BMI Class Research Articles

Underweight in Ski Jumping: The Solution of the Problem

Underweight is becoming increasingly prevalent in many sports. Among world class ski jumpers, the body mass index BMI has decreased by 4 units since 1970. The BMI ignores different body properties of individuals. Particular care should be taken in groups with unusual leg length to avoid classifying them inappropriately as thin or overweight (WHO). The improved measure MI (mass index) for relative body weight overcomes this shortcoming. Anthropometric data of ski jumpers was collected during the Olympic Games in Salt Lake City (2002; participation 81 %, n = 57), during the Summer Grand Prix in Hinterzarten (2000; participation 100 %, n = 92), and during the World Cup in Planica (2000; n = 56). The BMI and the MI were determined. The MI considers the individual leg length: A person with longer legs than average has an MI > BMI, and vice versa: MI = 0.28 m/s2 (m: mass in kg, s: sitting height in meters). BMI classes of ski jumpers in the season 2004/2005 were calculated from their official individual ski length limitation which is a function of their BMI. BMI means were 19.84 in Planica, 19.58 in Hinterzarten, and 19.43 kg m(-2) in SLC. Lowest BMI was 16.4 kg m(-2). The percentage of underweight ski jumpers (BMI < 18.5 kg m(-2)) decreased from 22.8 % at the Olympic Games 2002 to 8.7 % in the season 2004/2005 due to the new ski jumping regulations. The ratio s/h = C (s = sitting height, h = height, C = cormic index) ranged from 0.49 to 0.57. Accordingly, the MI values (which are leg length corrected BMI values according to MI = BMI (C /C) (k) with k = 2 and C = 0.53) deviated remarkably from BMI values. For the 49 cases with BMI or MI or both below 18.5 kg m(-2), the classification to be underweight or not changed in 69 % when the MI was used instead of the BMI. Underweight or overweight is not only a question of cut-off points; the measure used determines the classification accuracy. A substantial improvement of weight analyses in sports medicine, public health, and general medicine as well can be obtained by using the MI instead of the BMI.

Obesity and Sexual Quality of Life

Reduced sexual quality of life is a frequently reported yet rarely studied consequence of obesity. The objectives of this study were to 1) examine the prevalence of sexual quality-of-life difficulties in obese individuals and 2) investigate the association between sexual quality of life and BMI class, sex, and obesity treatment-seeking status. Subjects consisted of 1) 500 participants in an intensive residential program for weight loss and lifestyle modification (BMI = 41.3 kg/m2), 2) 372 patients evaluated for gastric bypass surgery (BMI = 47.1 kg/m2), and 3) 286 obese control subjects not seeking weight loss treatment (BMI = 43.6 kg/m2). Participants completed the Impact of Weight on Quality of Life-Lite, a measure of weight-related quality of life. Responses to the four Sexual Life items (assessing enjoyment, desire, performance, and avoidance) were analyzed by BMI, sex, and group. Higher BMI was associated with greater impairments in sexual quality of life. Obese women reported more impairment in sexual quality of life than obese men for three of four items. Gastric bypass surgery candidates reported more impairment in sexual quality of life than residential patients and controls for most items. In general, residential patients reported levels of impairment greater than or equal to controls. Obesity is associated with lack of enjoyment of sexual activity, lack of sexual desire, difficulties with sexual performance, and avoidance of sexual encounters. Sexual quality of life is most impaired for women, individuals with Class III obesity, and patients seeking gastric bypass surgery.

Nutritional surveillance in Tuscany: maternal perception of nutritional status of 8-9 y-old school-children.

