Answering the narrow version, because the broad one does not have a single answer. The dose-response is real but shallow at the top. Across STEP 1 and STEP 4 the gap between 1.7mg and 2.4mg is a couple of percentage points of body weight on average, and the average is carrying a wide spread — plenty of people at 1.7mg sit above the 2.4mg mean. If a dose is working and tolerable, "working" is the relevant variable, not "maximal".

Dr.GastroMayo said:

The dose-response is real but shallow at the top.

That holds for the injectable. The oral formulation has different absorption behaviour and the dose numbers are not interchangeable, which is worth saying out loud because people quote them as if they were.

MaxMetOK said:

Prescribed on cardiovascular grounds rather than for weight, and almost everything written for patients assumes the opposite.

All true, with one condition: that curve is for people who reached the dose on schedule. Anyone who slowed the ladder for tolerability is on a different, flatter curve, and comparing yourself with the published mean will make you feel like a non-responder when you are not.

Adding the clinical framing, because it changes how the question reads.

Mendelian randomization evidence supporting GLP-1 pathway modulation for cardiovascular risk: genetic variants in the GLP1R gene region associated with lower BMI also show associations with reduced cardiovascular risk, confirming a causal pathway[1].

This "natural experiment" (people born with genetically higher GLP-1 signaling being leaner and healthier) provides orthogonal evidence supporting the pharmacological approach. When genetic epidemiology, clinical trials, and mechanistic studies all converge, confidence in the therapeutic approach is high.