Dietary strategies that can help reduce hunger and promote fullness are beneficial for weight control, since these are major limiting factors for success. High-protein (HP) diets, specifically those that maintain the absolute number of grams ingested, while reducing energy, are a popular strategy for weight loss (WL) due to the effects of protein-induced satiety to control hunger. Nonetheless, both the safety and efficacy of HP WL diets have been questioned, particularly in combination with low-carbohydrate advice. Nonetheless, for short-to-medium-term intervention studies (over several months), increasing the energetic contribution of protein does appear effective. The effects of HP diets on appetite, bone health, renal function, blood pressure, cardiovascular bio-markers, antioxidant status, gut health and psychological function are discussed. Further research is warranted to validate the physiological effects of HP diets over longer periods of time, including studies that modify the quality of macronutrients (i.e. the type of carbohydrate, fat and protein) and the interaction with other interventions (e.g. exercise and dietary supplements).