How is one determining whether a diet works or it doesn't work? I hear many times people say "I tired this diet and it didn't work for me". How does one determine that? Don't you have to wait 30 years or so to see if you haven't developed some disease that you would normally expect to develop? There is no miracle after a month or a year. So why so many claim this or that diet is not working for them after trying to eat different for 2 months or half a year or two? What's the timeframe criteria?