohydrates to 20 grams per day for at least two weeks, while "you satisfy your appetite with fish, poultry, eggs, beef, and other foods high in protein and good fats, such as olive oil." In Phase 2 (Ongoing Weight Loss), you are advised to add back "nutrient-rich carbohydrates… by adding just 5 grams of Net Carbs [total carbohydrate content minus the fiber content] per day in weekly increments until weight loss ceases… for most people that amount is somewhere between 40 and 60 grams daily…"
In Phase 3 (Pre-Maintenance), the reader is advised to "add another 10 grams of daily Net Carbs to your program - or treat yourself to an extra 20 to 30 grams of nutrient-dense foods twice a week - so long as you continue to lose. If your weight loss stops, cut back 5 or 10 grams until you resume gradual weight loss…" In Phase 4 (Lifetime Maintenance), "you can start enjoying an even wider range of delicious foods… Most people find that they can maintain their weight by consuming somewhere between 45 and 100 grams of Net Carbs a day…" The Atkins diet does not restrict eggs, butter, and other high-fat foods.
The current version of the Atkins Diet has the same four phases with modifications in the quantity of Net Carbs in each phase. The Atkins Diet now offers a choice that provides 20, 40, or 100 grams of Net Carbs a day in Phase 1.
The Atkins Diet should not be used in patients with type 2 diabetes, especially those who are treated with insulin or an insulin secretagogue. In particular, the use of the Phase 1 diet should be discouraged in patients on insulin or insulin secretogogues as it is difficult to predict its effect on the dose of these agents. The sudden and marked reductions in carbohydrate intake will result in corresponding decreases in insulin requirement or dose requirement for insulin secretagogues. In the insulin-treated patient with type 2 diabetes who begins Phase 1, hypoglycemic reactions, sometimes severe, may occur. Conversely, the conversion from Phase 1 to subsequent phases will be accompanied by hyperglycemia in a previously well-managed patient and will usually necessitate an increase in the doses of insulin or other diabetes medications.
In general, the value of a very low-carbohydrate or ketogenic diet is questionable. When used for a brief period, as such diets have been in the past, patients almost invariably regain the weight that has been lost on the diet when they return to the previous diet. Very low-carbohydrate diets are not recommended for long-term use [2] (see "Medical nutrition therapy for type 2 diabetes mellitus"). The long-term effects of very low-carbohydrate or ketogenic diets are not known. Although they may produce short-term weight loss, the long-term effect on weight loss is similar to that from low-fat diets [3,4]. The long-term impact on cardiovascular risk factors or outcomes is not known.
The use of a very low-carbohydrate diet in adults without diabetes as part of a long-term dietary program such as the Atkins Diet may have certain advantages; in particular, the enhanced motivation that often occurs when short-term weight loss is achieved. However, in patients on insulin or an insulin secretagogue, the risks of altered glycemic management and especially of hypoglycemia outweigh the putative benefits.
In a patient with type 2 diabetes who is not on these medications, the use of a ketogenic diet is also unwise. In a patient without diabetes, ketosis is a measure of the lipolysis and ketogenesis that occur physiologically in response to a markedly reduced carbohydrate intake and decreased endogenous insulin secretion. In a patient with diabetes, ketosis means inadequate diabetes management until proven otherwise.
Return to the beginning to try again. (See "Interactive diabetes case 18: A 61-year-old patient with type 2 diabetes and a recent change in diet (medical nutrition therapy)".)
