The study of low-carb diets has centered on weight loss in obese and overweight people as well as patients with or at risk for cardiometabolic diseases such as type 2 diabetes and nonalcoholic fatty liver disease. Ketogenic diets have also been used for seizure disorders and more recently have found use in the athletic population as an alternative fuel for performance and health.
Adoption of the Paleolithic diet assumes that modern humans can reproduce the hunter-gatherer diet. Molecular biologist Marion Nestle argues that "knowledge of the relative proportions of animal and plant foods in the diets of early humans is circumstantial, incomplete, and debatable and that there are insufficient data to identify the composition of a genetically determined optimal diet. The evidence related to Paleolithic diets is best interpreted as supporting the idea that diets based largely on plant foods promote health and longevity, at least under conditions of food abundance and physical activity." Ideas about Paleolithic diet and nutrition are at best hypothetical.
Paleo eating requires a lot of planning, prep time, and mental resolve. For instance, eating out on the diet isn't as simple as ordering chicken and a salad. Think: In what oil was the chicken cooked? Did any of the salad toppings come processed, canned, or packaged? "As with every elimination diet, it's just not doable long term," Dr. Ochner says. While weight loss is far from the sole purpose of eating paleo, going on and off of the diet can lead to big weight swings. Any yo-yo diet starts in weight loss from both muscle and fat, and usually ends with weight gain of all fat, which contributes to a slower metabolism and increased insulin resistance.
You may lose weight on the Paleo Diet. If you build a “calorie deficit” into your Paleo plan – eating fewer calories than your daily recommended max or burning off extra by exercising – you should shed some pounds. How quickly and whether you keep them off is up to you. A 2015 review in the Journal of Gastrointestinal Liver Diseases concluded that a Paleo-esque diet “might be an acceptable antidote to the unhealthy Western diet, but only unequivocal results from randomized controlled trials or meta-analyses will support this hypothesis.” On that, we’re still waiting. In the meantime, here’s what has been found about the diet and others like it: