Could she be pregnant?

Ok my friend had all the signs for being preg. she aint took a home test in like 3 mths but aint had in 4 mths. her belly is startin to grow and she eating alot. sum food makes her sick. could she be 4 mths preg and not no it yet? or was she jus sick and is gaining wieght b/c she eatin alot. she only wieghts bout 100lbs