When it comes to body composition changes, whether it be gaining muscle, losing body fat, or a total recomposition, the most important macronutrient to keep in check is protein. Right behind total calorie intake, protein will better determine the type of bodyweight you gain or lose.
Whether you gain muscle or fat, whether you lose muscle or fat.
The typical American diet sees less than 80g of protein per day (often below 50g) which can lead to becoming skinny-fat (softer, less cut and tone look) when losing weight, or frustrating plateaus when trying to gain lean body mass.
When trying to change your composition keeping protein higher will result in better preserving lean body mass, feeling more satiated on a diet, and finishing in a more defined and athletic look.
This calculator will help you get a better estimation of how much protein you should consume day-to-day.