"A loss of 5% or more of body weight in one month is usually considered unhealthy (for example, a 150 pound person should not lose more than 71/2 pounds in one month)."
Why is this important?: "Too much weight loss can make a person weak, change how medicine works in the body, or cause the skin to break down which can lead to pressure sores. Too much weight loss may mean that the resident is ill, refuses to eat, is depressed, or has a medical problem that makes eating difficult (like weakness caused by a stroke). It could also mean that the resident is not being fed properly, their medical care is not being properly managed, or that the nursing home's nutrition program is poor. To help prevent unhealthy weight loss, it is important that the resident's diet is balanced and nutritious, and that staff spend enough time feeding people who can't feed themselves. Sometimes it may be necessary for a person to lose weight for medical reasons. In these cases, the medical staff may plan in advance for the resident to lose weight on a special weight loss program, but the person should not lose more than 5% of body weight in one month."
Taken from the Center for Medicaid and Medicare Services: Nursing Home Information for Consumers