Overweight and obesity in the developmental age has become a public health problem. For this reason, prevention projects must be developed in advance with the aim to involve not only children, but their parents as well. Our objective is to evaluate the accuracy of the mothers' perceptions of adolescent nutritional status. Cross-sectional study. We selected a statistical sample of 3,076 subjects (1,583 males, 1,493 females), 8-9 y-old school-children of 164 3rd-grade elementary school classes from throughout Tuscany, as well as their mothers. The mothers' information was gathered via self-administered questionnaires, while the children were given an eating behaviour survey under the supervision of qualified personnel. Mothers' education level (self-reported) height and weight were collected; children's height and weight were measured. The former were asked how they perceived their children's body image. A correlation exists between the mothers' perceptions of the nutritional state of their children via the silhouettes and the BMI classes of the children, which is equal to 80% with a kappa-Cohen for agreement equal to 0.58 (SE = 0.02; P < 0.0001). However, no correlation exists between the mothers' responses to the question "In your opinion, is your child ...?" and the child's actual BMI class (the exact percentage correlation is equal to 75%, with a kappa-Cohen for agreement equal to 0.43 SE = 0.014; P < 0.0001). Mothers have an accurate perception of the nutritional status of their children, correctly choosing the silhouette that corresponds to the child's BMI profile without variation by gender. We can assume that mothers in our sample have a good concept about healthy nutritional status.

Should Diabetes Be Considered a Coronary Heart Disease Risk Equivalent?

The purpose of our study was to confirm or refute the view that diabetes be regarded as a coronary heart disease (CHD) risk equivalent and to test for sex differences in mortality. This was a prospective cohort study of 7,052 men and 8,354 women aged 45-64 years from Renfrew and Paisley, Scotland, who were first screened in 1972-1976 and followed for 25 years. All-cause mortality was calculated as death per 1,000 person-years. A Cox proportional hazards model was used to adjust survival for age, smoking habit, blood pressure, serum cholesterol, BMI, and social class. There were 192 deaths in 228 subjects with diabetes and 2,016 deaths in 3,076 subjects with CHD. The highest mortality was in the group with both diabetes and CHD (100.2 deaths/1,000 person-years in men, 93.6 in women) and the lowest in the group with neither (29.2 deaths/1,000 person-years in men, 19.4 in women). Men and women with diabetes only and CHD only formed an intermediate risk group. The adjusted hazard ratio (HR) for CHD mortality in men with diabetes only compared with men with CHD only was 1.17 (95% CI 0.78-1.74; P = 0.56). Corresponding HR for women was 1.97 (1.27-3.08; P = 0.003). Diabetes without previous CHD carries a lifetime risk of vascular death as high as that for CHD alone. Women may be at particular risk. Our data support the view that cardiovascular risk factors in diabetes should be treated as aggressively as in people with CHD.

Impaired response of cardiac autonomic nervous system to glucose load in severe obesity

Objective This study was undertaken to further analyze the response of the cardiovascular autonomic nervous system (ANS) to changes in plasma insulin concentration induced by an oral glucose load. We hypothesized that, as a consequence of insulin resistance, an inability of insulin to increase the sympathetic modulation of heart rate (HR) and blood pressure (BP) would be observed in normotensive obese patients. Methods We used spectral analysis to measure simultaneously the short-term variability of HR and BP in 23 never-obese subjects and in 70 normotensive overweight or obese patients subdivided into 3 subgroups: (1) overweight group (body mass index [BMI], 25-29.9 kg/m 2), n = 23; (2) class I-II obese group (BMI, 30-39.9 kg/m 2), n = 23; (3) class III obese group (BMI, ≥40 kg/m 2), n = 23. Results Oral glucose ingestion and the related increased insulinemia caused significant changes in the indices of sympathetic modulation (low-frequency [LF] power and LF/high-frequency ratio) of both HR and BP in normal weight, overweight, and obese subjects. However, the LF increments gradually decreased with the BMI classes, suggesting that sympathetic nervous system modulation in these subjects may be insulin-resistant. Conclusion Obesity could develop resistance to the sympatho-excitatory effects of insulin that might play a role in the etiology of obesity. Spectral analysis of BP and HR can be used in research to evaluate the reactivity of the sympathetic nervous system in a manner that represents another feature of the obesity/insulin-resistance syndrome.

