For a quality nutrition plan avoid eating foods that are rich in fat, saturated fat, monounsaturated fat, or polyunsaturated fat. All fat is fat, the terms they use simply mean "deep fried" or chemically altered. No matter how you look at it, eating too much fat is absolutely horrible for your body.
If you avoid beef because you think it's unhealthy, try grass-fed beef as a healthier alternative. The fats it does have, are the more healthy kind and it's higher in certain vitamins, like E and A. Many people also think it tastes better than grain-fed beef, which is the more common kind.