Ghrelin levels before and after reduction of overweight due to a low-fat high-carbohydrate diet in obese children and adolescents

BACKGROUND: There are conflicting results for ghrelin changes in reduction of overweight. Increasing ghrelin levels in weight reduction are considered to be responsible for compensatory mechanisms that make the reduction of overweight unlikely to be sustained. METHODS: We have analyzed fasting serum ghrelin levels, weighed dietary record and, as biochemical markers of clinically relevant reduction of overweight, leptin, adiponectin and insulin levels and insulin resistance measured by homeostasis model assessment (HOMA) at baseline and after a 1-y outpatient weight reduction program based on a high-carbohydrate and low-fat diet in 37 obese children (median age 10 y). We divided these children into two subgroups according to their degree of weight loss (substantial reduction of overweight: decrease in SDS-BMI greater than or equal to 0.5). Furthermore, we analyzed ghrelin levels in 16 normal-weight children. RESULTS: Obese children demonstrated significant (P<0.001) lower ghrelin levels compared to normal-weight children. Daily caloric intake (P = 0.004) and percentage fat content decreased significantly (P<0.001), while percentage carbohydrate content increased significantly (P = 0.003) between baseline and 1-y follow-up in the obese children. The substantial reduction of overweight in 16 children (median SDS-BMI=-0.7) was associated with significant changes in insulin resistance (median decrease of HOMA 27%; P=0.013), insulin (median decrease 25%, P = 0.036), adiponectin (median increase 15%; P = 0.003), and leptin levels (median decrease 19%; P = 0.023), while there were no significant changes in ghrelin levels (median increase 4%; P = 0.326). In the 21 children without substantial reduction of overweight (median SDS-BMI = -0.3), there were no significant changes in insulin resistance and in insulin, adiponectin, leptin and ghrelin levels. CONCLUSIONS: We conclude that in obese children, low-fat high-carbohydrate diet-induced weight loss does not change ghrelin secretion, but significantly decreases leptin levels, increases adiponectin levels and improves insulin resistance determined by significantly decreased insulin resistance indices as well as lowered serum insulin levels.