Protein is an essential building block of the body. We'd be nowhere without it. It builds lean muscle, and many people don't realize that it also increases the metabolism, which lends a hand in the loss of unhealthy pounds. Protein satisfies our hunger and keeps us satiated for long stretches.
Most Americans predominantly eat red meat. Fish and chicken should not be forgotten though, as they are excellent sources of protein.
For those who are not used to eating much protein, a gradual increase works fine. Add some tuna to your lunch, or some cottage cheese. Enjoy the change.
"The more you begin to replace bad foods with high quality protein, the more effective your weight loss efforts will be. Protein is especially helpful as a mid-day snack, and can provide the fuel you need to get through a tough day and make it until dinner. Low fat cottage cheese is a wonderful source of quality protein, and you can also find good proteins in soy nuts, and other fun snack food."
http://www.weightladder.com/the-role-of-protein-in-weight-loss