Changes in lifestyle improve body composition, thyroid function, and structure in obese children

Alterations in thyroid function and structure have been reported in obesity. Function reverses to normal after weight loss, but nothing is known about structure.

To evaluate the effect of weight loss on thyroid function and structure in obese children.

The study was conducted in 72 overweight and obese children. Measurement of free T(3) (fT(3)), free T4 (fT(4)), TSH, antithyroid- antibodies and a thyroid ultrasound was performed at the beginning (phase 1) and after a period of 1.8±1.0 yr of lifestyle intervention (phase 2).

Height SD score (SDS), body mass index SDS, total fat mass did not change from phase 1 to phase 2. Percentage of fat free mass decreased significantly (p<0.05). Waist/height ratio decreased (0.6±0.1 vs 0.5±0.1; p<0.05) as well as waist/hip ratio (0.9±0.1 vs 0.8±0.1; p<0.05). In phase 1, TSH was 2.8±1.7 mU/l; in phase 2, it was 2.2±0.9 mU/l (p<0.05); 17.2% of children showed a TSH level above the normal range (3.6 mU/l) in phase 1, and 6.2% in phase 2 (p<0.05). fT(4) was 10.8±2.2 pg/ml in phase 1 and 10.7±1.9 pg/ml in phase 2. fT(3) was 4.4±1.3 pg/ml (phase 1) and 3.9±1.1 pg/ml (phase 2) (p<0.05). Thyroid volume was -0.5±0.8 SDS (phase 1) and -0.5±1 SDS (phase 2). A non-significant improvement in thyroid structure was observed.

In conclusion, healthier lifestyle improves body composition, thyroid function, and structure.