Nothing like some nutritional pseudo-science in my manga. You can eat fat only or sugar only and lose fat. It won't be healthy but you can. Also that pfc chart is stupid for losing fat - protein is more satiating and takes more energy to be processed than carbohydrates. Meaning you can eat more of it compared to other stuff for the same energy. So this should be rather 13-20% fat, 20-30% carbs, 50-65% protein and it would be a lot easier to feel satiated even when eating less calories.