Two popular diets for weight loss that emphasize protein are the Paleo diet and the Dukan diet. Proponents of high-protein diets observe that protein has fewer calories per gram and takes more energy to metabolize than fat or carbohydrates, which leads to lower calorie intake and increased metabolism.
The Paleo diet's name refers to the Paleolithic period of more than 10,000 years ago, when people were hunters and gatherers. Advocates of the diet say certain technologies, such as agriculture and dairy farming, have increased the prevalence of carbohydrates and calorie-dense foods, which has led to the problem of excess weight. The diet calls for avoiding all foods that were not available in prehistoric times.