I've gained 30lbs this year by eating a lot and training a lot. Now I want to put on another 20lbs by the end of the year. To be sure that I'm not increasing my body fat percentage, I'm trying to plan meals carefully.
When I enter my weight, age, and activity level into some of these online macro calculators, it spits out different amounts of macros depending on whether or not I want to gain or maintain:
Gain: 149g protein 113g fats 445g carbs ~52% total calories: 3,389 Maintain: 165g protein 99g fat 354g carbs ~47% total calories: 2,965
I understand the general role of carbs in providing energy, and protein in building muscle... but I'm curious about:
1) Why the ratios change a little between Gain vs Maintain
2) Are these amounts determined through objective, scientific means? Or is this method just a "best guess" because of the debates over carbs vs fat / the meaning of a "calorie" / etc?