A slow responder is someone who sees little effect from a GLP-1 medication at standard starting or mid-range doses, and needs a longer titration period or a higher maintenance dose before noticing meaningful appetite suppression or weight loss. That is often normal variation in individual response. Patience through the titration schedule, and a conversation with your prescriber about dose adjustments, is the typical path forward.
Some people, though, lose little weight even at the full dose, and labels build in a check for this. Saxenda's, for example, tells adults to stop if they haven't lost 4% of their weight by 16 weeks (Saxenda prescribing information (external link)). If your weight loss stays minimal at the full dose, ask your prescriber whether this medication is the right one for you.