The newest study, presented at a meeting of European cardiologists in August, looked at a U.S. sample of nearly 25,000 people. It found that the low-carb eaters had a 32% higher chance of dying from any cause during a follow-up of over 6 years. The risk of death from heart disease, when looked at separately, was 51% higher, stroke, 50%, and cancer, 35%. They evaluated other studies to confirm their findings.
The theory is our bodies were designed, and still optimized, to eat what our Paleolithic ancestors ate. Like your hunger-gatherer forefathers, on Paleo you get all the meat from wild animals and unlimited fruits and vegetables you can eat. But no starchy vegetables (like potatoes), no legumes (like lentils or beans), no wheat, and no grains (like quinoa or corn) because those plants were invented by human beings during the agricultural revolution after our Paleolithic ancestors left the planet. You get one cheat day where you can eat whatever you want (“Occasional cheating and digressions may be just what you need to help you stick to the diet.”) No oil because it puts omega 6 and omega 3 ratios out of whack which should never exceed 2:1, except olive oil if you must. Dairy is also prohibited. And meat must come from animals that weren’t fed grains (like corn) because grains lead to inflammation and increased fat.
Fattening cattle with corn changes the lipid balance and is clearly not the natural diet for a grass eating cow. In Simple change in cattle diets could cut E. coli infection researchers have found that when cattle were fed hay or grass for just five days before slaughter, much less E. Coli cells were present in the animal's feces and virtually all surviving E. coli bacteria were not acid-resistant and were killed by human stomach acid.
So what does the science say about the paleo diet? Some research suggests that the health claims hold truth. A review analyzed four randomized, controlled trials with 159 participants, and researchers found that the paleo diet led to more short-term improvements in some risk factors for chronic disease (including waist circumference and fasting blood sugar) compared with other control diets. (4)