No, it's not another fad diet for losing weight!
It's really a philosophy for healthy eating that's been around for thousands of years and was put into perspective about 70 years ago by the work of Weston A. Price (WAP). The idea is to eat foods that kept our ancestors healthy and to avoid highly processed and refined foods that are low in nutrients and high in harmful additives. Actually, many people do lose weight using this approach to eating, but the main goal is getting good nutrition for optimal health. Normalizing weight is a fringe benefit :)
Not all of the foods that our ancestors ate were equally healthy. Some foods confer greater health than others. That's what Weston Price studied in the 1920's and 1930's when he traveled around the world to document the native foods that people ate and their health. His conclusion was that the healthiest native diets included animal seafoods, organ meats, and/or dairy in their diet. These are the foods that have provided optimal nutrition for thousands of years. He found that when people abandoned the healthy diet of their ancestors for a more modern diet of refined flour and sugar and highly processed foods, their health suffered greatly.
Today we see a massive shift to highly processed foods in much of the world and a corresponding rise in poor health. Rates of obesity are increasing rapidly as people follow sadly misguided conventional dietary and health advice and are confused and misled by advertising for manufactured fake foods. When they get sick, they are given expensive drugs that often cause more health problems than they solve. It's time to get back to the foods that kept people healthy for thousands of years and shun the modern manufactured fake foods.
The Weston A. Price Foundation (WAPF) has been teaching the about the WAP approach to eating for about 10 years now and is a good source for health and diet information. My experience is that each of us has to discover which ancestral foods are best for us by trial and error. Not all traditional foods are best for everyone. Try them out and find the ones that work best for your health. Here's a WAPF video that discusses Price's teachings:
Some people have food sensitivities to even some traditional foods that others are able to tolerate. Read here for more information about food sensitivities. That's why it's important to find the traditional foods that work best for your own health.