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PubMed1994

Adjusting milk intake for body size in early infancy.

Energy intake and expenditure are related to body size and body composition and therefore must be taken into consideration when comparing individuals. Previous work has typically expressed energy metabolism variables per kilogram body weight or per kilogram fat-free mass. However this may not remove the effect of body size entirely. In infancy milk volume intake is usually expressed in a similar manner which may not be entirely appropriate. The most appropriate method of expressing milk volume intake relative to body weight and fat-free mass was investigated in 20 normal breast-fed infants at 6 weeks of age. Regression analysis revealed that the relationship between milk intake and body weight could be adjusted for by expressing milk intake per kg0.68, and that the relationship between milk intake and fat-free mass could be adjusted for by expressing milk intake per kg0.54. These values are not significantly different to 0.50 which is the square root of body weight. It is suggested that in studies of energy metabolism in infancy the expression of milk intake per kg0.50 should be used as the most appropriate adjustment for removing the influence of body size upon milk intake, in the first few months of life.

Body Constitution↗
PubMed2007

Correlated responses to artificial body size selection in growth, development, phenotypic plasticity and juvenile viability in yellow dung flies.

Most life history traits are positively influenced by body size, whereas disadvantages of large body size are poorly documented. To investigate presumed intrinsic costs of large size in the yellow dung fly (Scathophaga stercoraria; Diptera: Scathophagidae), we established two replicates each of three body size laboratory selection lines (small, control and large; selection on males only), and subjected flies of the resulting extended body size range to various abiotic stresses. Response to selection was symmetrical in the small and large lines (realized h(2) = 0.16-0.18). After 24 generations of selection body size had changed by roughly 10%. Female size showed a correlated response to selection on male size, whereas sexual size dimorphism did not change. Development time also showed a correlated response as, similar to food limited flies, small line flies emerged earlier at smaller body size. At the lowest larval food limit possible, flies of all lines emerged at the same small body size after roughly the same development time; so overall phenotypic plasticity in body size and development time strongly increased following selection. Juvenile mortality increased markedly when food was extremely limited, large line flies showing highest mortality. Winter frost disproportionately killed large (line) flies because of their longer development times. Mortality at high temperatures was high but size-selective effects were inconsistent. In all environments the larger males suffered more. Initial growth rate was higher for males and at unlimited food. Small line individuals of both sexes grew slowest at unlimited larval food but fastest at limited larval food, suggesting a physiological cost of fast growth. Overall, extension of the natural body size range by artificial selection revealed some otherwise cryptic intrinsic juvenile viability costs of large size, mediated by longer development or faster growth, but only in stressful environments.

Animal Nutritional Physiological Phenomena↗
PubMed2006

Quantitative trait loci for body size components in mice.

Do body size components, such as weights of internal organs and long bone lengths, with different functions and different developmental histories also have different genetic architectures and pleiotropic patterns? We examine murine quantitative trait loci (QTL) for necropsy weight, four long bone lengths, and four organ weights in the LG/J x SM/J intercross. Differences between trait categories were found in number of QTL, dominance, and pleiotropic patterns. Ninety-seven QTLs for individual traits were identified: 52 for long bone lengths, 30 for organ weights, and 15 for necropsy weight. Results for long bones are typically more highly significant than for organs. Organ weights were more frequently over- or underdominant than long bone lengths or necropsy weight. The single-trait QTLs map to 35 pleiotropic loci. Long bones are much more frequently affected in groups while organs tend to be affected singly or in pairs. Organs and long bones are found at the same locus in only 11 cases, 8 of which also include necropsy weight. Our results suggest mainly separate genetic modules for organ weights and long bone lengths, with a few loci that affect overall body size. Antagonistic pleiotropy, in which a locus has opposite effects on different characteristics, is uncommon.

Animals↗
PubMed2006

Agreement with satisfaction in adolescent body size between female caregivers and teens from a low-income African-American community.

OBJECTIVE: To describe body size satisfaction and agreement among low-income, urban, African-American adolescents, and female caregivers. METHODS: Two hundred and fifteen adolescent-caregiver pairs completed measures of demographics, anthropometrics, and body size satisfaction. RESULTS: Adolescent-caregiver agreement on body size satisfaction varied by body mass index (BMI) category. Among normal weight adolescents, 61% of adolescent-caregivers agreed that current body size was ideal. Among adolescents at risk for overweight, 38% of adolescent-caregivers agreed that current body size was ideal, and 38% were discordant with adolescents wanting to be thinner and caregivers satisfied with current body size. Among overweight adolescents, adolescent-caregiver agreement was 67%; 52% agreed the adolescent should be thinner and 15% agreed current body size was ideal. CONCLUSIONS: Body size satisfaction is related to BMI category for adolescents and caregivers, but adolescents have a lower threshold. Encouraging caregivers to elicit their adolescents' views on body size satisfaction may enable caregivers to support their adolescents in addressing weight-related issues.

