These are the building blocks of our nutrition and called macronutrients. Getting the balance right is essential to be healthy and help achieve your training goals. You should never cut out any of these macronutrients from your diet, as you will end up with severe nutrient deficiencies long term.
So, how do you determine the right amount of macros for you? To keep things simple, we will use a basic equation which multiplies your minimal energy expenditure with your level of activity. Now, this page looks like a load of numbers but if you work your way slowly through it, its really not very difficult at all...
Firstly you need to determine how many calories you will use by doing nothing (your basal metabolic rate, or BMR). You can do this easily HERE, entering you age height and weight.
Once you have this number, can can determine your total daily calorie needs by useing the following calculations:
If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
If you are moderatetely active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
If you are very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
If you are extra active (very hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9
So, for example, my BMR is 1,287Kcals but I am very active, so my daily calorie intake would be 1287 x 1.725 = 2220Kcals. I also know this is true from the gadgets I use in training which tell me how many calories I burn during exercise each session. So its a pretty good indicator.
But how does this tell you how much fat, carbohydrate and protein you need?
Well, here is another calculation...You should intake roughly 0.3-0.4g of fat for each pound of body weight, 1 g of protein and the rest is carbohydrate.
Now, you also need to know that protein and carbohydrates both give 4Kcals per gram whilst fats give 9Kcals per gram.
This means, as 126lb in weight, I should be having126g protein (504Kcals), 38g fat (342Kcals) and 343g (1374Kcals) carbohydrate.
Now this is for someone who doesn't have any specific dietary needs such as elite athletes, body builders, and is relatively fit and healthy, but its a pretty good guide for the average person.
And remember vegetables and fruit all contain carbohydrate, so although you might think this is a lot of carbs (and we are constantly being told to "cut out the carbs"), they also contribute into this category, so load it up!