Dietary protein has shown to promote weight-loss efforts partly due its effects of enhanced post-meal satiety in comparison to carbohydrate or fat. To elucidate the mechanisms underlying this effect, several researchers have looked to the gut-endocrine system for answers since it is the source of potent hormone regulators of ingestive behaviors. For instance, peptide YY (PYY) is a gut hormone generally secreted in response to a meal to subsequently suppress appetite through the inhibition of Neuropeptide Y (NPY), a potent orexigenic (appetite stimulating) neurotransmitter. In this study, normal weight and obese human subjects demonstrated a greater release of PYY and more pronounced satiety following a high protein meal versus high carbohydrate or high fat meals. Interestingly, post-meal release of other apptetite regulators like leptin and GLP1 were not affected by macronutrient distribution (although other studies have shown greater GLP1 following protein intake). Thus, it appears that protein-mediated satiation is indeed mediated (at least in part for now) by gut hormone regulation of appetite, particularly via PYY. These findings, along with others, suggest that manipulating the release of endogenous satiety factors, such as PYY, through alteration of specific diet constituents could provide a rational strategy for weight loss or therapy for obesity. Also, I previously discussed evidence indicating greater basal PYY levels with higher intensity exercise training. Thus, when considering the practical applications of these findings collectively, higher intensity exercise and a high protein caloric restrictive diet may certianly be the optimum approach to weight loss. As I've emphasized before, the traditional focus of exercise and protein intake with respect to weight loss has been overly and fallaciously directed towards energy expenditure where in fact, much of the evidence demonstrates their benefits to be more so related to the control of energy intake.