Human adaptations to diet: Biological and cultural coevolution.

Modern humans evolved in Africa some 200,000 years ago, and since then, human populations have expanded and diversified to occupy a broad range of habitats and use different subsistence modes. This has resulted in different adaptations, such as differential responses to diseases and different abilities to digest or tolerate certain foods. The shift from a subsistence strategy based on hunting and gathering during the Palaeolithic to a lifestyle based on the consumption of domesticated animals and plants in the Neolithic can be considered one of the most important dietary transitions of Homo sapiens. In this text, we review four examples of gene-culture coevolution: (i) the persistence of the enzyme lactase after weaning, which allows the digestion of milk in adulthood, related to the emergence of dairy farming during the Neolithic; (ii) the population differences in alcohol susceptibility, in particular the ethanol intolerance of Asian populations due to the increased accumulation of the toxic acetaldehyde, related to the spread of rice domestication; (iii) the maintenance of gluten intolerance (celiac disease) with the subsequent reduced fitness of its sufferers, related to the emergence of agriculture and (iv) the considerable variation in the biosynthetic pathway of long-chain polyunsaturated fatty acids in native populations with extreme diets.

Association between lifestyle features and obesity phenotypes in adults from the Basque Country (Spain).

Lifestyle is related to the risk of obesity, but the relationship between different lifestyle features and obesity phenotypes remains unclear. This study analysed the association between different lifestyle features (eating habits, activity, sleep patterns, and tobacco and alcohol consumption), and four obesity phenotypes (overall and abdominal obesity, distribution and percentage of fat). The sample included 521 adults aged between 18 and 70 years. A multiple logistic regression model was used, controlling for sex, age and socioeconomic status. The duration of the main meal was inversely associated with overall and abdominal obesity (p < 0.01) whereas the number of meals was positively associated (p < 0.05). Regular sport practice and duration were negatively associated with all obesity phenotypes (p < 0.01), while watching television showed positive associations. Walking was inversely related to overall and abdominal obesity (p < 0.01), whereas sleep quality was positively associated with both phenotypes. Former smokers showed a positive relationship with both abdominal obesity (p = 0.021) and fat mass distribution (p = 0.002), and the number of cigarettes were positively related with all obesity phenotypes (p < 0.01), except with fat distribution. Alcohol consumption was inversely related with an excessive adiposity (p = 0.030), while occasional drinking was negatively related with overall obesity and an excess of fat. In conclusion, few meals per day, a bad or regular quality of sleep, many hours spent watching television and a heavy cigarette consumption significantly increased the risk of various obesity phenotypes, while time spent at the main meal, walking and sport practice, and a moderate alcohol consumption were associated with a decreased risk.

Ideal body image for the opposite sex and its association with body mass index.

This research studied the preferences reported by women and men about their Ideal Body Image for the Opposite Sex (IBIOS), and its association with body mass index (BMI). It also analysed the preferences of each sex for a woman's ideal body image (W-IBI) and a man's ideal body image (M-IBI). A total of 450 participants aged 18-70 years with different weights were studied. Their IBIOS was assessed using standard figural stimuli. The sample was divided in four groups by sex and age (<45 years; ≥45 years). Sex and age differences in IBIOS, as well as sex differences in the preferences for a woman's ideal body image (W-IBI) and a man's ideal body image (M-IBI), were tested using a non-parametric Mann-Whitney U test. The association between IBIOS and BMI was analysed using Spearman's correlation. In all groups, the most chosen silhouette as IBIOS was number 4. In the under-45 years group, women chose bigger silhouettes for the opposite sex than men did (p<0.05). In this age group women chose as ideal smaller silhouettes for the female body than men did (p<0.01). In addition, women and men in the younger age group and with normal weight chose smaller silhouettes, while those who were overweight or obese selected larger silhouettes (p<0.001). Age was found to be a relevant factor in IBIOS preferences, and in the association between IBIOS and nutritional status as measured by BMI, which was only observed to be significant in the younger age group.

