My Issues with the above...
Strict limitations- Only limitation should be to stick to whole, natural foods.
Specific period of time- Your entire life. Period.
Intentions of weight loss and/or improved health- A whole, natural diet and lifestyle will provide you with a healthy weight and body.
They go back to the way they were eating prior- Well, duh, that's what got you in trouble in the first place!
As defined by the all telling source of Wikipedia, "In nutrition, diet is the sum of food consumed by a person or other organism." This is how all American's should define the term. A diet should not be though of as restrictive and short term, it should be thought of as the summation of the foods you eat to provide you with the correct nourishment to lead a healthy life.
That being said, eating a diet of whole foods does just that. The only things it restricts are foods that are not, well, food. Stick to what was recently alive and will perish quickly, is in whole form as found in nature, and our earliest ancestors had access to (because those are the foods our bodies will digest best since they have been exposed to them the longest). Granted, our ancestors may not have prepared the foods the same way we do, but point being is that we are eating what they ate. What our bodies known. When you start to introduce things our bodies are not familiar with, problems arise.
Modern agriculture and cultivation of grains and legumes occured around 10,000 years ago. Quite a bit of time, yes, which is probably why most people can survive (not thrive) on them. We certainly have acquired some sort of tolerance for them. However, when you look at the common severe allergies people suffer from today, they are largely based upon grain products: corn, wheat, soy, oats...
Food Allergy Buddy™ allows you to choose which food allergies you have to be printed on a card you can bring to school, restaurants, where ever needed so who ever is preparing foods can avoid what you are allergic to (which would be a non-issue for places that feature a whole foods menu). 50% of these choices are from cereal grains. If you add in the dairy, peanuts, and potatoes, over 60% of these choices would not have been consumed by our earliest ancestors.
Personally, I do not need much more evidence. But, if you insist, check out Mark's Daily Apple and his plethora of posts on the Primal Blueprint, the basic inspiration for my lifestyle transformation. Especially his Definitive Guides on the Primal Blueprint, Eating Plan, and Insulin, Blood Sugar, and Type 2 Diabetes. Another great source of information is from Robb Wolf, a former research biochemist who is a true life story of how the Paleo Diet basically saved his life. Check out his FAQs on the "Paleo Solution". From these two sites, feel free to explore the hundreds of links, as I have, to determine that Yes, a diet of whole, natural, and unprocessed foods is unarguably the best summation of the foods you eat to provide you with the correct nourishment to lead a healthy life.