The On-Therapy Weight Nadir — Appetite Fully Suppressed
Peak drug exposure keeps appetite low and weight at its lowest point.
- −20%: Body weight vs. baseline (typical nadir on therapy)
- ~40%: Appetite drive (well below pre-treatment level)
- 100%: Drug level (steady-state dosing)
- 0%: Weight regained (no discontinuation yet)
GLP-1 receptor agonism suppresses appetite
Drug activates GLP-1 receptors in the hypothalamus and gut, slowing gastric emptying.
Steady dosing holds hunger hormones down
Consistent dosing keeps ghrelin signaling and hunger cues chronically dampened.
Nadir weight reflects sustained caloric deficit, not a permanent metabolic reset.
Discontinuation — Drug Clears and Receptor Signaling Fades
Once dosing stops, plasma drug concentration decays exponentially by half-life.
- ~1 wk: Elimination half-life (typical long-acting agonist)
- ~25%: Drug level at 2 wk (two half-lives elapsed)
- ~5 wk: Full clearance (about five half-lives)
- rising: Appetite drive (starts climbing early)
Exponential decay governs drug clearance
Concentration halves every elimination half-life, following first-order pharmacokinetics.
Receptor occupancy drops before symptoms appear
Appetite suppression lags slightly behind the raw concentration curve.
Clinical effect fades faster than most patients expect after the last dose.
Hunger Hormone Rebound — Ghrelin Rises Toward Baseline
As suppression fades, ghrelin and appetite drive climb back toward pre-treatment levels.
- ~87%: Appetite drive at 8 wk (nearing pre-treatment baseline)
- ↑ rising: Ghrelin trend (ghrelin normalizes over weeks)
- <1%: Drug level (essentially fully cleared)
- minimal: Weight change (regain still just beginning)
Ghrelin and satiety signals re-normalize
Hunger hormone levels drift back up over roughly six to eight weeks.
Appetite can briefly overshoot baseline
Some patients report hunger exceeding pre-treatment levels for a period.
Neuroadaptation lags drug clearance, delaying the felt hunger increase.
Caloric Intake Increases — Measurable Weight Regain Starts
Higher intake outpaces expenditure; body weight trends upward within weeks to months.
- ~50%: Weight regained at 20 wk (of total weight lost, no support)
- weeks: Onset of regain (not months, in most patients)
- ↑ increased: Caloric intake (trending back toward baseline)
- slows regain: Lifestyle support (diet & activity blunt the curve)
Energy balance flips positive again
Rising intake plus unchanged expenditure creates a sustained caloric surplus.
Continued lifestyle support moderates the slope
Diet and activity habits meaningfully slow, but rarely fully stop, regain.
Regain rate is steeper without continued behavioral or drug support.
Outcome — Most Patients Regain a Substantial Fraction of Lost Weight
Within a year off therapy, weight commonly drifts back toward pre-treatment levels.
- ~2/3: Typical regain at 1 yr (of weight lost, no intervention)
- ~1/3: With lifestyle support (regain fraction, meaningfully lower)
- 0%: Drug level (fully cleared for months)
- ~baseline: Appetite drive (near pre-treatment hunger level)
Regain reflects biology, not willpower failure
Hormonal and appetite drive changes largely explain the rebound pattern.
Continued therapy or support changes the trajectory
Ongoing treatment or intensive lifestyle care substantially blunts regain.
Discontinuation without any support predicts the steepest weight rebound.