The new BMI criteria for asians by the regional office for the western pacific region of WHO are suitable for screening of overweight to prevent metabolic syndrome in elder Japanese workers.

Obesity occurs less frequently in Japanese than in various other ethnic populations. A person with abnormal glucose tolerance is often found to have one or more of the other cardiovascular disease risk factors, such as obesity, hypertension and hyperlipidemia. This clustering has been labeled as metabolic syndrome (WHO, 1998). It was suggested that Japanese, categorized as having normal weight (BMI of less than 25.0), as defined by the WHO (2000), have an increasing tendency toward metabolic syndrome. Our objective was to analyze metabolic syndrome in "Overweight" with BMI of 23.0-24.9 in Japanese workers, and to assess the suitability for Asians of the Regional Office for the Western Pacific Region of WHO criteria pertaining to obesity (WPRO criteria, 2000). We conducted a cross-sectional study in the workplace setting and investigated the relationship between BMI classification based on WPRO criteria and metabolic syndrome by gender and age group (18-44 yr vs. 45-60 yr). Three hundred seventy-nine men and 432 women Japanese workers participated in this study. BMI were categorized as 20% "Overweight" (23.0-24.9 BMI), 20% "Obese I" (25.0-29.9 BMI) and 2% "Obese II" (over 30.0 BMI), based on WPRO criteria. Graded increases in BMI were positively associated with body fat percentage, waist circumference, hip circumference and waist/hip ratio in both genders and age groups. A progressively increasing BMI category in the elder group aged 45-60 yr in both genders was positively related with parameters constituting metabolic syndrome. Graded increases in BMI classes in elder workers based on WPRO criteria were positively associated with prevalence of metabolic syndrome, and "Overweight" elder women had significantly higher prevalence of metabolic syndrome. The present investigation, based on the increasing risks of "Overweight" with a BMI of 23.0-24.9, suggests that WPRO criteria are suitable for Japanese workers aged over 45 yr.

Assessment of global coronary heart disease risk in overweight and obese African-American women.

To examine, with the use of national guidelines, coronary heart disease (CHD) risk with increasing BMI for primary prevention in urban African-American women. Participants were recruited for CHD risk factor screening from 20 churches as part of a larger study of nutrition and fitness (Project Joy). All participants had a demographic, smoking and medical history assessment, and the following measurements were taken: weight, height, waist circumference, blood pressure, lipid levels, and glucose. Three methods of defining risk, the Framingham Point Scoring System, a count of risk factors, and the presence of the multiple metabolic syndrome, based on the National Cholesterol Education Program Adult Treatment Panel III Report and BMI classes established by the Clinical Guidelines, were used. A total of 396 women were eligible. Participants were 40 to 80 years of age and had marked excess prevalence of overweight and obesity (84%); 55% were obese. There was a linear increase in risk factors as BMI increased. Lipids did not differ significantly among BMI classifications. Seventeen percent of women had multiple metabolic syndrome. Eight percent and 16% of women in the normal and overweight BMI classes, respectively, had two or more modifiable risk factors. There was no difference in number of modifiable risk factors among the obese classes. The Framingham Point Scoring System assigned a <10% risk of a hard CHD event in 10 years to 97% of the women. National risk assessment guidelines for primary prevention of CHD may not be adequate for overweight and obese urban African-American women and require further study.

