The Paleo diet attempts to model what would have been eaten by humans during the Paleolithic era, also known as the prehistoric stone age of human development. This diet includes meats, fish, fruits, vegetables, nuts, and seeds—foods that presumably would have been obtained through hunting and gathering. It omits legumes, grains, dairy, refined sugar, low–calorie sweeteners, and “processed” foods.
Paleo proponents argue that the technological changes that came about with farming and other more advanced food production methods—like the addition of grains, dairy, and legumes to the diet—outpaced our body’s ability to adapt to this new way of eating. This incompatibility, they attest, has contributed to many diet-related diseases we see today.
This hypothesis has some scientific flaws. For example, recent research from the National Academy of Sciences Proceedings demonstrates that ancient humans may have begun eating grasses and cereals before the Paleolithic era began. Hence, the idea that no grains were eaten in that time period is most likely an exaggeration. Additional research shows that beans and legumes were eaten in the Paleolithic era as well.
Regardless of whether the idea behind this eating style is true, the Paleo diet has been adopted by many people seeking to lose weight and improve their health. But what does the research say?
The Paleo Diet and your health
A meta-analysis of 11 randomized controlled studies examined the relationship between adopting a Paleo diet and changes in anthropometric markers like weight, body mass index, and waist circumference. Following a Paleo diet was related to statistically significant weight loss (about –3.5 kilograms (kg), or –7.7 pounds), BMI decrease (–1.09 kg/meters2), and weight circumference reduction (–2.46 centimeters) as compared to diets based on standard dietary recommendations for adults. However, the authors noted that more randomized clinical studies with larger populations and duration are necessary to prove the health benefits of following the Paleo diet.
There is some evidence supporting the beneficial effects of a Paleo diet on cardiovascular disease risk factors. A meta-analysis of eight studies found that a Paleo diet reduced body weight, waist circumference, body fat percentage, blood pressure, and total cholesterol (lowered LDL and raised HDL). Though the meta-analysis found positive effects stemming from the Paleo diet, the authors also noted that the evidence is not conclusive, and more well-designed trials are needed.
Blood Sugar and Type 2 Diabetes
Since the Paleo diet limits carbohydrates, dairy, legumes, and refined sugar, it’s no surprise that it has demonstrated reductions in blood sugar and blood glucose control markers in a few randomized controlled trials. These studies were short and had small sample sizes, so it’s unknown if following a Paleo diet would continue to show positive results over a long period of time. Nevertheless, one study showed that people on Paleo had lower hemoglobin A1C (a marker of blood glucose status) levels compared to when they were not on Paleo. Another more recent systematic review and meta-analysis found that following a Paleo diet resulted in lower fasting blood sugar than a control diet that did not exclude grains, legumes, or dairy.
Overall, studies done exclusively on the Paleo diet’s effects on chronic diseases and body weight are small and limited in duration, though some have demonstrated potential positive effects.
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