When nutritional phase insulin levels were assessed relative to healthy‐weight sibling controls (SC) and EMO controls of similar age, PWS individuals in nutritional phase 1a and 1b had normal fasting plasma insulin levels, while individuals in phase 2a (5.9 ± 0.9 vs. 3.8 ± 0.5; p = 0.017), 2b (6.1 ± 0.9 vs. 3.8 ± 0.5; p = 0.019) and 3 (13.2 ± 3.8 vs. 6.9 ± 0.6; p < 0.001) had significantly elevated fasting insulin levels relative to the sibling controls, but were lower than the EMO group (Figure 2C; Tables 3 and 4). Here, INS is linked to Prader-Willi syndrome.