The Atkins diet is based on the idea that in the absence of carbohydrates the body will primarily rely on Ketones for energy production. Only 2 types of nutrients cross the blood-brain barrier, that is Glucose (in all carbs), or Ketones (which are produced during a low carb diet).
In a typical Atkins diet of 40% protein, 20% carbs, and 40% fat, ketones are formed from protein (endogenous and exogenous ie. from body muscle or food), or fat. Thus, the idea is that fat loss is obtained. Typically this type of diet is effective for short term fat loss, but the consequence is also increased muscle loss.
Ideally, The diet to be effective would require much protein. I would say 50%+ protein, and the total carbs would need to be below 100g per day (for use by the brain and in the liver). The fat would be used to provide energy.
However, as glycogen stores are diminshed, the intensity of training would perhaps also suffer. It is not possible to obtain supra-physiological levels of muscle glycogen (the body's primary source of energy for muscle contraction). This would likely limit the capacity to build muscle, not only because there is less glycogen, but also water in muscles. Hydration is a potent stimulator of muscle anabolism.
Thanks to the good man Matheen for the link, as you can find more information about low carb diets on the site.
It is very difficult for veggies to follow low carb diets unless they take exogenous protein exclusively. Ie. nothing but protein shakes and nuts. It takes a few weeks to become Ketone adapted, and a gradual reduction is necessary. Many believe that carb ups are necessary to overcome the glycogen loss. This means taking 500g of carbs on non-workout days for example. But I believe this is futile, as research suggests carbs go straight to muscle only when taken with exercise.
So
- protein shakes, nuts, protein shakes, etc. read the numbers to get a 50/20/30 ratio, keeping in mind carbs need to be below 100, so that would be 250g protein, 100gcarbs, 150g fats for 1000 + 400 + 1350cals for a total of 2750kcal per day. If your energy needs are higher, the extra must come from protein exclusively.
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