Xiao Lei's lunch is: two fried chicken legs and a large bottle of coke. Xiaohong's dinner is: attending a relative's wedding banquet with her parents, chicken, duck and fish,

Chicken, duck and fish are rich in protein and fat, but there are no nutrients such as sugar and vitamins, so I think these two meals are unreasonable. The principles that teenagers should follow in a reasonable diet are: reasonable collocation of main and non-staple foods; Reasonable collocation of coarse and fine grains; Reasonable collocation of meat and vegetables.

Therefore, the answer is: unreasonable; The principles that teenagers should follow in a reasonable diet are: reasonable collocation of main and non-staple foods; Reasonable collocation of coarse and fine grains; Reasonable collocation of meat and vegetables.