Adolescent↗
PubMed1997

Body size and hip fracture risk in older women: a prospective study. Study of Osteoporotic Fractures Research Group.

PURPOSE: To determine the relationship between measures of body size and the risk of hip fracture in elderly women. PARTICIPANTS AND METHODS: The association between measures of body size and hip fracture risk was assessed in 8,011 ambulatory, nonblack women 65 years of age or older enrolled in the Study of Osteoporotic Fractures with measurements of total body weight, percent weight change since age 25, hip girth, lean mass, fat mass, percent body fat, body mass index, modified body mass index, and femoral neck bone mineral density (BMD) at the second examination. These 8,011 women were followed prospectively for incident hip fractures occurring after the second examination, which were confirmed by review of x-ray films. RESULTS: During an average of 5.2 years after the second examination, 236 (2.9%) women experienced hip fractures. Similar associations were observed between hip fracture risk and all measures of body size including total body weight, percent weight change since age 25, hip girth, lean mass, fat mass, percent body fat, body mass index, and modified body mass index. Women with smaller body size had a higher risk of subsequent hip fracture compared with those with larger body size, while women with average and larger body sizes shared similarly lower risks of subsequent hip fracture. For example, the incidence rate of hip fracture was 9.35 per 1000 woman-years in women in the lowest quartile of total weight compared with 4.63 per 1000 woman-years in women in the highest quartile of total weight (age-adjusted relative risk 1.93, 95% confidence interval (CI) 1.34 to 2.80), while rates of hip fracture among women in the second and third quartiles of total weight (5.22 and 4.32 per 1000 woman-years, respectively) were not significantly different from the rate among women in the highest quartile (P > 0.64). The increased risk of hip fracture among women of smaller body size remained after further adjustment for additional potential confounding factors including height at age 25, smoking status, physical activity, health status, estrogen use, and diuretic use. After further adjustment for femoral neck BMD, women with smaller body size were no longer at significantly increased risk of hip fracture compared with those with larger body size. For example, after adjustment for height at age 25, smoking status, physical activity, health status, estrogen use, and diuretic use, thin women had a 2.5-fold increase in the risk of hip fracture (multivariate relative risk 2.51, 95% CI 1.69 to 3.73) compared with the referent group composed of the heaviest women. After further adjustment for femoral neck BMD, the multivariate relative risk of hip fracture among thin women compared to heaviest women was 0.98 (95% CI, 0.64 to 1.50). CONCLUSION: Older women with smaller body size are at increased risk of hip fracture. This effect is because of lower hip BMD in women with smaller body size. Assessment of body size for prediction of hip fracture risk can be accomplished by measuring total body weight.

Aged↗
PubMed2003

Correlated evolution of conspicuous coloration and body size in poison frogs (Dendrobatidae).

Conspicuous coloration is often used in combination with chemical defenses to deter predators from attacking. Experimental studies have shown that the avoidance inducing effect of conspicuous prey coloration increases with increasing size of pattern elements and with increasing body size. Here we use a comparative approach to test the prediction from these findings, namely that conspicuous coloration will evolve in tandem with body size. In our analysis, we use a previously published mitochondrial DNA-based phylogeny and comparative analysis of independent contrasts to examine if evolutionary shifts in color pattern have been associated with evolutionary changes in body size in aposematic poison frogs (Anura: Dendrobatidae). Information on body size (snout to vent length) and coloration were obtained from the literature. Two different measures of conspicuousness were used, one based on rankings by human observers and the other based on computer analysis of digitized photographs. The results from comparative analyses using either measure of coloration indicated that avoidance inducing coloration and body size have evolved in concert in poison frogs. Results from reconstruction of character change further indicate that the correlated evolution of size and coloration has involved changes in both directions within each of the different clades of the phylogenetic tree. This finding is consistent with the hypothesis that selection imposed by visually guided predators has promoted the evolution of larger body size in species with conspicuous coloration, or enhanced evolution of conspicuous coloration in larger species.

Animals↗
PubMed1994

Black and white females' perceptions of ideal body size and social norms.

