Short- and long-term relationships of serum ghrelin with changes in body composition and the metabolic syndrome in prepubescent obese children following two different weight loss programmes

Abstract

Objectives: Ghrelin has been proposed to be a regulator of energy balance, and its dysregulation may be important in obesity. The aims of this study were (i) to compare short- and long-term changes in circulating ghrelin concentration after increasing energy expenditure vs. its changes after decreasing energy intake, (ii) to determine factors associated with changes in ghrelin level, and (iii) to assess relationships of ghrelin concentration with metabolic syndrome (MetS) in prepubescent obese children.

Design: Randomized controlled trial.

Patients: About 100 obese children aged 7-9 years.

Measurements: After baseline testing, children were randomly assigned to two interventional groups, either receiving dietary recommendations or engaging in physical training classes for 6 months. Ghrelin, insulin, leptin, fasting blood sugar, lipid profile and anthropometric indexes, as well as energy intake and expenditure were measured.

Results: Of the participants, 92 completed the 6-month trial, and 87 returned for the 1-year follow-up. Except ghrelin level, other biochemical variables had no significant change at 12- vs. 6-month follow-up. In both groups, ghrelin showed a progressive increase in the periods of time with significant reduction of overweight and negative energy balance; while after the end of the trial, when children regained weight, it decreased toward baseline levels. Baseline ghrelin had strong negative correlation with measures of central obesity. The odds of having the MetS were 12% lower in the middle and 37% lower in the highest tertile of ghrelin level. As the number of MetS components increased, there was a progressive decrease in ghrelin and quantitative insulin sensitivity check index (QUICKI), with a progressive increase in serum insulin, HOMA-R and leptin levels.

Conclusions: Ghrelin increases in response to overweight reduction and negative energy balance resulting from either an exercise intervention or reduction in food intake in prepubescent obese children. It is unlikely to regulate long-term energy balance in young obese children.