Paleo diet proponents avoid grains, legumes, dairy products, salt, sugar and oil. Instead, they base their meals around meat, fish, vegetables, roots and nuts. Unlike the raw food diet, those following this diet can cook their foods. This high-protein diet was first popularized in the 1970s by gastroenterologist Walter L. Voegtlin who claimed that human genetics have not changed much since the dawn of time, so it makes sense to eat what our ancestors ate to avoid modern diseases like obesity, diabetes, heart disease and high blood pressure.

The American Dietetic Association classifies the paleo diet as a fad diet.

"The caveman diet may have some quick-fix weight-loss effects, but the diet leaves out healthful components of well-balanced eating such as heart-healthy, cholesterol-lowering whole grains, breads and cereals, beans and legumes, and calcium-rich dairy products," says Marissa Lippert, R.D., a New York City nutritionist from Nourish Nutrition Counseling & Communications. "As our agricultural system evolved over thousands of years, so has our bodies' nutrition needs. If we exclude entire nutrient categories from our diet, our energy levels, cravings and general health can be impacted."

If you want to stay healthy and lose weight, the majority of health professionals agree that a reduced-calorie diet that a variety of foods is the healthiest approach.