Stay away from food with high concentrations of saturated fats and high cholesterol. Remember when engaging in a strenuous exercise program you will be burning up fat tissue in the body. Your body will need the right kinds of food to accomplish this goal. Eat as much as your body needs for energy. Don't crash diet just eat the right kinds of food.
Some protein substitutes for red meat are chicken and turkey.
A vegetarian substitute for red meat is beans. White tuna fish in spring water has the highest content of protein.