Why won't Gretl give me a weight-loss target?

Because your height and weight put you at or below a BMI of 18.5, or because a goal weight you've set would. At that point the app calculates maintenance instead — what your body appears to need — and says so rather than quietly showing you a smaller number. No pace setting, custom target or goal changes it.

This isn't a judgment about you, and it isn't permanent. It's a line an app doesn't have the standing to cross: whether losing weight from here is a good idea is a question for a doctor or a registered dietitian, who can actually examine you. If you'd like to talk it through with someone, the helpline above is a good place to start.