الفهرس 
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Abstract
Obesity can be defined as a condition of abnormal or excessive fat accumulation in the adipose tissue to the extent that health may be impaired. The WHO classified obesity according to the BMI, which is the weight of the patient in kilograms (kg) divided by his squared height in meters (m2). The normal BMI should remain between 18.5 to < 25 kg/m2, so that subject is considered overweight when BMI is between 25 - < 30 Kg/m2, and obese when his BMI is more than 30 Kg/m’1. Unfortunately BMI have very important limitations, as it does not distinguish between FM and FFM, so people with large amounts of LTM, may have a high BMI while having their BF% in a healthy range. In addition, a healthy BMI does not necessarily mean that BF% is within the healthy range. Also BMI does not give any information on the location of the body fat, which is important in determining obesity-related risk for disease. It is important to have a measure that is relatively easy to use, and that can be applied in clinical and research settings. However, the use of measures such as the WC, WHR and Sum SFT assumes that these measures represent the distribution of fat independent of ethic group. Recent studies have shown .systematic differences in the relation of these measures to fat distribution in children, adolescence and elderly population. For this reason the BF: BMI, a novel ratio for assessing obesity, is introduced in the present study for the Egyptian population. Derivation of this ratio is based on the observation that different ethnic groups have widely different BF% for a similar level of BMI.
Body weight is determined by an interaction between genetic, environmental and psychosocial factors acting through the physiological mediators of energy intake and expenditure. Hence, the adverse effects of obesity, represented in the dyslipidemia, elevated FBG and NO levels are mainly related to the FM and not BMI, it was important to compare the different correlations between these adverse effects of obesity and BMI, FM, truncal FM, fat content in food and daily caloric intake, in a trial to identify fast screening method for obesity for research and clinical use.1 We also investigated if education, socioeconomic class, family history of obesity, number of pregnancies and children, early menarche or eating episode were correlated to FM, in a trial to identify population at particular risk of obesity and its associated health problems, hoping for prevention than treatment.
Nowadays, for most clinicians, the gold standard for determining FM is DXA, that’s why it was chosen to be our reference method for FM estimation. Unfortunately, an important and unresolved concern is whether and to what extent variation in ST hydration causes errors in DXA FM and FFM estimates. from our biophysical point of view, this could be avoided by applying DXA physical hydration models and then simulating errors arising from hypothetical Overhydration states. Based on this, we tried to investigate if we can rely on the DXA as an accurate estimation for this amount of fat in the body, even with different ranges of hydration and fat content. According to-this we investigated the accuracy of DXA with different simple elemental body contents, then with mixtures of these compounds. When the model got validated, two models were investigated, one with increasing levels of hydration and the other with increasing amounts of fat with fixed level of hydration. Results clearly showed that DXA fat estimation errors occur as a function of added fluid R-value, fraction of added fluid and soft tissue composition, but the magnitude of these errors is small when considered in the context of the physiological range of accumulated fluid compatible with life. Hydration, including fluid and electrolyte balance, is maintained remarkably stable in healthy subjects. Simulated experiments
Obesity can be defined as a condition of abnormal or excessive fat accumulation in the adipose tissue to the extent that health may be impaired. The WHO classified obesity according to the BMI, which is the weight of the patient in kilograms (kg) divided by his squared height in meters (m2). The normal BMI should remain between 18.5 to < 25 kg/m2, so that subject is considered overweight when BMI is between 25 - < 30 Kg/m2, and obese when his BMI is more than 30 Kg/m’1. Unfortunately BMI have very important limitations, as it does not distinguish between FM and FFM, so people with large amounts of LTM, may have a high BMI while having their BF% in a healthy range. In addition, a healthy BMI does not necessarily mean that BF% is within the healthy range. Also BMI does not give any information on the location of the body fat, which is important in determining obesity-related risk for disease. It is important to have a measure that is relatively easy to use, and that can be applied in clinical and research settings. However, the use of measures such as the WC, WHR and Sum SFT assumes that these measures represent the distribution of fat independent of ethic group. Recent studies have shown .systematic differences in the relation of these measures to fat distribution in children, adolescence and elderly population. For this reason the BF: BMI, a novel ratio for assessing obesity, is introduced in the present study for the Egyptian population. Derivation of this ratio is based on the observation that different ethnic groups have widely different BF% for a similar level of BMI.
Body weight is determined by an interaction between genetic, environmental and psychosocial factors acting through the physiological mediators of energy intake and expenditure. Hence, the adverse effects of obesity, represented in the dyslipidemia, elevated FBG and NO levels are mainly related to the FM and not BMI, it was important to compare the different correlations between these adverse effects of obesity and BMI, FM, truncal FM, fat content in food and daily caloric intake, in a trial to identify fast screening method for obesity for research and clinical use.1 We also investigated if education, socioeconomic class, family history of obesity, number of pregnancies and children, early menarche or eating episode were correlated to FM, in a trial to identify population at particular risk of obesity and its associated health problems, hoping for prevention than treatment.
Nowadays, for most clinicians, the gold standard for determining FM is DXA, that’s why it was chosen to be our reference method for FM estimation. Unfortunately, an important and unresolved concern is whether and to what extent variation in ST hydration causes errors in DXA FM and FFM estimates. from our biophysical point of view, this could be avoided by applying DXA physical hydration models and then simulating errors arising from hypothetical Overhydration states. Based on this, we tried to investigate if we can rely on the DXA as an accurate estimation for this amount of fat in the body, even with different ranges of hydration and fat content. According to-this we investigated the accuracy of DXA with different simple elemental body contents, then with mixtures of these compounds. When the model got validated, two models were investigated, one with increasing levels of hydration and the other with increasing amounts of fat with fixed level of hydration. Results clearly showed that DXA fat estimation errors occur as a function of added fluid R-value, fraction of added fluid and soft tissue composition, but the magnitude of these errors is small when considered in the context of the physiological range of accumulated fluid compatible with life. Hydration, including fluid and electrolyte balance, is maintained remarkably stable in healthy subjects. Simulated experiments