Association between self-perceived body image and body composition between the sexes and different age classes.

OBJECTIVES: The aim of this study was to investigate the association between self-perceived body image and body composition in the sexes and in different age classes. METHODS: The sample consisted of 632 young adults (238 men and 394 women; 22.8 ± 2.3 y of age), and 162 middle-aged and elderly adults (96 men and 66 women; 61.4 ± 7.6 y of age). The Williamson's figure scale was used to evaluate current body size. Anthropometric measurements (height, weight and waist, arm and calf circumferences) were taken, and body mass index was calculated. Specific bioelectrical impedance vector analysis was applied to evaluate body composition. RESULTS: The findings suggest that in both age classes, current body size was positively correlated with weight, body mass index, and vector length, indicative of the percentage of fat mass, but not with phase angle, indicative of the intracellular/extracellular water ratio and a proxy of muscle mass. The association was similar between men and women, but clearer in women. Confidence ellipses confirmed the strong association between the silhouettes and adiposity. CONCLUSION: The Williamson's figure scale silhouettes appear to be a suitable technique to screen for adiposity in epidemiologic studies and for routine applications.

Body image in relation to nutritional status in adults from the Basque Country, Spain.

The aim of this research was to analyse variation in body image perception and satisfaction by age, sex and nutritional status in an adult sample from the Basque Country, Spain. A case-control study was performed for 227 women and 178 men aged 18-70 years. Stunkard's silhouettes were used to evaluate Current Body Image (CBI) and Ideal Body Image (IBI), as well as dissatisfaction and inconsistency scores. Nutritional status was assessed following the WHO criteria for BMI in an adult population. The sample was divided into four groups based on sex and age (early adulthood <45 years, and middle/older adulthood ≥45 years). The Mann-Whitney U test was employed to evaluate sex and age differences, and the Gamma coefficient to assess the association between body image variables and nutritional status. Significant age differences in CBI (p<0.05) and sex differences in IBI (p<0.001) were detected. Both variables showed a positive association with BMI (p<0.01), which indicates that BMI is a biological characteristic related to body image satisfaction and influences participants' perception of themselves. Dissatisfaction scores showed that both sex and age differences (p<0.05) were negatively associated with BMI (p<0.001). Only participants ≥45 years presented sex differences in inconsistency scores (p<0.05); this variable was associated with BMI in women (p<0.01). Preferences in body image showed sexual dimorphism, with women preferring thinner bodies than men - a pattern observed in many Western populations - linked in part to sociocultural pressures. Women were more dissatisfied with their bodies than men; a higher dissatisfaction was observed in older relative to younger participants. The results confirm the association between nutritional status and body size perception and satisfaction, but also the relationship between nutritional status and the reliability with which women can classify themselves; in men, this relationship was not as clear.

Contribution of obesity associated genetic variants to anthropometric somatotype components.

The somatotype is a useful method in the analysis of body morphology but no study has identified genetic variants associated with its components. The aim of this study is o replicate the association of 21 SNPs with obesity and to explore their association with the somatotype components, in a sample from the Basque Country (Spain). A case-control study was performed in 472 adults from 18 to 79 years old. A literature search was conducted in PubMed to select genetic variants associated with obesity in European derived populations. After the quality control of the chosen variants, 21 SNPs were finally used to conduct association analyses. Logistic and linear regressions implemented in PLINK (v1.07) were used to assess the association between SNPs and the somatotype. Two genetic variants (rs925946 in BDNF and rs10146997 in NRXN3) showed a significant association with endomorphy (p < 0.01) while rs10146997 (in NRXN3) and rs9939609 (in FTO) were associated with mesomorphy (p < 0.01). rs925946 (in BDNF), rs10146997 (in NRXN3), rs9939609 (in FTO) and rs4776970 (in MAP2K5) were associated with ectomorphy (p < 0.05). In conclusion, four genetic variants (in or near BDNF, NRXN3, MAP2K5 and FTO) contribute to body shape and composition in the analysed sample.