Low-Carbohydrate (Ketogenic) Diet in Children with Obesity: Part 2—Hormonal Effects of the Ketogenic Diet

<b>Background:</b> For decades, the ketogenic diet has been successfully used for the treatment of obesity, metabolic syndrome, and type 2 diabetes. The mechanisms through which it affects metabolism are not fully understood, but the hormonal changes that occur during ketogenic nutrition are likely to play an important role. <b>Objectives:</b> To investigate the effect of the ketogenic diet on various hormones associated with obesity and the accompanying metabolic disorders in childhood. <b>Methods:</b> One hundred children aged 8-18 years with obesity were enrolled. After baseline anthropometric, biochemical, and hormonal testing, they followed a 4-month "well-formulated ketogenic diet." Fifty-eight of them successfully completed the study with follow-up assessments. Among them, 8 girls had polycystic ovary syndrome (PCOS) and 7 children had Hashimoto's autoimmune thyroiditis. <b>Results:</b> At the end of the 4-month period, there was a significant decrease in basal insulinemia (<i>p</i> < 0.0001) and in mean morning cortisol levels (<i>p</i> = 0.04), as well as an increase in adiponectin levels (<i>p</i> = 0.04). All girls with PCOS experienced spontaneous menstrual cycles, accompanied by a reduction in testosterone levels. TSH levels showed no change for the whole group (<i>p</i> = 0.13), but there was a significant decrease in T3 (<i>p</i> < 0.0001) and a mild increase in T4 (<i>p</i> = 0.05). Among patients with Hashimoto's thyroiditis, TSH levels were significantly higher at the end of the study. <b>Conclusions:</b> A short-term, well-formulated ketogenic diet in children with obesity is associated with hormonal changes that support weight loss and improve insulin sensitivity. The diet shows particularly beneficial effects in girls with PCOS and may be considered as part of a comprehensive therapeutic approach in these patients. Monitoring thyroid function during ketogenic nutrition is advisable in patients with hypothyroidism and thyroid disorders.