Different cultural norms and standards for appropriate female body size might contribute to the disparity in obesity rates between black and white adult females (46.0% and 24.6% respectively). The purpose of this study was to measure adolescents' perceptions of ideal size and social norms regarding female body size as well as adolescents' perceptions of significant others' evaluation and expectations of the adolescents' body size. Subjects included 437 adolescent girls (247 white and 190 black) aged 13 to 19 (x = 14.9, SD = .979) from six randomly selected public schools. The subjects, heights and weights were measured. Responses to a body image questionnaire and a series of nine female body drawings (arranged ordinally, 1 to 9, from thinnest to heaviest) were analyzed using the General Linear Model and Logistic Regression. The female body size considered ideal by black females was significantly larger than the size selected as ideal by white females (x = 3.47 and x = 3.13 respectively, p < 0.001). Black females were two times more likely than white females to describe themselves as thinner than other girls their age (O.R. = 2.01, 95% C.I. 1.34, 3.01) and seven times as likely to say that they were not overweight (O.R. = 7.08, 95% C.I. 3.72, 13.45). White females wanted to be a smaller size than they currently were and felt encouraged by significant others to lose weight or reduce their size. Black females did not indicate as great a desire as whites to be smaller and they tended to feel that their size was considered satisfactory by significant others. Only subjects from the low SES group perceived that significant others wanted them to gain weight. The differences between black and white subjects' beliefs and perceptions about body size norms may explain, in part, why heavier body weights persist in some cultural groups.

Adolescent↗
PubMed1991

Relationship of cardiac size to maximal oxygen uptake and body size in men and women.

It has been suggested in previous studies that the difference in endurance performance between males and females is related to gender-specific differences in cardiac function. Other studies have not equated males and females for physical condition, and this may have contributed to the findings. The purpose of this study was to determine the extent to which the difference in VO2max in groups of similarly trained males and females was explained by gender differences in cardiac size, fat-free weight (FFW) and hemoglobin concentration [( Hb]). Measurements of VO2max, FFW, [Hb] and cardiac size (LVM) were made on 19 males and 20 females comparable in age and cardiorespiratory capacity. The difference between men and women in LVM accounted for 68.3% of the gender difference in VO2max, and the combination of LVM and FFW accounted for 98.7% of the gender-related difference in VO2max. It was concluded that the gender difference in LVM accounts for a majority of the difference in VO2max in males and females, with other aspects of body size accounting for nearly all the remaining difference. The gender difference in heart size primarily reflects the smaller overall dimensions of women.

Body Constitution↗
PubMed1989

Subjective equality and just noticeable differences in body-size judgments by obese persons.

Body-size estimates by obese and normal-weight subjects were compared using two different procedures with a TV-video methodology. In the continuous method subjects adjusted an image larger or smaller until they judged a correct TV-image had been achieved. In the second procedure the method of constant stimuli was used wherein values corresponding to the point of subjective equality (PSE) and difference threshold (DL) were determined. No differences between obese and normal-weight subjects were obtained with these procedures. On the continuous task subjects slightly underestimated body size and were more accurate on descending trials where they adjusted the size of the image downwards. With the second procedure, an average PSE of -.62% was obtained, with an average DL = 7.27%. Different PSE values were obtained when subjects were judging whether their image was distorted too wide or too thin. Data from the two procedures are compared and ramifications for the study of body size are discussed.

Body Constitution↗
PubMed2000

The "good enough" body size as judged by people of varying age and weight.

OBJECTIVE: To examine the concept of the "good enough" body size acceptability across a wide range of ages and weight status. RESEARCH METHODS AND PROCEDURES: Subjects were 303 children, 427 adolescents, 261 young adults, and 326 middle-age adults who selected acceptable body sizes from an array of drawings representing their own age and gender. They also selected body sizes representing their own actual and ideal size. RESULTS: A large majority (87%) of subjects considered their own body size socially acceptable. This finding applied to both genders in all age groups and to underweight, normal weight, and overweight subjects. Even among obese subjects, 48% considered their own body size socially acceptable. For the large percentage of subjects who reported a discrepancy between their actual and ideal body sizes, most considered their own body size acceptable. This finding also applied to both genders in all age groups and to underweight, normal weight, and overweight subjects. DISCUSSION: Most male and female subjects across a wide range of ages and status considered their own body size to be within the range of socially acceptable body sizes even though, for many, it did not match their ideal. The implications of expanding body size research to include the conceptual framework of body size acceptability is discussed in terms of contributing to a paradigm of positive psychology.

Adolescent↗
PubMed2000

Continuity and change in the evaluation of ideal and acceptable body sizes across a wide age span.

