Everyone says I should eat chicken breast when dieting, but why exactly is that?

From a biological perspective, protein maintains muscle mass, which prevents the basal metabolic rate from dropping. A stable metabolism ensures that your body burns energy more efficiently even when consuming the same amount of calories. However, it is important to consider this from the perspective of Traditional Korean Medicine (TKM). No matter how high the quality of the protein, it is ineffective if your digestive and absorptive functions are impaired. In TKM, this condition is referred to as 'Spleen Deficiency' (Bi-heo, 脾虛). When the Spleen's function is weak, proteins are not converted into energy and instead stagnate in the intestines, creating an environment where 'Phlegm-Fluid' (Dameum, 痰飮)—or metabolic waste—accumulates. Consequently, if undigested protein residues obstruct the flow of energy and blood, similar to the formation of 'Blood Stasis' (Eohyeol, 瘀血), it can lead to edema (swelling) and chronic fatigue. Therefore, rather than focusing solely on 'what to eat,' it is more critical to determine if your body is 'prepared to absorb' those nutrients. For the most efficient results, I recommend adjusting your protein intake based on your current digestive health and combining your diet with TKM treatments designed to boost overall metabolic function.