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Body Fat Percent by Bioelectrical Impedance Analysis and Risk of ...

Body Fat Percent by Bioelectrical Impedance Analysis and Risk of ...

a 1991 census. We

a 1991 census. We excluded 16 suburban streets and randomly selected 20 out of the remaining 180 streets considered urban. We randomly selected 20 to 50 adult men by blindly selecting a card out of 50 to 150 cards from each street as described earlier [12]. Each street contained 6 to 12 blocks, and any block containing 100 to 300 subjects was designated a cluster. All subjects were informed and a verbal consent taken by means of pamphlets distributed to inform subjects of the survey’s utility in the prevention of diseases. They were also given their individual results along with free advice and referred for evaluation and treatment if needed. We contacted 999 adult men aged 25 to 64 years out of which 95 (9.5%) were unable to give time for detailed histories and blood tests. The remaining 904 men were invited for this study; however, bioelectrical impedance analysis was done in 850 randomly selected subjects. A pretested and validated questionnaire [8], prepared according to guidelines of the World Health Organization [13] and other Indian studies [14], was used by the dietitian and a physician for collection of data from all the subjects. The questionnaire included information on age, socioeconomic status, physical activity, ethnicity, occupation, past history of diabetes, hypertension, chest pain (Rose questionnaire) and smoking. All subjects were graded in social classes one through five based on attributes of education, occupation, housing, consumer durables and per capita income [16]. Body composition was determined by a body-fat analyzer (BF 905, Maltron, UK) [10,11] in 850 subjects. The body-fat analyzer measures the flow of electrical signals as they pass through fat and lean areas and water in the body. When the amount of fat and lean matter or water changes, so do the signals, giving a reliable and accurate measure of the amount of each of these components that make up the total weight of the person. Body-fat-percent categories for our analysis were as follows: �10, under-body-fat, 10 to 20 normal-fat, 20 to 25 over-fat and �25 higher-body-fat. These categories corresponded approximately to percentiles 0 to 25, 26 to 54, 55 to 64 and �65 of the body-mass index. These values were also in accordance with height-weight tables of average values for Indian men advised by the Life Insurance Corporation of India. Physical activity was assessed by ascertaining occupational and spare-time physical activities, and subjects were then graded into sedentary, mild, moderate and heavy based on scores of activities as described earlier [12]. Height, weight and blood pressure were recorded in all the subjects [13]. Body weights were measured by the dietitian independently in light underclothes to the nearest of 0.5 kg. Height was measured in standing position. Waist and hip girths were measured in a standing position. Waist was measured as the smallest horizontal girth between the costal margin and the iliac crests and hip as the greatest circumference at the level of the greater trochanters. Blood pressure (systolic and diastolic phase V of Korotkoff) was measured in the right arm after five minutes rest with the cuff fitted while the subject was sitting. A standard mercury sphygmomanometer was used by the same physician for bloodpressure measurement in all the subjects. A final reading in lying position was recorded in all those subjects having high blood pressure �140/90 mmHg in the lying position after five minutes rest in accordance with World Health Organization Guidelines [13]. In all subjects a 12-lead electro-cardiogram was recorded for the diagnosis of CAD. Diagnostic Criteria The diagnosis of high blood pressure was made when the systolic blood pressure was 140 mmHg or more and the diastolic 90 mmHg or more in accordance with the guidelines of the WHO/ISH hypertension liaison committee [15]. Diabetes mellitus was diagnosed if the fasting blood glucose was more than 7.7 mmol/L (�140 mg/dL) and postprandial blood glucose more than 11.1 mmol/L (�200 mg/dL) two hours after intake of 75 grams of glucose orally. Serum cholesterol was considered higher if it was more than 5.18 mmol/L (�200 mg/dL) and triglycerides higher if they were more than 2.08 mmol/L (�185 mg/dL). Low high-density lipoprotein cholesterol was considered when it was less than 0.9 mmol/L (�35 mg/dL) [14]. Body-mass index was calculated and obesity defined [1,14] as a body mass index of �25 kg/m 2 and overweight as a body mass index of �25 kg/m 2 . Sedentary lifestyle was considered in cases of office workers or shopkeepers if they walked fewer than two kilometers a day and climbed fewer than 20 flights of stairs a week without any vigorous activity at least five days of the week based on Indian criteria of activities [16]. In India, tobacco is consumed by more than one means among them cigarettes, beedies, Indian pipes, raw tobacco and chewing tobacco. Users of any form of tobacco were categorized as smokers as has been done in other studies [17]. Alcohol intake is not common in India. The criteria [13] for the diagnosis of CAD were (a) history of angina or infarction and previously diagnosed disease, (b) affirmative response to a Rose questionnaire and (c) electrocardiographic findings, namely the Minnesota codes 1-1, 4-1, 5-9, 5-2 or 9-2. Presence of any of these criteria was taken as confirmation of the diagnosis of CAD. Individual clinical criteria such as known CAD, affirmative response to a Rose questionnaire and electrocardiographic changes (Q wave changes codes 1-1 and 1-2), ST segment depression or elevation codes 4-1, 4-2 and 9-2 and T wave inversions, codes 5-1 and 5-2, were also recorded. Laboratory Data Body Fatness and Coronary Disease in India Blood samples were collected in the lying position using a tourniquet after a overnight fast. Total cholesterol and triglycerides were estimated by enzymatic methods. High density lipoprotein cholesterol was estimated after precipitation of nonhigh-density lipoprotein cholesterol with managese heparin substrate. Low-density lipoprotein cholesterol was obtained JOURNAL OF THE AMERICAN COLLEGE OF NUTRITION 269

