Nutritional and Health-Related Environmental Studies (NAHRES)

Body fat and its relationship with metabolic syndrome indicators in overweight pre-adolescents and adolescents

Background

WHO has declared overweight and obesity a crisis of "epidemic proportion" in the world, with 300 million of people globally estimated to be obese. Obesity is listed in the WHO world health report among the top ten preventable risks leading to morbidity and mortality (WHO, 2002). In the USA, the prevalence of overweight and obesity among children and adolescents aged 6-18 years increased from 15% in the 1970s to more than 25% in the 1990s. Such increases are not restricted to developed countries; in Brazil, the prevalence of overweight and obesity among children and adolescents 6-18 years old has tripled from 4% in the mid 1970s to over 13% in 1997 (WHO, 2004).

Childhood obesity is a major risk factor for obesity in adulthood, which in turn is a significant risk factor for increased morbidity and mortality. Childhood obesity has been linked to hyperlipidemia, diabetes, hypertension, and atherosclerosis. Due to long-term adverse effects of childhood obesity, its prevention and management have been recognized as a public health priority in many countries particularly those in nutrition transition. In this context, WHO is working with its Member States to implement the Global Strategy on Diet, Physical Activity and Health, which was adopted at the May 2004 World Health Assembly (WHO, 2004).

Overweight and obesity are defined as an excess of body fat. Children and adolescents can be defined as overweight or obese based on reference percentiles of BMI (body weight/hight2) for age. However, although BMI for age standards is a widely accepted approach for classifying overweight and obesity, careful interpretation of weight-height relationships is required in children and adolescents with low stature resulting from chronic undernutrition.

Moreover, the assumption that BMI can classify overweight and obesity in all ethnic groups of children and adolescents has not been demonstrated. Adults of different ethic groups have significantly different BMI at the same amount of body fat, age and gender. Possible reasons for ethnic differences in the relationship between BMI and body fat include differences in fat free mass, body density and the distribution of subcutaneous fat. This suggests that ethnicity should be considered when interpreting data on BMI and its relationship with body fat body and health risks.

In adults, the relationship between excess body fat and increased risk of non- communicable diseases has been documented. Intra-abdominal adipose tissue is the most clinically relevant type of body fat. Metabolic complications and adverse health effects of increased abdominal fat include high blood pressure, hyperinsulinemia, type II diabetes and dyslipedimia. However, in children, pre-adolescents and adolescents, the relationship between body fat and risk factors is not clear.

Objective
Overall objective
  • To establish the relationship between body mass index (body weight/stature2) and body fat and explore the association with indicators of the metabolic syndrome in pre-adolescents and adolescents in different ethnic group
Specific objectives
  • To define the relationship between BMI and body fat in pre- adolescents of 9 years at first Tanner stage of puberty (T-1) and adolescents of 16 years at 4th and 5th Tanner stages of puberty (T4-5) who are at risk of overweight (above the 85th percentile of BMI for age according to the CDC charts) in different ethnic groups.
  • To determine the association between body fat and insulin, glucose, blood pressure in pre-adolescents of 9 years at first stage of puberty (T-1) and adolescents of 16 years at 4th and 5th Tanner stage who are at risk of overweight (above the 85th percentile of BMI for age according to the CDC charts) in different ethnic groups.
Expected research outputs

Data from different ethnic groups of pre-adolescents and adolescents on:

  • Relationship between BMI and body fat
  • Impact of body fat on components of the metabolic syndrome
Proposal submission forms

Research institutions in Member States interested in participating in this CRP are invited to submit proposals, using the standard forms, directly to the Research Contracts Administration Section (NACA) of the International Atomic Energy Agency: Official.Mail@iaea.org or to Ms. Najat MOKHTAR: n.mokhtar@iaea.org.

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Deadline for submission of proposals

Proposals must be received by the contract administration section or Najat Mokhtar no later than October 28, 2005. Transmission via E-mail is acceptable if all required signatures are scanned.