The Atkins Diet is also a low carbs, high protein diet. It was invented by Dr. Robert Atkins in the early 70s. The South Beach Diet was conceived having as a departure point the Atkins diet, but essentially improved.

Short survey of South Beach Diet vs Atkins Diet

• Both diets work on the notion that weight gain is caused by the way the body reacts to carbs, particularly processed carbs (bread, potatoes, pasta), and not by fat intake or food portions.
• Both diets have the disadvantage of not being proven long term effective, moreover, the American Heart Association's most serious claim against diets such as Atkins and South Beach is that, on the long run, they may increase the number of potential health risks such as osteoporosis, stroke, coronary heart disease, kidney stones, liver disorders and diabetes.
• In South Beach Diet Phase 1, the basic principle is the same as in Atkins: carbs intake restriction. This lowers insulin levels and makes the body produce ketones, which also have the effect of suppressing appetite. The two diets share similarities up to a point: the carbs lowering is not as drastic in South Beach Diet. Dr. Agatston states that the carbs level should be kept at a safe level by complex carbs consumption, so that ketosis and its unpleasant side effects are avoided (dizziness, nausea, headaches, bad breath and faintness).
• Both diets involve gradual re-introduction of some carbs after a couple of weeks, thus providing a maintenance program, with the carbs intake much lower than the customary one.

Allowed foods

Atkins Diet

• Promotes eating all sorts of protein-providing foods, especially of animal origin and going so far with the carbs intake restriction that it allows very little foods of vegetable origin. This is a shortcoming, as it encourages the intake of saturated fat, overlooking the benefits offered by vegetables and fruit and cutting out many valuable nutrients by its restrictive nature. At the same time, it allows no choice for vegetarians.

South Beach Diet

• From this point of view, it is more permissive and more balanced, allowing consumption of foods from all main food groups after the first phase.
• South Beach Diet has a major advantage over Atkins — it promotes healthy foods — healthy unsaturated fats (monosaturated olive oil), that have the effect of lowering bad cholesterol, complex, low GI carbs, that help insulin level regulation.
• It also allows more cheats occasionally (sweets for example).
• More vegetables are allowed as well as breads and grains in moderate amounts. It even has a vegan version.

Being a very low carbohydrate level diet, Atkins Diet is also very low in fibre, thiamin, folate, vitamins A, E, B6, calcium, magnesium, iron, potassium and antioxidant phytochemicals. Such a diet is likely to increase the risk of cancer, heart disease, diabetes and osteoporosis from the side effect of increased calcium excretion.

Although a low carb diet, South Beach Diet covers these aspects better and recommends more foods that contain these important nutrients. Nevertheless, a calcium and multivitamin supplement is recommended even with South Beach.

Another major difference between the two diets is that the South Beach Diet recommends moderation (implying lower caloric intake) while Atkins does not even suggest it.

The only advantage that Atkins has over South Beach would be that in Atkins the weight loss is bigger and faster. But this “advantage” can be dangerous for health, as rapid and massive weight loss cannot be healthy when occurring in a very short time and with the cost of depriving the body of valuable vital nutrients — vitamins, minerals etc.