What is the maximum sustained weight loss a fat and healthy person safely can have per week?
My rule of thumb is not more that 5% body mass per month which would work out to 1-2% per week. Think of it this way: 1 kg (or 2.2 lbs) of fat is equivalent to 12,000 kCal. Imagine a 12,000 kCal deficit per week for someone modestly overweight at 180 lbs (5’10”) who is losing about 2 lbs per week. Such a person has probably halved his pre-dieting caloric intake from 3000 kCal/day to 1500 kCal/day. Even if he were fasting, the most one would expect is 4 lbs per week for such an individual.
