In nutrition, as in training, there are no “secret formulas” with miraculous results. However, there are some general rules that you can follow based on scientific knowledge and common sense. 

The following are notes of a general nature. For more personalized and detailed information, contact a dietician with experience in sports nutrition. 

- Maintain balanced nutrition - 
Try to observe this rule for every meal you eat: each meal must have a proper amount of all the main nutrients: carbohydrates, protein and fat. 
Carbohydrates must prevail (50-60% of the total calories) over protein and fat (20-25% of the total calories, each). 

Try to have a daily protein intake of about 1.0 – 1.5 g/kg of your body weight. 
For example, if your body weight is 70 kg, you should take 70-100 g of protein per day. 
If you are training in altitude, you should increase the daily protein intake by 2.0 g/kg. 

Generally, fresh meat and fish have a protein amount of about 20% of their weight. For example, 200 g of meat contains about 40 g of protein and an egg contains approximately 8-10 g of protein. 
Cereal, legumes, bread and pasta have a protein amount of about 8-12% of their weight. 1liter of milk (either cow or soy) contains 35 g of protein. Cheese has a variable amount of protein, but remember it is also high in fat.
For a better source of fat, favor vegetable oils (i.e. olive oil). 

- Avoid excessively big meals - 
Try to subdivide your daily caloric intake into 3 main meals, each of them of approximately 600-1000 Kcal. You can even have 1 or 2 small snacks during the day (100-200 Kcal each). 

- Limit your simple sugars intake - 
Try to have complex sugars such as pasta, rice, cereal, potatoes or vegetables instead. 

Remember that your daily carbohydrates requirement fluctuates between 200 and 400 g, according to your training regiment.

 

Avoid, or at least limit your alcohol consumption. 
Check your body weight frequently and consistently. Make sure you use a reliable scale (same scale every day) and always weigh yourself under the same conditions (in the morning, before breakfast, wearing the same clothes): it really is the easiest way to check whether you are following a proper diet or not. 

If you have to lose weight, avoid losing it too quickly: try to lose 0.5 kg per week instead. Never lose more than 1 kg per week.