Association between personal background and obesity in adults from the Basque Country (Spain)

Title Association between personal background and obesity in adults from the Basque Country (Spain) Authors María Eugenia Ibáñez-Zamacona1,2, Aline Jelenkovic2, Esther Rebato2 1Department of Pharmacy and Food Science, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), Bilbao, Spain. 2Department of Genetics, Physical Anthropology and Animal Physiology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Bilbao, Spain. Corresponding author: Esther Rebato Department of Genetics, Physical Anthropology and Animal Physiology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Bilbao, Spain. Email: esther.reba[email protected] Running title Association between personal background and obesity Número de Tablas y Figuras 4 Tablas This is the accepted manuscript of the article that appeared in final form in Revista Española de Antropología Física 46 : 29-39 (2022), which has been published in final form at https://seaf.es/index.php/revista-reaf/235-volumen-46-2022. © 2022 Sociedad Española de Antropología Física under CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Abstract Obesity is a complex phenotype involving an excessive amount of body fat that may impair health. Both genes and environment are involved in the development of obesity, with family history being considered an important risk factor. The aim of this study was to determine the degree of association of family history of obesity, obesity-related diseases and physical health perception with different obesity indicators, in a sample of adult population living in the Basque Country (Spain). The study was conducted on 521 individuals (318 women and 203 men), aged from 19 to 70 years. Body mass index, waist circumference, waist-hip ratio and the percentage of fat mass were taken into account as obesity indicators. Multiple logistic regressions were used to assess the relationship between the four obesity indicators and the personal background variables. The strength of the association between pairs of variables was expressed in terms of Odds Ratios. The results confirmed a positive and significant association between personal background and different obesity indicators, although the magnitude of the associations was different for each obesity measure. A family history of obesity, especially having obese first-degree relatives, was a clear risk factor for obesity development (overall, abdominal and excess of fat); however, fat distribution was associated with obesity-related diseases. A bad perception of physical health condition was strongly related with all indicators of obesity, especially with body mass index and excess of fatness. Key words Family history of obesity, Obesity-related diseases, Physical health perception, Obesity indicators Resumen La obesidad es un fenotipo complejo que conlleva una cantidad excesiva de grasa corporal que puede perjudicar la salud. Tanto los genes como el ambiente están implicados en el desarrollo de la obesidad, considerándose a los antecedentes familiares como un importante factor de riesgo. El objetivo de este estudio fue determinar el grado de asociación de los antecedentes familiares de obesidad, las enfermedades relacionadas con la obesidad y la percepción de salud física con diferentes indicadores de obesidad, en una muestra de población adulta residente en el País Vasco (España). El estudio se realizó en 521 individuos (318 mujeres y 203 hombres) de entre 19 y 70 años. Como indicadores de obesidad se consideraron el índice de masa corporal, el perímetro de la cintura, la relación cintura-cadera y el porcentaje de masa grasa. Se usaron regresiones logísticas múltiples para evaluar la relación entre los pares de variables; el grado de asociación se expresó en términos de Odds Ratios. Los resultados confirman una asociación positiva y significativa entre los antecedentes personales y la obesidad, aunque los valores de las asociaciones fueron diferentes para cada indicador. Los antecedentes familiares de obesidad, especialmente tener familiares obesos de primer grado, suponen un factor de riesgo para la obesidad (general, abdominal y exceso de grasa), aunque la distribución de grasa no se asoció con esta variable, sino con las enfermedades relacionadas con la obesidad. Una mala percepción del estado de salud se asoció con todos los indicadores de obesidad, especialmente con el índice de masa corporal y el exceso de adiposidad. Palabras clave Historia familiar de obesidad, Enfermedades relacionadas con la obesidad, Percepción de la salud física, Indicadores de obesidad. Introduction Obesity, defined as an excessive accumulation of body fat that may impair health (WHO, 2000), is a complex phenotype affected by behavioural and environmental factors, but also by genetic and epigenetic ones (Thaker, 2017; Rohde et al., 2019; Diels Vandem Berge and Wan Hul, 2020). Common obesity is a widespread condition in westernized countries; however, its incidence is variable between and within populations (Rebato, 2021). Genetic profile (including family background), sex, age, and environmental factors such as