Impedance vector distribution by sex, race, body mass index, and age in the United States: standard reference intervals as bivariate Z scores

Bioelectrical impedance measurements were collected in the Third National Health and Nutrition Examination Survey (NHANES III), but their results have not been published. In the NHANES III population, resistance (R) and reactance (Xc) values at 50-kHz frequency were obtained with a Valhalla Scientific meter (model 1990B; San Diego, CA, USA). The RXc graph method was used to identify bivariate pattern distributions of mean vectors (95% confidence ellipses by sex, race, age, and body mass index [BMI]), and individual impedance vectors (50%, 75%, and 95% tolerance ellipses). Data from 10 222 adults (5261 men and 4961 women) formed 90 four-way classification groups, with two sexes, three races or ethnicities (non-Hispanic white, non-Hispanic black, Mexican American), five age classes (20–29, 30–39, 40–49, 50–59, and 60–69 y), and three BMI classes (19–24.9, 25–29.9, and 30–34.9 kg/m2). Sex, race or ethnicity, BMI and age, in decreasing order, influenced the vector distribution pattern. Mean vectors in women were significantly longer than those in men. Within each sex, the mean vector of non-Hispanic white subjects was shorter and with a smaller phase angle than that of corresponding BMIs from the two other race/ethnic populations. Tolerance ellipses were calculated from sex- and race-specific reference populations 20 to 69 y old and 19 ≤ BMI < 30 kg/m2 (8022 subjects, 4226 men and 3796 women). After transformation of impedance vector components into bivariate Z scores (standardized deviates, as differences from the mean divided by the standard deviation of the reference population), we constructed one standard, reference, RXc-score graph (50%, 75%, and 95% tolerance ellipses) that can be used with any analyzer in any population. The pattern of impedance vector distribution and reference bivariate intervals for the individual impedance vector are presented for comparative studies (free software at E-mail: apiccoli@unipd.it).

The G-308A variant of the Tumor Necrosis Factor-alpha (TNF-alpha) gene is not associated with obesity, insulin resistance and body fat distribution.

BackgroundTumor Necrosis Factor-α (TNF-α) has been implicated in the pathogenesis of insulin resistance and obesity. The increased expression of TNF-α in adipose tissue has been shown to induce insulin resistance, and a polymorphism at position -308 in the promoter region ofTNF-α has been shown to increase transcription of the gene in adipocytes. Aim of this study is to investigate the role of the G-308A TNFα variant in obesity and to study the possible influence of this mutation on body fat distribution and on measures of obesity (including Fat Free Mass, Fat Mass, basal metabolic rate), insulin resistance (measured as HOMAIR), and lipid abnormalities. The G-308A TNFα polymorphism has been studied in 115 patients with obesity (mean BMI 33.9 ± 0.5) and in 79 normal lean subjects (mean BMI 24.3 ± 0.3).MethodsThe G-308A variant, detected by PCR amplification and Nco-1 digestion, determines the loss of a restriction site resulting in a single band of 107 bp [the (A) allele].ResultsThe (A) allele frequencies of the G-308A TNFα polymorphism were 13.1% in the obese group and 14.6% in the lean subjects, with no significant difference between the two groups. Furthermore, no association was found with BMI classes, body fat distribution, HOMAIR, and metabolic abnormalities.ConclusionsOur study did not detect any significant association of the G-308A TNFα polymorphism with obesity or with its clinical and metabolic abnormalities in this population. Our data suggests that, in our population, the G-308A TNFα polymorphism is unlikely to play a major role in the pathogenesis of these conditions.

Blood pressure levels and hypertension status among ethnic groups in England.

