Originally Posted by
link0
The percentage refers to macros (macronutrient ratios), which is a commonly used marker in the nutritional world. Percentage of nutrients to lean body mass is extremely important. Optimal absolute intake of macronutrients is obviously different for a 150lb man vs a 250lb man.
No one uses percentages anymore, because it's outdated and irrelevant. All that matters is the absolute intake or how it relates to body weight or lean body mass. Protein recommendations are given in g/lb of LBM or BW, and the same goes for fat. Carbs don't really have an optimal intake.
Someone already suggested Lyle McDonald above, so read this article of his on why setting up a diet based on macronutrient ratios is a mistake:
Diet Percentages: Part 2 : Bodyrecomposition.