OBJECTIVE: Continuity and change in the evaluation of ideal and acceptable body sizes across a wide subject age span were examined. METHOD: Ratings of ideal and socially acceptable body sizes were elicited from 303 children, 427 adolescents, 261 young adults, and 326 middle-age adults. Line drawing arrays of babies, children, young adults, middle-age, and older adults were portrayed, ranging in size from very thin to very obese. RESULTS: All subject groups selected, in all arrays, similar ideal body sizes, rated sizes in the midrange of fatness as socially acceptable, and were least accepting of very thin and obese body sizes. Tolerance for body size variations increased with subject age. DISCUSSION: Continuity throughout a wide subject age span was observed in evaluations of body sizes. However, adults were more accepting of body size variations than younger subjects, especially children. Implications of endorsing midrange body sizes for the fashion industry are discussed.

Adolescent↗
PubMed1996

The role of sensory and nonsensory factors in body size estimations of eating disorder subjects.

Body size distortion of anorectic and bulimic subjects was compared to controls via a video-distortion technique. Subjects judged the whole body, chest, hips and stomach regions. A adaptive probit estimation (APE) methodology examined separately the sensory and nonsensory components of body image distortion. Eating disorder subjects overestimated body size more than control subjects. There were no significant differences between eating disorder groups, although there was more variability in eating disorder subjects. Subjects overestimated more on whole body as compared to body regions. There were no differences in sensory sensitivity to detecting size differences between groups. Results indicate that differences in body size distortion between eating disorder and control subjects are due exclusively to affective, nonsensory factors.

Adolescent↗
PubMed2006

Consumer-resource body-size relationships in natural food webs.

It has been suggested that differences in body size between consumer and resource species may have important implications for interaction strengths, population dynamics, and eventually food web structure, function, and evolution. Still, the general distribution of consumer-'resource body-size ratios in real ecosystems, and whether they vary systematically among habitats or broad taxonomic groups, is poorly understood. Using a unique global database on consumer and resource body sizes, we show that the mean body-size ratios of aquatic herbivorous and detritivorous consumers are several orders of magnitude larger than those of carnivorous predators. Carnivorous predator-prey body-size ratios vary across different habitats and predator and prey types (invertebrates, ectotherm, and endotherm vertebrates). Predator-prey body-size ratios are on average significantly higher (1) in freshwater habitats than in marine or terrestrial habitats, (2) for vertebrate than for invertebrate predators, and (3) for invertebrate than for ectotherm vertebrate prey. If recent studies that relate body-size ratios to interaction strengths are general, our results suggest that mean consumer-resource interaction strengths may vary systematically across different habitat categories and consumer types.

Animals↗
PubMed1994

GnRH cell size and number in a teleost fish with two male reproductive morphs: sexual maturation, final sexual status and body size allometry.

Gonadotropin releasing hormone-like immunoreactive (GnRH-ir) cells in both the ganglion of the terminal nerve (TN) and the preoptic area (POA) have been implicated in the development and maintenance of reproductive behavior and physiology in teleost fishes. One marine species, the plainfin midshipman, Porichthys notatus, exhibits two sexually mature male morphs (types I and II) which differ with respect to size at sexual maturation, gonad/body weight index, reproductive tactic and vocal motor traits. Type II males become reproductively active at a smaller body size than either females or type I males. Immunocytochemical techniques and quantitative analyses were used here to determine the size and number of GnRH-ir cells in the TN and POA amongst field collected juveniles, sexually mature females, and type I and II males. Mean GnRH-ir cell size and number in the TN did not vary across the entire range of specimens. However, mean GnRH-ir cell size and number in the POA were 50-100% greater in sexually mature adults compared to juveniles. Analyses of covariance indicated that increases in cell number, but not cell size, could be explained solely on the basis of changes in body size. However, regression analyses showed that body size had a significant influence on increasing cell number only in the juvenile-type I male transition and the juvenile-female transition, not in the juvenile-type II male transition. The latter suggests that type II males, unlike the other adult morphs, have 'escaped' from a body size constraint imposed on increasing GnRH-ir cell number in the POA. There were also significant differences among the adult morphs in the size of GnRH-ir POA cells that could not be explained on the basis of differences in body size but, rather, appear to reflect differences in the temporal onset of sexual maturation. Together, the data suggest that the timing of changes in POA phenotype may provide a proximate mechanism permitting the development of alternative male reproductive morphs.

Animals↗
PubMed2006

Ancestral state reconstruction of body size in the Caniformia (Carnivora, Mammalia): the effects of incorporating data from the fossil record.

