“Instead, it embraces foods that could be hunted or gathered: meat, fish, poultry, eggs, vegetables, and fruits,” says Erin Dolinski, RD, a clinical dietitian specialist in Royal Oak, Michigan. Swapping a spaghetti-and-meatballs dinner for a plate that’s loaded with veggies and a lean piece of protein may not be easy, but it could be beneficial to your health. Mark Hyman, MD, the author of Food: What the Heck Should I Eat? and the director of the Cleveland Clinic’s Center for Functional Medicine, says these “detox symptoms” usually last seven days. “After about a week, [my patients] start to feel way more energized and clearheaded, and they start to feel good,” he says. “And as a bonus, the pounds come off too.” A small study found that people who followed the paleo diet lost just over five pounds after three weeks. They also saw a 0.5-centimeter decrease in their waist circumference as well as improvements to their systolic blood pressure. (1) Systolic blood pressure refers to the pressure in your blood vessels when your heart is beating. (2) Other research found that switching to a paleo diet led to short-term improvements in five components of metabolic syndrome (a risk factor for cardiovascular disease): waist circumference, triglyceride levels, blood pressure, HDL cholesterol, and fasting blood sugar. (3,4) “Cutting out whole food groups, which is what the paleo diet does, results in a very restrictive diet, which is difficult to adhere to long term,” Dolinski says. “The key to good nutrition is moderation, variety, and balance, and the paleo diet lacks variety and balance.” Another barrier is that the diet can be expensive. Research suggests it can be 10 percent more costly than a diet with similar nutritional value. (7) By cutting out entire food groups on the paleo diet, you may also miss out on key nutrients. Take dairy products like cheese, yogurt, and milk, for example. These can be great sources of calcium and vitamin D, both of which are critical to bone health, Dolinski says. One study found that people who followed a paleo diet had just 50 percent of the recommended dietary intake of calcium. (1) That’s why nutrient deficiencies are one health risk of the paleo diet. Paleo dieters need to be careful about the types of meat they use to fill their plate. Red meat is high in saturated fat, which can raise blood cholesterol levels and increase the risk of heart disease and stroke. (8) Red meat should be consumed only in moderation, with no more than 13 grams of saturated fat per day if you’re following a 2,000-calorie-per-day diet. (8) (If you’re eating fewer calories, your saturated fat intake should be less.) That limit is easy to hit — a 3-ounce steak and a tablespoon of butter will put you over. Eating too much red meat can also be harmful to the kidneys, which play a role in metabolizing protein. One study found that replacing one serving of red meat with another type of protein — like chicken or seafood — can reduce the risk of end-stage kidney disease by 62 percent. (9)