As part of "Diets that Work", I recommend The Paleo diet.

The Diet has the following principles:

1. Eat: Meat, fish, eggs, vegetables, fruits, nuts, seeds, herbs, spices, healthy fats and oils

Examples:

• Meat
• Fish and seafood
• Eggs
• Vegetables
• Fruits
• Tubers
• Nuts and seeds
• Healthy fats and oils
• Salt and spices

2. Avoid: Processed foods, sugar, soft drinks, grains, most dairy products, legumes, artificial sweeteners, vegetable oils, margarine and trans fats.

Examples:

• Sugar and high-fructose corn syrup
• Grains
• Legumes
• Dairy
• Some vegetable oils
• Trans fats
• Artificial sweeteners
• Highly processed foods

Feedback indicates that this diet is safe and results in huge amounts of weight loss in a short amount of time.

Source: The Paleo Diet — A Beginner's Guide Plus Meal Plan