We looked into Fat Loss 4 Idiots (FL4I) at the request of a Diet Inn member.
Summary: Give FL4I money. Follow the FL4I rules, most of which are simple common sense. Follow the FL4I online meal planner. Supposedly lose almost a pound a day.
Pros: Paying attention to your diet and trying any change may make you more aware of what you eat. Some of the FL4I rules such as drink more water and eat more meals at home may help.
Cons: Your hard earned money is spent for dubious advice.
Bottom line: Avoid.