Rather than just stuffing anything into these cute little boxes, if you follow some simple guidelines, it will be guaranteed healthy.
Personally I find it much easier to work out what is going into my box each day when I follow this guidelines.
Firstly get the size of your box correct, then you are halfway there. There are so many cute bento boxes out there it is easy just to pick something that is really cute, but leaves you hungry each day! Definately not a good thing!
Here is the guide I go by for my family:
Young Child (preschool - 7 years old) - a 450ml box
Child or Woman - a 600ml box
Teenager or Man - 900ml box
Of course if you are very active of inactive adjust accordingly. Most shops list the volume of the box in their description or it is printed on the packaging or the bottom of the box.
Now what to pack:
If you think of a Bento Box divided into 6 parts, then 3 parts are carbohydrates (rice, pasta, noodles, bread etc), 1 part is protein (egg, meat, soy, cheese etc), 2 parts is vegetables. You can use fruits as fillers of little gaps to add little sweet treats.
I love the Japanese Healthy Eating Guide called the Spinning Top.
It not only suggests healthy eating, but also water consumption and exercise to keep everything spinning nicely.
It's a great visual for if you aren't eating balanced, then the top will topple over! definately not good :D
If you follow this guide, each 600ml box will hold an average of 400-600 calories, which is great if you are trying to watch your waist line.