It means that the variety of foods does not bring you to success, not now and not even in the future. In comparison in our ancestors who used to eat only primitive foods, we are suffering now from overweight, but our previous generations were slim and fit.
This way to loose weight seems very realistic and hopeful, taking into account people who have gained benefits from such a healthy eating. Some of then needed several months to see visual results, others tried longer - for half a year. But, nevertheless, this diet works, that has been already proved by thousands of people from different countries. It's one more strong point is that you can start it in every age, even if you are in your late 60s.