Finding the sustainable band
A widely cited guideline puts a sustainable rate of fat loss at roughly 0.5 to 1 percent of bodyweight per week. For most people this band is fast enough to stay motivating yet slow enough to protect lean mass and limit the metabolic and hormonal pushback that aggressive dieting provokes. Heavier individuals can often sit toward the upper end safely, while leaner people usually do better toward the lower end.
Expressing the target as a percentage rather than a fixed number of pounds keeps it appropriate as bodyweight changes through the diet.
The cost of going too fast or too slow
Pushing the rate higher tends to increase the share of weight lost from muscle, deepen hunger, and accelerate adaptive slowing, which often backfires into rebound eating. Going much slower is gentler physiologically but can stretch a diet long enough that adherence and patience erode before the goal is reached.
The right pace is the one a person can hold consistently, which is individual. This is general educational information, not medical or dietary advice; consult a qualified professional for a plan suited to your circumstances.