The Surprising Side Effect Of The Keto Diet That We Need To Talk About

If you've been considering trying a low-carb diet, whether it's paleo or the of-the-moment ketogenic diet, you need to read this first. A new study1 found that replacing carbs with animal fats and protein, as is often the case with low-carb diets, is linked to a shorter life span.

Researchers studied 15,428 adults who self-reported on dietary intake over a period of 25 years. Based on carbohydrate intake (and no other factors), they found that people whose diet was comprised of less than 30 percent carbs died three years earlier than those who ate higher amounts of carbohydrates, with an average life span of 79.1 years versus 82 years, respectively.

That's not the whole story, though. The authors of the study then homed in on the type of carbs consumed in the various diets—and this is where things got interesting. The risk of early death went up for dieters who consumed large amounts of animal-based protein and went down for low-carb eaters who consumed more plant-based foods like nuts and vegetables.

The study, of course, has its various faults. Participants self-reported what they consumed, and researchers only checked in on them every six years. When researchers conducted a meta-analysis of other studies on low-carb diets and mortality, however, they found similar results. Like many studies, there's no way to tell whether the results are correlative or causative.