| Phases | Median ages | Clinical characteristics |
|---|---|---|
| 0 | Prenatal to birth | Less activity during pregnancy and a smaller birth weight than siblings |
| 1 | At birth | Hypotonia |
| 1a | 0−9 months | Difficulty feeding and decreased appetite |
| 1b | 9−24 months | Enhanced appetite and eating; proper growth |
| 2a | 2.0−4.5 years | Gaining weight in the absence of an increase in appetite or additional calories |
| 2b | 4.5−8.0 years | Heightened interest in and hunger for meals, but feeling full |
| 3 | 8 years-adulthood | Hyperphagic, rarely feels full |
| 4 | Adulthood | Appetite is no longer insatiable |