The Weight lose diets you can follow to lose weight and have a size smaller is even the cave man diet or Paleo diet of Paleolithic diet created by Loren Cordain, a professor at Colorado State University.
This diet is based on foods that may be hunted, fishing, and took place during the Paleolithic. I mean, meat, fish, shellfish, eggs, nuts, vegetables, roots, fruits and berries.
Today such foods are not readily available because game animals are no longer easily but are domesticated and wild plants but are no longer being cultivated.
So what you do is eat a modified version of the original diet that is gluten free, and includes lean meats, organ meats, fish, poultry, eggs, vegetables, fruits and nuts. It is a wide variety of foods.
The diet does not lead in turn dairy, grains, sugar, pulses, potatoes, oil or any liquid food grown and drinking only water, coconut water or green tea. If you need some sugar found in honey or sugar, coconut, but in very limited quantities.
There is a variation of the diet that promotes fasting, raw foods and nightshade vegetables (like tomatoes or aubergines).
This would be the most extreme and most experts advise against because no one knows what raw foods can contain and harm the body.