Body Fatness and Coronary Disease in India using Friedewald’s formula: low density lipoprotein�total cholesterol � high density lipoprotein � (triglycerides/5). All blood samples were analysed on the day of blood collection. Statistical Analysis All p values were two tailed, and significance was taken as p�0.05. A relation was determined between body-fat percent and prevalence of CAD and hypertension, hypercholesterolemia, diabetes mellitus, smoking and sedentary lifestyle, and the significance of any trend was calculated with the Mentel- Haenzel X 2 test. Body-mass index, systolic and diastolic blood pressure, total cholesterol, HDL cholesterol and triglycerides were determined at various levels of body fat percent, and the significance of trends was checked by Kendall’s test. Spearman’s coefficient of rank correlation (r) was calculated for status of body-fat percent with various clinical and biochemical risk factors. We used the SPSS statistical package (SPSS Inc, Chicago) for analysis of our data. RESULTS The body-fat percent categories of the various age groups of the 850 men are shown in Table 1. There was positive correlation of age with body-fat percent (Spearman’s r�men 0.45, p�0.01). We found an overall increase in the prevalence of clinical and electrocardiographic CAD among obese and overweight subjects based on body-fat-percent criteria, and the trend was significant as shown in Table 2. Social classes 1 to 3 (higher and middle socioeconomic status) were more common among over- and high-fat subjects than normal- and low-fat subjects respectively (91.1% vs. 45.6%, p�0.01). Higher social classes 1 to 3 were mainly from families of professionals, business persons, shopkeepers and skilled workers and social classes four and five had physically demanding occupations. About half of the men were Hindus and half were Moslems and access to health care was adequate. The prevalence of coronary risk factors among people of various body-fat percent is shown in Table 3. An increasing level of body-fat percent was associated with a significant rising trend in the prevalence of hypercholesterolemia, hypertension, diabetes mellitus and sedentary lifestyle. However, smoking was greater among normal- and under-fat subjects. Table 1. Distribution [n (%)] of Body Fat Percent Categories among Men of Different Age Groups Age groups No. of Under body Normal fat Subjects fat (�10%) (10–20%) Over fat (21–25%) High fat (�25%) 25 to 34 284 26 (9.1) 88 (30.9) 70 (24.6) 100 (35.2) 35 to 44 275 27 (9.8) 62 (22.5) 70 (25.4) 116 (42.2) 45 to 54 170 5 (2.9) 26 (15.2) 55 (32.3) 84 (49.4) 55 to 64 121 5 (4.1) 24 (19.8) 35 (28.9) 57 (47.1) TOTAL 850 63 (7.4) 200 (23.5) 230 (27.0) 357 (42.0) Body-mass index, total and high-density lipoprotein cholesterol, triglycerides and systolic blood pressure also showed an increasing trend with increase in body-fat percent. Diastolic blood pressure showed no significant association with body fat percent (Table 4). There was a significant positive rank correlation of the level of body-fat percent with age, body-fat weight, body weight, body mass index, waist-hip ratio and systolic blood pressure (Table 5). No significant rank correlation of body fat percent was observed with diastolic blood pressure, total cholesterol and low-density lipoprotein cholesterol. However, high-density lipoprotein cholesterol showed significant negative and triglycerides positive rank correlation with body fat percent. DISCUSSION This study shows that CAD and coronary risk factors were significantly associated with the level of body-fat percent determined by bioelectrical impedance analysis in a cohort of urban men in north India. High fat and overfat subjects were associated with a high prevalence of CAD. Hypercholesterolemia, hypertension, diabetes mellitus and sedentary lifestyle were also more prevalent among high-fat and over-fat people. On the other hand smoking was more common among underfat people. There is scant evidence on the association of bodyfat percent with coronary risk factors [11,18]. Studies in developed countries [19–21] showed that insulin resistance and high-plasma triglycerides levels were important correlates of truncal obesity, which is an important risk factor for CAD in south Asians. These investigators proposed a link between regional fat accumulation, regional variation in adipocyte morphology and lipolytic activity and the metabolic profile. Since then, results from several epidemiological studies [3–8,21] have shown that a high proportion of fat on the trunk or abdomen was associated with an increased probability of developing cardiovascular disease in association with insulin resistance [22]. South Asians have a tendency toward abdominal obesity and insulin resistance [4–9]; however, no study has examined the association of body-fat percent with CAD. In one study [18] among 453 Thai females, the prevalence of overall obesity (27.0%) and central obesity (54.1%) (WHR �0.80%) was quite high. Total and low density lipoprotein cholesterol, triglycerides, apo B and fasting blood glucose showed significant increases with increase in body-mass index or body fat measured by bioelectric impedance. In another study [11] among 205 American female adults, intake of dietary fat was significantly related to adipocity and body-fat percent with control for multiple potential confounding factors. Changes in body-fat percent may be dependent on an imbalance between energy intake and energy expenditure. As Indians become affluent, urbanized and mechanized, the demand for physical activity declines and the energy is stored as 270 VOL. 18, NO. 3

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