Malnutrition is not just not having enough food to eat, you could eat properly but still be undernourished, why?
You see protein is the food that makes our bodies look the way they are, and they body building process takes place at night when you are in deep sleep, take note Deep Sleep and that is in a course of about 6hrs while sleeping. So if you are the type that always forces his/her self to sleep i.e. it doesn't come naturally and your sleep is not the lenghty type, then you should expect problems like, balding, greying hairs, eye problems, organ failures, yeah you guessed it weight gain because anything the body doesn't use it stores since the body is not being rebuilt. Our cells die everyday so ensure your rebuilding process is not cut short for too long.
Thanks, keep living Life.