Back to the topic, let's compare the nutritional components of whole eggs, protein and yolk:
Egg 143kcal/ 100g contains 13g protein 10g fat.
Protein 48 kcal/100g contains 1 1g protein 0g fat.
Egg yolk 3 17 kcal/100g contains16g protein 27g fat.
Obviously, the calories of egg yolk are much higher than those of egg white. All the fat in eggs comes from yolk, and low protein, low calorie, low fat and high protein are ideal supplementary sources for protein. If you eat egg yolk together, you will consume too much fat (and cholesterol), which will affect fat loss.
Someone mentioned in the answer that this practice is wasteful. Although it is a pity to throw away the egg yolk, personally, eating it is a waste. Too much egg yolk intake will hinder us from gaining muscle and losing fat, and no amount of exercise will help. From this perspective, choosing to eat it is a waste of sweat from our fitness.