lifestyle, socioeconomic status (SES) or psychological circumstances, among others, are considered key elements in obesity development, as they are involved in energy balance and fat store/storage. A substantial genetic contribution to obesity risk has been demonstrated by different heritability studies based on nuclear families and twins, with heritabilities (h2) of Body Mass Index (BMI) ranging from 47% to 90% in twin studies and 20% to 50% in family ones (Elks et al. 2012; Feng, 2016). In addition, near 80 genome-wide linkage studies have identified more than 300 chromosomal loci with suggestive evidence of linkage to obesity traits (see review by Loos and Yeo, 2022). Family history thus seems to confer a predisposition to obesity, although the interaction between genes and environment must be taken into account; sometimes the lifestyle of parents can be just as important as their genetics in “passing on” the risk of obesity to their children (Bahreynian et al., 2017). Obesity is associated with several comorbidities, such as type 2 diabetes, cardiovascular disease, kidney diseases, cancer in at least 13 anatomical locations, musculoskeletal disorders and infections (Avgerinos et al., 2019; Sawadogo et al., 2021; Kivimäki et al., 2022); in this latter case, as evidenced during the recent COVID pandemic (Barreto Paravidino et al., 2022). In addition, people with obesity may experience discrimination (so-called "obesity or weight stigma"), which has an impact on their psychological and physical health, as well as on their self-esteem and perception of both their body image and health status (Puhl and Heuer 2010; Latner and Stefano, 2016; Ibáñez-Zamacona, Poveda and Rebato, 2020, 2021). The aim of this study was to determine the degree of association of the personal background (family history of obesity, obesity-related diseases and physical health perception) with different obesity indicators, in adults of both sexes living in the Basque Country (Spain). Material and methods Sample The study was conducted on 521 individuals (318 women and 203 men), aged from 19 to 70 years, living in the Basque Country (Spain). A large percentage of the sample (77.7%) was born in the Basque Country, as were their parents (52%); the rest are from other Spanish regions, mainly Castile and Leon (20.8%). In terms of socioeconomic status (SES), and based on educational and professional levels, the sample was considered to be middle class (for details see Ibáñez Pérez-Zamacona, 2017). Both individuals with and without obesity were well represented (case-control study design). In accordance with the Helsinki Declaration, written informed consent was obtained from all participants in the study. The research was approved by the Ethics Committee for Research Involving Human Beings of the University of the Basque Country (UPV/EHU). Obesity indicators and personal background Height, body weight, waist and hip circumferences (WC, HC), and four skinfolds (biceps, triceps, subscapular and suprailiac) were taken following standard criteria (Lohman, Roche and Martorell, 1988) by trained personnel (M.E.I.). Four obesity indicators were considered: BMI (kg/m2) as an index of overall obesity, waist circumference (WC, cm) as an estimator of abdominal fat (i.e. internal fat deposits), waist-hip ratio (WHR=WC/HC) as a measure of fat distribution, and fat mass percentage (FM%) as an evaluator of adiposity. FM% was calculated by using Siri's (1961) equation based on body density (D) obtained from the general equation of Durnin and Womersley (1974), taking into account sex and age. For the first three obesity indicators, the cut-off points were the established by the WHO (2000, 2011), and for FM% the criteria of the Spanish Society for the Study of Obesity (Campillo et al., 2000). Based on these cut-off points, the obesity indicators were dichotomised for statistical treatment as follows: a) Obesity (BMI≥30 kg/m2) vs. non-obesity (BMI<30 kg/m2); b) Abdominal obesity (WC>88 cm in women and >102 cm in men) vs. no abdominal obesity (WC≤ 88 cm in women, and ≤102 cm in men); c) Central fat distribution (WHR≥0.85 in women, and ≥0.90 in men) vs. peripheral fat distribution (WHR <0.85 in women, and <0.90 in men); d) Excess of fat (FM% >33% in women, and >25% in men) vs. no excess fatness (FM% between 20-33% in women, and between 12-25% in men). Personal background was collected by means of personal interview (M.E.I.), and included three variables with different categories each (eight in total): 1) Family history of obesity that indicates if the participant has any relative with obesity and its degree of relatedness. Categories: No, 1st degree, 2nd degree. 