Fat cell size, insulin sensitivity, and inflammation in obese children.

OBJECTIVE: To assess the association between adiposity indexes (body mass index [BMI], fat mass, adipocyte size) and circulating inflammation markers with known metabolic relevance or insulin sensitivity in overweight/obese children. STUDY DESIGN: Twenty-eight children (males/females: 13/15) with different degrees of overweight (BMI z-score: 1.64-3.1; fat mass: 14.1-49.8 kg) were studied. BMI, body composition (dual-energy x-ray absorptiometry scanning), subcutaneous adipocyte diameter (needle biopsy of subcutaneous abdominal fat), blood tumor necrosis factor-alpha and interleukin-6 concentrations and insulin sensitivity (frequently sampled intravenous glucose tolerance test) were assessed. RESULTS: Adipocyte diameter, more than BMI and fat mass, was significantly associated with interleukin-6 (r = 0.62, P < .001) and tumor necrosis factor-alpha (r = 0.61, P < .001). Moreover adipocyte size was associated with insulin sensitivity (R2 = 0.15, F = 4.69, P = .04) independently from fat mass. CONCLUSIONS: Adipocyte size is a factor linked to both inflammation and insulin resistance in overweight/obese children. This is similar to the findings in adults and lends support to the tenet that the earlier obesity ensues, the more severe the biologic consequences may be.

Prevalence of overweight and obesity in 2- to 6-year-old Italian children.

OBJECTIVE: To assess the prevalence of overweight and obesity in 2- to 6-year-old Italian children and to compare the prevalence between the north and the south of the country. RESEARCH METHODS AND PROCEDURES: This was a cross-sectional study of 2150 subjects (M/F: 1137/1013), 5.36 +/- 0.83 years of age. The sampling areas were Verona (north Italy) and Messina (south Italy). We used definitions of overweight and obesity using BMI values, with cut-off values proposed by the International Obesity Task Force. RESULTS: The prevalence of overweight was 16.6% (males: 13.9%, females: 19.6%), and it was higher in the south (males: 17.8%, females: 22.4%) than in the north (males: 11.3%, females: 17.9%). The prevalence of obesity was 8.0% (males: 8.3%, females: 7.7%), and it was higher in the south (males: 12.3%, females: 10.7%) than in the north (males: 5.7%, females: 5.8%). Using the Centers for Disease Control reference charts, the prevalence of overweight and obesity of Italian children was close to that reported in children living in the United States (32% vs. 32.7%, respectively). DISCUSSION: The prevalence of overweight and obesity in young Italian children is very high, and it is rapidly growing. In the south of the country, the prevalence is higher than in the north.

Effects of dinner composition on postprandial macronutrient oxidation in prepubertal girls.

OBJECTIVE: To see whether a fat-rich (50%) evening meal promoted fat oxidation and a different spontaneous food intake on the following day at breakfast than a meal with a lower fat content (20%) in 10 prepubertal obese girls. RESEARCH METHODS AND PROCEDURES: The postabsorptive and postprandial (10.5 hours) energy expenditure after a low-fat (LF) (20% fat, 68% carbohydrate, 12% protein) and an isocaloric (2.1 MJ) and isoproteic high-fat (HF; 50% fat, 38% carbohydrate, 12% protein) meal were measured by indirect calorimetry. RESULTS: Fat oxidation was not significantly different after the two meals [LF, 31 +/- 9 vs. HF, 35 +/- 9 g/10.5 hours, p = not significant (NS)]. The girls oxidized 1.8 +/- 0.9 times more fat than that ingested (11.1 grams) with the LF meal vs. 0.3 +/- 0.3 times more fat than that ingested (27.1 grams) with the HF meal (p < 0.001). Carbohydrate oxidation was significantly higher after an LF than an HF meal (39 +/- 12 vs. 29 +/- 9 g/10.5 hours, p < 0,05). At breakfast, the girls spontaneously ingested a similar amount of energy (1.5 +/- 0.7 vs. 1.5 +/- 0.6 MJ, p = NS) and macronutrient proportions (fat, 23% vs. 26%, p = NS; protein, 9% vs. 10%; carbohydrate, 68% vs. 64%,) independently of their having eaten an HF or an LF dinner. DISCUSSION: An HF dinner did not stimulate fat oxidation, and no compensatory effect in spontaneous food intake was observed during breakfast the following morning. Cumulated total fat oxidation after dinner was higher than total fat ingested at dinner, but a much larger negative fat balance was observed after the LF meal. Spontaneous energy and nutrient intakes at breakfast were similar after LF and HF isocaloric, isoproteic dinners. This study points out the lack of sensitivity of short-term fat balance to subsequently readjust fat intake and emphasizes the importance of an LF meal to avoid transient positive fat imbalance.

Insulin resistance and the persistence of obesity from childhood into adulthood.

Insulin resistance and obesity are associated in children as they are in adults. However, although insulin resistance seems to oppose further weight gain in adults, opposite results have been found in children. To investigate the relationship between childhood obesity, insulin resistance, and long-term weight gain, we selected 215 obese Caucasian children (120 males and 95 females) aged 10.5 (+/-2.4) yr, with a relative body mass index (BMI) of 153.8% (+/-27.7%) and normal glucose tolerance. Insulin resistance was assessed at baseline by using the homeostasis model assessment. Fourteen (+/-5) years later, 103 subjects returned for a follow-up examination of height and weight. At follow-up, 37 subjects (36%) were obese (BMI > or = 30), 33 (32%) were overweight (25 < or = BMI < 30), and 33 (32%) were of normal weight (20 < or = BMI < 25). In a multiple regression, relative BMI and insulin resistance at childhood were independent predictors of adulthood BMI (r(2) = 0.44; P < 0.01) in girls. A multivariate logistic regression analysis showed that high relative BMI [odds ratio, 1.06; 95% confidence interval, 1.00-1.13; P = 0.04] and low insulin resistance index at baseline (odds ratio, 0.58; 95% confidence interval, 0.34-0.99; P = 0.04) predicted obesity in adulthood for girls, no matter their age, Tanner stage, and their parents' BMI. In boys, insulin resistance was not a significant predictor of adult obesity. In conclusion, obesity tracks into adulthood for many obese Caucasian children. In obese girls, insulin resistance during childhood appears to oppose the risk of obesity in adulthood.