The Atkins diet is when a person is encouraged to eat protein and fat instead of carbohydrate. This will enabled the body to burn fat for energy instead of burning carbohydrate for energy and leaving fat stored away. The body burn carbohydrate first and then fat. Carbohydrate can turn into sugar if it's not used up by the body. This is why people have diabetes. They have too much sugar in their bloodstream. When a person have a low carbohydrate level in their body, the body go into ketosis by burning fat off for energy. You will lose fat and lose weight when it's burn for energy instead of carbohydrate. This diet works for those that understand why we need to eat less carbohydrates. Carbohydrate is sugar and sugar will be converted to fat by insulin if your cells are not using it right away. A lot of time, we already have so much fat store away that we don't need to use the sugar right away in our bloodstream.

A person on the Atkins diet should eat less than 40mg of carbohydrate per day. Physical activity along with dieting can help a person lose weight faster. Excercising can help the ketosis process. People can also take vitamins to replace the nutrients that they're not getting from carbohydrates.

Food not allowed

Sugar, milk, white rice, white flour, and most fruits and vegetables

Food allowed

Rich meat, eggs, fish, tuna, cheese and they reduce your appetite

There're some down side to this diet. You don't get enough fruits and vegetables which contains a lot of nutrients that are healthy for you. You also consume high fat and protein which is not good for the heart. You're also consuming a lot of calories because the diet doesn't restrict you to calories. There's no research that proves that the Atkins diet works but it make sense to cut down on carbohydrate since carbohydrate is essentially fat if it's not used up by the body right away.

Source: http://www.webmd.com/diet/atkins-diet-what-it-is