2) Obesity-related diseases that indicate if the participant has or does not have any type of obesity-related disease, namely, type 2 Diabetes, hypertension, hypercholesterolemia, cardiovascular and/or respiratory diseases. Categories: No, Yes. 3) Physical health perception that indicates how the participant perceives his/her physical health condition. Categories: Good, Regular, Bad. Data analysis The number and percentage (%) of individuals with overall obesity (BMI≥30 kg/m2) as well as BMI mean (M) and standard deviation (SD) were calculated for each category of the three qualitative variables (personal background), separately for sex and two age groups (<45 years and ≥45 years). Data were tested for normality and homoscedasticity using the Kolmogorov-Smirnov test (n>50), or the Shapiro-Wilk test (n≤50) and the Levene test. Multiple logistic regressions were used to assess the relationship between the four obesity indicators (dependent variables) and the background variables (independent ones). Age, sex and socioeconomic status (SES) were used as covariates to control for potential confounding effects. The strength of the association between pairs of variables was expressed in terms of Odds Ratios (OR), which measures the effect size. Bonferroni correction for multiple comparisons was calculated (p< 0.0007), but the significance threshold was set at p<0.05, due to the sample size and the conviction that this correction is too conservative. Results Tables 1 to 3 show the descriptive statistics for the three personal background variables in women and men and in both age groups, in addition to the corresponding BMI mean and SD. All individuals whose first-degree relatives were obese had a higher frequency of obesity than in the other two categories considered for family history of obesity (Table 1). Regarding sex and age, obesity percentages were lower in women (58.3%) than in men (60.6%) in the oldest age group, as well as in the <45 years group (34% and 40% and in women and men, respectively). In individuals over 45 years of age with obese second-degree relatives, it is also worth noting the high frequency of obesity (50% in women and 30% in men). The mean BMI was higher in individuals whose first-degree relatives were obese, with values of 32.5 and 32.7 for women and men in the age group ≥45 years, and of 29.6 (women) and 30.9 (men) for those under 45 years of age (Table 1). As shown in Table 2, 50% of women and 60% of men under 45 years of age who had some type of obesity-related disease were obese; for the same category, but in the age group ≥45 years, the percentages of obesity were also high, especially in women (69.8%). Among the individuals over 45 years of age who did not report obesity-related diseases, it is worth noting a significant percentage of obese (35.2% of women and 33.3% of men). BMI values were very high in individuals who reported having some type of obesity-related disease, with values ranging from 40.2 (the maximum) to 31.3 (the minimum), compared to those who reported none, whose BMI ranged from 26.4 to 29 (Table 2). Table 3 shows that a large percentage of women and men that reported to have a bad physical health perception were obese (54.8% of women and 64.7% of men <45 years, and 74.4% of women and 68.4% of men ≥45 years); in this category BMI was higher than in the other two categories, with BMI ranging from 33.6 to 35.8 (women) and 37.5 to 34.0 (men), depending on the age group. There were also high frequencies of obesity among women and men older than 45 years who had a good (28.6% to 38.7%) or regular (37.5% to 40.8%) perception of their physical health (Table 3). Individuals with obese first-degree relatives had between 2.19 and 3.96 times more risk to be obese compared with those who did not have obese relatives (Table 4); the associations between this variable (family history of obesity) and three obesity indicators were highly significant (p<0.001 for BMI and WC; p<0.01 for FM%). Based on BMI and waist circumference (WC), the risk for obesity was almost 2 fold higher in Individuals having obesity-related diseases (p<0.05 for both indicators) than in those free of diseases (Table 4). The risk was 3.44 fold higher in individuals with central fat distribution (WHR) compared with subjects free of diseases (p<0.001). A bad perception of the physical health was significantly associated with all obesity indicators. Among them, the one based on FM% had the higher association (OR=10.42, p<0.001), whereas the one based on WHR had the lowest one (OR=2.64, p<0.01). Discussion According to the obtained results, and in line with other studies (e.g. Neutzling, Taddei and Gigante, 2003; Ochoa et al., 2007; Fipps et al., 2022), a family history of obesity (i.e. close relatives with obesity) can be considered a risk factor for the development of obesity in the studied sample. In general, and irrespective of sex and age, individuals whose first-degree relatives were obese were more likely to be obese; having obese second-degree relatives was also associated with a higher risk, although only in the older age group and especially in women. However, a considerable proportion of obese women and men (mainly over 45 years of age) did not have a family history of obesity; this can indicates that “genes are not always destiny” (Veerman, 2011; Kim, 2019). Three of the four obesity indicators studied were significantly associated with having obese first-degree relatives; these individuals were between 2.19 and 3.62 times more likely to be obese. This relationship typically illustrates two underlying processes. 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