A recent molecular phylogeny of the mammalian order Carnivora implied large body size as the ancestral condition for the caniform subclade Arctoidea using the distribution of species mean body sizes among living taxa. "Extant taxa-only" approaches such as these discount character state observations for fossil members of living clades and completely ignore data from extinct lineages. To more rigorously reconstruct body sizes of ancestral forms within the Caniformia, body size and first appearance data were collected for 149 extant and 367 extinct taxa. Body sizes were reconstructed for four ancestral nodes using weighted squared-change parsimony on log-transformed body mass data. Reconstructions based on extant taxa alone favored large body sizes (on the order of 10 to 50 kg) for the last common ancestors of both the Caniformia and Arctoidea. In contrast, reconstructions incorporating fossil data support small body sizes (< 5 kg) for the ancestors of those clades. When the temporal information associated with fossil data was discarded, body size reconstructions became ambiguous, demonstrating that incorporating both character state and temporal information from fossil taxa unambiguously supports a small ancestral body size, thereby falsifying hypotheses derived from extant taxa alone. Body size reconstructions for Caniformia, Arctoidea, and Musteloidea were not sensitive to potential errors introduced by uncertainty in the position of extinct lineages relative to the molecular topology, or to missing body size data for extinct members of an entire major clade (the aquatic Pinnipedia). Incorporating character state observations and temporal information from the fossil record into hypothesis testing has a significant impact on the ability to reconstruct ancestral characters and constrains the range of potential hypotheses of character evolution. Fossil data here provide the evidence to reliably document trends of both increasing and decreasing body size in several caniform clades. More generally, including fossils in such analyses incorporates evidence of directional trends, thereby yielding more reliable ancestral character state reconstructions.

Animals↗
PubMed2006

Geographical variation in relationships between parental body size and offspring phenotype at birth.

BACKGROUND: Size and body proportions at birth are partly determined by maternal body composition, but most studies of mother-baby relationships have only considered the effects of maternal height and weight on offspring birth weight, and few have examined the size of effects. Paternal size and body composition also play a role, primarily through the fetal genome, although few studies have investigated relationships with neonatal phenotype. METHODS: Data from the UK, Finland, India, Sri Lanka, China, DR Congo, Nigeria and Jamaica were used to investigate the effects of maternal measures (derived at 30 weeks' gestation, n=16,418), and also paternal size (n=3,733) on neonatal phenotype, for singleton, live-born, term births. RESULTS: After accounting for variation in maternal size and shape across populations, differences in neonatal phenotype were markedly reduced. Mother-baby relationships were similar across populations, although some were stronger in developing countries. Maternal height was generally the strongest predictor of neonatal length, maternal head circumference of neonatal head and maternal skinfold thickness of neonatal skinfolds. Relationships with maternal arm muscle area were generally weak. Effects of paternal height and body mass index were weaker than the equivalent maternal measurements in most studies. CONCLUSIONS: Differences in maternal body composition account for a large part of the geographical variation in neonatal phenotype. The size of the effects of all maternal measures on neonatal phenotype suggests that nutrition at every stage of the mother's life cycle may influence fetal growth. Further research is needed into father-baby relationships and the genetic mechanisms that influence fetal growth.

Adult↗
PubMed2002

The 'island rule' in birds: medium body size and its ecological explanation.

Do birds show a different pattern of insular evolution from mammals? Mammals follow the 'island rule', with large-bodied species getting smaller on islands and small-bodied species getting bigger. By contrast, the traditional view on birds is that they follow no general island rule for body size, but that there is an insular trend for large bills. Insular shifts in feeding ecology are, therefore, widely assumed to be the primary cause of divergence in island birds. We use a comparative approach to test these ideas. Contrary to the traditional view, we find no evidence for increased bill size in insular populations. Instead, changes in both bill size and body size obey the 'island rule'. The differences between our results and the traditional view arise because previous analyses were based largely on passerines. We also investigate some ecological factors that are thought to influence island evolution. As predicted by the traditional view, shifts in bill size are associated with feeding ecology. By contrast, shifts in body size are associated with the potential for intraspecific competition and thermal ecology. All these results remain qualitatively unchanged when we use different methods to score the ecological factors and restrict our analyses to taxa showing pronounced morphological divergence. Because of strong covariation between ecological factors, however, we cannot estimate the relative importance of each ecological factor. Overall, our results show that the island rule is valid for both body size and bill length in birds and that, in addition to feeding ecology, insular shifts in the level of intraspecific competition and the abiotic environment also have a role.

Analysis of Variance↗