Height and weight proportional (HWP) is a descriptive term that is typically displayed as an acronym in online dating and is used to indicate that a person’s weight is within the average range for their height. The descriptor is most commonly seen in personal ads or online dating profiles.
Although this term can mean a number of things, it does suggest that a person is looking for a partner whose weight might be considered "average" or "healthy," and is typically considered a euphemism for "not overweight."
Clearly, HWP is a subjective term and, while it does not specify exactly what size or weight of person would be considered unacceptable, it does point to a certain level of size discrimination.