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Original Paper |
Centre of Nutrition, Medical Hospital and Research Centre, Moradabad, INDIA
Address reprint requests to: Dr. R. B. Singh, Hon. Prof. Preventive Cardiol, MHRC, Civil Lines, Moradabad-10 (UP) 244001, INDIA
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONSUBJECTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Subjects and Methods: We randomly selected 850 men, aged 25 to 64 years. The survey methods were questionnaire and bioelectrical impedance analysis for body composition. Subjects were divided into high-fat (n=357), over-fat (n=230), normal-fat (n=200) and under-fat (n=63) based on criteria of body-fat percent analysis.
Results: The prevalence of CAD and the coronary-risk factors hypercholesterolemia, hypertension, diabetes, mellitus and sedentary lifestyle were significantly associated with high and moderate body fat percent despite low body-mass index (23.6±4.1 kg/m2). Mean total cholesterol, triglycerides and blood pressure were significantly associated with high and moderate body fat percent. The prevalence of smoking was weakly but inversely associated with high body-fat percent. Mean HDL cholesterol was positively associated with high body-fat percent. Body mass index was positively associated with high body-fat percent.
Conclusions: High and moderate body-fat-percent subjects were associated with high prevalence of CAD and the coronary-risk factors hypertension, diabetes mellitus, higher body-mass index and sedentary lifestyle.
Key words: body fat, bioelectric impedance, cholesterol, triglycerides, obesity
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONSUBJECTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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SUBJECTS AND METHODS |
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TOPABSTRACTINTRODUCTIONSUBJECTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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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 blood-pressure 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/m2 and overweight as a body mass index of >25 kg/m2.
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
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 non-high-density lipoprotein cholesterol with managese heparin substrate. Low-density lipoprotein cholesterol was obtained 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 X2 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.
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RESULTS |
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONSUBJECTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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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 excess body fat [1,2]. There is increasing evidence that dietary fat is particularly more conducive to weight gain than complex carbohydrates. We have reported that Indian rural subjects consuming low-fat diets and having physically demanding occupations have significantly lower body-mass indices and lower rates of obesity than urban subjects consuming relatively higher fat diets [7–9]. It is possible that hepatic handling of insulin is modulated by habitual fat intake, and, on a high-fat diet, insulin secretion may rise to suppress hepatic glucose production resulting in insulin resistance characterized by greater body fat percent, particularly in the abdomen [7–9]. Higher fat diet appears to be a risk factor of higher body fat percent [11]. We found a positive correlation of age with body-fat percent (Table 1). The criteria for normal body fat may change with age. A high body-fat content for a 20-year-old man may be considered normal for someone who is 50 years old.
We also found a higher prevalence of hypertension, hypercholesterolemia, diabetes mellitus and sedentary lifestyle in association with greater body-fat percent. It is possible that higher body-fat percent predisposes these risk factors, mainly by causing insulin resistance and central obesity. However abdominal obesity based on waist-hip ratio among Thai women did not influence blood lipids which were related to body-fat percent [18]. It seems that excess body-fat percent in conjunction with a sedentary lifestyle, directly predisposes individuals to these risk factors. It is possible that excess of body-fat percent acts conjointly with other variables in increasing the prevalence of CAD. Presence of coronary risk factors among high-fat and over-fat subjects may increase the prevalence of CAD and the excess burden of ill health noted in other studies [23].
Magnetic resonance imaging, computarised axial tomography and body density derived from underwater weighing are other more accurate methods for measuring the body fat percent. However these methods are difficult and expensive for a population study when compared to bioelectrical impedance analysis [2,18]. We also observed that smoking was more common among under-fat subjects. Smoking is known to cause loss of appetite and decrease energy intake [24]. It is not clear why under-fat subjects, despite greater smoking, had a lower prevalence of CAD. It is possible that greater physical activity due to physically demanding occupations and low-fat diet may have protected these subjects against risk of CAD. We can not exclude possible bias; selection, nonresponse and measurement error, confounding by variables not measured, chance variation in a small sample and lack of generalizability to other populations or to women are the major limitations of this study.
In conclusion, the findings of our study indicate that body-fat percent was positively associated with CAD and the coronary risk factors hypertension, body mass index, diabetes mellitus and sedentary lifestyle. It is possible that increased physical activity and a decrease in body weight may be of benefit in the prevention of excess body-fat percent and CAD.
Received April 1, 1998. Accepted December 1, 1998.
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REFERENCES |
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This article has been cited by other articles:
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  M.-K. Wu, C.-K. Wang, Y.-M. Bai, C.-Y. Huang, and S.-D. Lee Outcomes of Obese, Clozapine-Treated Inpatients With Schizophrenia Placed on a Six-Month Diet and Physical Activity Program Psychiatr Serv, April 1, 2007; 58(4): 544 - 550. [Abstract] [Full Text] [PDF]
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 S. Calling, B. Hedblad, G. Engstrom, G. Berglund, and L. Janzon Effects of body fatness and physical activity on cardiovascular risk: Risk prediction using the bioelectrical impedance method Scand J Public Health, December 1, 2006; 34(6): 568 - 575. [Abstract] [PDF]
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