Paleo Diet Short- and Long-Term Effects

The paleo diet has been one of the trendiest weight loss plans out there today, but it’s rooted in our ancestors’ eating habits from tens of thousands of years ago. The diet rejects many of the food groups that make up the typical American diet — including grains, dairy, sugar, and legumes.

“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.

If you’re considering the paleo diet, the first challenge you’ll likely encounter will be overcoming waning energy levels. (Have a tendency to get hangry? Consider yourself warned.) Without energy-rich carbs, you may feel excessively tired and in a bad mood, says Adrienne Youdim, MD, an associate clinical professor of medicine at the University of California David Geffen School of Medicine in Los Angeles. Those crummy feelings may be even more extreme if you’re used to eating carb-heavy meals filled with bread and pasta. Cue the temptation to quit!

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)

If you have weight to lose, you may or may not be able to keep weight off in the long term on the paleo diet. One study examined the effects of the diet on postmenopausal women with obesity after 6, 12, 18, and 24 months. The paleo group had lost significantly more weight compared with the control group (which followed a low-fat, high-carb diet) at the 6-month mark, but those results didn’t carry over after 24 months. At the end of the two-year study, however, the participants who went paleo lost more fat and saw greater improvement to abdominal obesity and triglyceride levels. (5)

One of the catches of this approach is you’ve got to stick to a paleo menu to see improvements. That seems obvious, but many people find it difficult to stay on track because the approach is restrictive and is not always conducive to traveling or eating out. Some experts say it’s not an effective strategy for sustained weight loss for that reason. (6)

“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)

The paleo diet has been linked to weight loss and improvements to blood pressure and lipid profiles. But most research has been small in scope and conducted over a short period, so it’s too soon to say conclusively what long-term effects you can expect after following the diet for years. (7)