Leptin and its Association with Obesity among Mexican Adolescents

Purpose: To investigate the association between leptin concentrations and nutritional status among a Mexican adolescent population. Methods: Cross-sectional study with 448 adolescents attending five schools in Durango, Mexico. Serum leptin concentrations were measured by ELISA. Other measurements included height, weight, and waist and hip circumference. Body fat of participants was assessed with bio-electrical impedance using a body composition analyzer InBody-720. Sociodemographic information was also collected. Results: Based on IOTF BMI cut-off points, 34.1% of adolescents were overweight and obese and prevalence rates were higher among females (37.1%) than males (29.5%). In agreement with waist circumference, 22.5% of participants were overweight and had abdominal obesity; and based on waist-to-hip ratio 35.5% had truncal obesity. Leptin concentration levels among females (19.33 ng/dL) were two times higher than among males (40.07 ng/dL) with a statistical significant difference (p=0.000). Leptin levels among obese females (69.92 ng/dL) were three times higher than among underweight females (17.70 ng/dL). Conversely, leptin levels among males (43.52 ng/dL) were four times higher than among their underweight counterparts (10.08 ng/dL). Mean leptin levels among women with body fat greater than 28% (46.44 ng/dL) were statistically different and 1.7 times higher than those with lower body fat (25.96 ng/dL) (p=0.000). Mean leptin levels among males with body fat greater than 20% (30.17 ng/dL) were statistically different (p=0.000) and 2.4 times higher than among males with lower body fat (12.35 ng/dL). Among both females and males, leptin concentration levels were positively and significantly associated with visceral body fat (R2=0.344 females; R2=0.373 males; p=0.000). Conclusions: Significant correlations between leptin and BMI, body fat percentage, and visceral adipose tissue area indicate that this hormone can be used as a biomarker for obesity among adolescents

Relationship between Dyslipidemia and Physical Activity in Mexican Children

Purpose: The purpose of this research was to determine the relationship between physical activity and lipid levels in children 10 to 13 years of age living in Durango, Mexico. Method: Cross-sectional study performed in 823 children (n=428, 52% boys; n=395, 48% girls) enrolled in nine elementary schools. Physical activity was monitored in two ways: a) a questionnaire was used to obtain information about physical activity done in the previous week, and b) steps were counted for 24 hours with a Yamax SW-200 pedometer. A subsample of 425 children provided serum samples to determine total-cholesterol (TC), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C) and triglycerides (TG). Results: Over half (52.9%) participated in a sports team inside or outside of school; most (90.9%) reported one sport, with few (9.1%) reporting 2-3 sports. The most commonly reported vigorous PA was: soccer (33%), basketball (24%), jogging (8-12 km/h) (23%), volleyball (17%) and others (3%). Those who participated in a sports team had higher levels of HDL-C and lower TG. Participation in 2 or 3 sports reduced TG levels just over 20%. Boys who reported 30 minutes or more per day of vigorous activity had lower triglyceride levels than those who reported less (p = 0.020). Boys accumulated significantly more steps per day (m=17,030 ± 6444) than girls (m=12,991± 5316; p \u3c 0.001). The prevalence of lipid abnormalities was higher in children with fewer steps. Hypercholesterolemia was lower in boys with the highest number of steps (p = 0.044), in girls the differences were not statistically significant. Hypertriglyceridemia in both sexes was lower in the group with the highest number of steps (

Insulin Resistance and Obesity in Mexican Youth

Purpose: Although research shows that prevalence rates of insulin resistance (IR) is increasing in children, little is known about the impact of obesity in IR in Mexican youth. This study investigated the association between overweight, obesity, and insulin resistance in Mexican adolescents. Methods: Data were collected from 448 adolescents aged 12 to 18 years from a random sample of a high school student population in Durango, Mexico. After fasting overnight, blood samples were obtained from participants. Glucose, insulin, lipid profile, leptin, insulin growth factor, growth hormone, cortisol, TNF-alpha, and C-reactive protein were determined in serum. Body Mass Index (BMI) was calculated using CDC parameters. Fat mass was determined using a bioelectrical impedance analyzer. THE HOMA index was used to calculate IR and a Keskin diagnosis value of 3.1 was considered. Statistical analyses were conducted. Results: The mean age of the sample was 15.44 years and a majority was female (61.4%). Prevalence of overweight and obesity was 31.9%. The BMI mean was slightly higher in females (65.5) than in males (61.1) (p \u3e0.05). Females had a greater mean of body fat percentage (31.9) than males (20.2) (p\u3c 0.05). Prevalence of resistance to insulin by HOMA-IR was 14.4% with no statistically significant gender differences. The IR mean was higher in adolescents with greater BMI (≥85th percentile) than those with low and normal BMI (\u3c85th percentile) (p \u3c0.05). Adolescents with high IR levels (≥3.1) had higher mean values of corporal fat (37.69%) and BMI (89.76) than those with lower IR levels (\u3c3.1) and lower corporal fat and BMI values (26.4%3 and 61.67, respectively). Conclusions: The significant association found between obesity and insulin resistance in Mexican adolescents suggests a greater risk for the development of degenerative disease in this young population during adulthood. Public health programs among Mexican adolescents are essential to prevent obesity and IR related consequences