This diet cuts out all glucose-based foods, such as:
Sugars, sweets and cakes
Sugary and alcoholic drinks
Carbohydrates (pasta, rice, potatoes, bread...)
Pulses (lentils, beans, peas, grains...)
All fruit
Milk

However, you can eat butter, cream, yoghurt and cheese.
Green vegetables are limited to 50grs per meal.
You can eat as much as you like of everything else, so most meals on this diet will be made up of meat, fish, eggs and cheese. There are no restrictions on mayonnaise, butter and oils either.

Atkins in brief:

Eat:
Meat, both red and white
All fish and seafood
Cooked eggs
All cheeses, apart from diet, or 'light' cheese, which contain glucides
Avoid:
Green and fibrous vegetables
Lettuce and other salad leaves
Herbs and spices
Fats, apart from margarine, mayonnaise, butter and creme fraiche.

With no carbs or sugars, the body not only burns fat for energy, but also muscle, leading to mental and physical fatigue.
The lack of fruit and vegetables can lead to vitamin, mineral and fibre deficiencies.
A high fat intake will push up your cholesterol level, which can cause heart disease.
As soon as you finish the diet and start eating carbs again, the weight will come back on as quickly as it dropped off.