Make sure you eat only complex carb's, or those carbs that are in their natural state, as refined carb's are disease-forming.
How many grams of carb's per day to be anabolic?
There are those who would argue against 80% carb's 10% protein and 10% fat 80/10/10 such as Mercola, as he goes along with the Nutritional Typing concept: one mans (sorry womans) food is another mans poison as it were.
This could be a hornets nest, as there are just so many opinions on what exactly is the right type of diet.
Rather than count calories (which I have never needed to do or even seen the need to do) I would just eat according to appetite: no more and no less.
After a 21 day fast you will be in an anabolic state anyway and where any useful nutrition will go towards that end.
I favor the plant-based approach to diet and for a number of reasons, which I am not going to go into here.
Suffice to say that the bodys main fuel source (when not fasting) is glucose and glucose derived from carbohydrates as the main fuel for everyday body functions, including the Brain.
Glucose is also the main source of fuel for the working muscles and not only stored there but released into the bloodstream when energy is required.
To the point..............
Anabolism: the building up of body cells and substances from nutrients requires energy, and is much more effective if the energy required to digest food, followed by the energy needed for catabolism is at its minimum.
The food that demands the LEAST amount of energy in digestion is fruit, as this is predigested by Nature, and this will allow more energy to be made available in both the catabolic and anabolic processes.
I would forget the calorie-counting (exclusively for weightwatchers-clubs who are attempting to extract the contents of your purse) and weight per gram of foodstuffs, as this is mostly irrelevant.
Put another way, if you lose weight then your calorie intake is not sufficient, whereas if you increase weight then you are consuming too many calories for the expenditure of calories on a daily basis.
Dr. Fuhrman created The Health Equation: H=N/C or Health = Nutrients/Calories. A low calorie but nutrient dense diet no less.