CFTR and obesity due to melanocortin 4 receptor deficiency: The accelerated growth of overweight and obesity in PwCF observed in recent years (3.5% increase per annum - 2018–2020; 1.1% increase per annum - 2000–2020), has coincided with an increased use of CFTR modulator therapy (CFF, 2019;CFF, 2021;Solomon & Mallory, 2021).