The Netherlands Twin Register Biobank project identified 17 monozygotic twin pairs with a BMI discordance of ≥3 kg/m2 (follow-up 6 years) and found worse obesity-related blood biomarker profiles (glucose, insulin, total cholesterol, LDL, HDL, triglycerides, CRP, IL-6, sIL-6R, GGT) in heavier (compared to leaner) twins [25]. Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.