The prevalence of cardiovascular disease and hypertension show wide variability among different ethnic groups in the UK. We combined data collected annually between 1991-1996 in the Health Surveys for England--nationwide surveys that provide information on the health status in a representative sample of the population living in England, to compare blood pressure (BP) levels, hypertension rates (systolic BP > or = 160 mm Hg or diastolic BP > or = 95 mm Hg, or those on antihypertensive medication), hypertension treatment and control rates in people of white, black (combining black-Caribbean, black-African and black-other), and South Asian origin (combining Indians, Pakistanis and Bangladeshis). Analyses were stratified into two age groups, 16-39 (younger) and > or = 40 years (older), but were focused on older adults (30,619 whites, 295 blacks and 529 South Asians). Age-adjusted mean BP levels and hypertension rates of older adults were highest among blacks, while South Asian men showed BP levels and hypertension rates similar to black men and South Asian women had mean BP levels and hypertension rates similar to white women. After controlling for age, BMI, smoking, alcohol consumption, and social class the odds ratio (OR) of being hypertensive among older adults was higher in black men (OR 2.0; 95% CI 1.4, 2.9; P < 0.001); black women (OR 1.7; 95% CI 1.2, 2.5; P < 0.01); and South Asian men (1.9; CI 1.4, 2.4; P < 0.001), than in their white counterparts. Among those studied with hypertension, treatment rates were highest among black men and women. Among those on antihypertensive medication, the odds of having BP controlled (SBP < 160 mm Hg and DBP < 95 mm Hg) did not differ among the three groups of older men but was reduced in older South Asian women, compared with white women.

Epidemiology of eating behaviour and weight distribution in 14– to 19‐year‐old Swiss students

A sample consisting of 1944 Swiss students of both sexes was investigated with regard to distribution over weight categories based on BMI age percentiles and eating behaviour (EAT-26) in relation to age, sex and socio-economic status (SES). In addition, the relationship between BMI and Eating Attitudes Test scores was analysed. More subjects than expected were found to be in the obese weight categories. No clear effect of age and sex on the distribution of the sample across the five BMI classes was observed. There was an inverse relationship between BMI and socio-economic status. On the EAT scale girls scored twice as high as boys. Age had no effect on the EAT scores in females, although it did in males. Socio-economic status and EAT scores were inversely associated. Three risk categories based on the EAT scores were described: EAT 0-9 = no risk (77.5% girls, 93.0% boys), EAT 10-19 = low risk (14.1% girls, 5.5% boys), and EAT > or = 20 = high risk (8.3% girls, 1.5% boys). With regard to both aspects, weight and eating behaviour, female students showed more disturbed eating behaviour and fewer instances of deviation from normal weight. In male subjects there were more deviations from normal weight than instances of disturbed eating behaviour.

Relationship of menstrual irregularities to BMI and nutritionalstatus in adolescent girls

Objective: To evaluate the effect of Body Mass Index and nutritional status on the menstrual pattern in adolescent girls Methods: Four hundred one adolescent girls who attained menarche were selected from five schools in Hyderabad. The data was collected by trained medical undergraduate and postgraduates by interviewing adolescent school girls using a pre-designed pre-tested questionnaire. BMI was calculated using the formula: BMI (kg/m2) = Weight (kg) / Height 2 (m2). Hb was estimated by Sahlis method using a haemoglobinometer. Data was analyzed using SPSS 11.0. Results : The mean age of the girls was 14.96 +/- 1.5 years. Three hundred and five (76%) of the girls had a normal menstrual cycle, twenty-eight (7 %) had frequent periods, fifty-two (13%) had infrequent periods and sixteen (4%) of the girls had totally irregular cycles and a pattern could not be determined. Three hundred and five (76%) of girls had a normal menstrual flow, sixty-eight (17%) had heavy flow and twenty-eight (7%) had scanty flow. One hundred fifty two (38%) of girls complained of premenstrual symptoms. Two hundred thirty one (60%) girls were clinically anemic. Two hundred and seventy seven (69%) had a BMI between 18.5 - 24.9 kg/m2. One hundred and eight (27%) were underweight with a BMI of 14 – 18.49kg/m2, while sixteen (4%) were overweight with BMI 25 – 29.99 kg/m2. A statistically significant relationship was found between BMI and social class (P<0.001) and BMI and menstrual pattern P<0.001). Conclusion : The study concludes that a majority of the girls had clinically obvious nutritional deficiency diseases. Out of the four hundred and one girls who were checked, two hundred thirty one were found to be anemic. Majority of the girls (84%) had a normal menstrual pattern, normal BMI and attained menarche before the age of 16. Overweight girls had infrequent periods.