My sister says her becoming 130 lbs is almost suicidal?

My sister is 5'7 and she is 200 pounds and we are trying to get her to lose weight so I told her to drop down to my weight which is 130 and thats a good size not too skinny not too fat but she says that would be horrible and almost a suicide mission cause it would be unhealthy and too skinny. And so we just fought about that and she just sounds unreasonable am I wrong? Is that weight bad for her?
My sister says her becoming 130 lbs is almost suicidal?
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