Effects of diet macronutrient composition on body composition and fat distribution during weight maintenance and weight loss

Objective: Neurotransmitter systems participate in the regulation of food intake, and their activities are expected to influence eating behavior. Design and Methods: We investigated possible associations between body mass index (BMI) and central noradrenaline, serotonin, and dopamine activities, as reflected by the cerebrospinal fluid levels of their main metabolites methoxyhydroxyphenylglycol (MHPG), 5‐hydroxyindoleacetic acid (5‐HIAA), and homovanillic acid (HVA), respectively. We studied 192 subjects (111 males, 81 females) admitted to neurologic clinic for diagnostic investigations that included CSF analysis, and were found not to suffer from any major neurological disease. Subjects were categorized in three groups, namely in lower, in the two middle, and in upper BMI quartiles, the limits calculated separately for males and females. Results: No differences were found in MHPG levels between groups, while subjects in the upper BMI quartile showed significantly elevated levels of 5‐HIAA and HVA compared to the levels of subjects in lower and middle quartiles. Conclusions: The results provide evidence that in overweight subjects there are enhanced demands in serotoninergic and dopaminergic signaling for their reward system that may lead to increased motivation for food consumption. The implication of reward centers in eating behavior supports the hypothesis of common mechanisms in obesity and drug addiction.     

Impact of variation in the FTO gene on whole body fat distribution, ectopic fat, and weight loss

Polymorphisms in the fat mass- and obesity-associated (FTO) gene have been identified to be associated with obesity and diabetes in large genome-wide association studies. We hypothesized that variation in the FTO gene has an impact on whole body fat distribution and insulin sensitivity, and influences weight change during lifestyle intervention. To test this hypothesis, we genotyped 1,466 German subjects, with increased risk for type 2 diabetes, for single-nucleotide polymorphism rs8050136 in the FTO gene and estimated glucose tolerance and insulin sensitivity from an oral glucose tolerance test (OGTT). Distribution of fat depots was quantified using whole body magnetic resonance (MR) imaging and spectroscopy in 298 subjects. Two-hundred and four subjects participated in a lifestyle intervention program and were examined after a follow-up of 9 months. In the cross-sectional analysis, the A allele of rs8050136 in FTO was associated with a higher BMI, body fat, and lean body mass (all P < 0.001). There was a significant effect of variation in the FTO gene on subcutaneous fat (P < or = 0.05) and a trend for liver fat content, nonvisceral adipose tissue, and visceral fat (all P < or = 0.1). However, the single-nucleotide polymorphism was not associated with insulin sensitivity or secretion independent of BMI (all P > 0.05). During lifestyle intervention, there was also no influence of the FTO polymorphism on changes in body weight or fat distribution. In conclusion, despite an association with BMI and whole body fat distribution, variation in the FTO locus has no effect on the success of a lifestyle intervention program.     

Anthropometric measures, body composition, body fat distribution, and knee osteoarthritis in women

Objective: Increased BMI is a well‐recognized risk factor for radiographic knee osteoarthritis (rKOA); however, the contributions of the components of body composition, body fat distribution, and height to this association are not clear. Research Methods and Procedures: We examined 779 women ≥45 years of age from the Johnston County Osteoarthritis Project. Body composition was assessed using DXA, and rKOA was defined as Kellgren‐Lawrence grade ≥2. Logistic regression models examined the association between rKOA and the fourth compared with the first quartiles of anthropometric, body composition, and fat distribution measures adjusting for age, ethnicity, and prior knee injury. Results: The adjusted odds ratios and 95% confidence interval of BMI and weight were 5.27 (3.05, 9.13) and 5.28 (3.05, 9.16), respectively. In separate models, higher odds of rKOA were also found for fat mass [4.54 (2.68, 7.69)], percent fat mass [3.84 (2.26, 6.54)], lean mass [3.94 (2.22, 6.97)], and waist circumference [4.15 (2.45, 7.02)]. Waist‐to‐hip ratio was not associated with rKOA [1.45 (0.86, 2.43)], and percent lean mass was associated with lower odds [0.20 (0.11, 0.35)]. Taller women had higher odds of rKOA after adjustment for BMI [1.77 (1.05, 3.00)]. Discussion: This study confirms that BMI and weight are strongly associated with rKOA in women and suggests that precise measurements of body composition and measures of fat distribution may offer no advantage over the more simple measures of BMI or weight in assessment of risk of rKOA.     

Monogenic disorders of obesity and body fat distribution.

Recently, great progress has been made towards understanding the molecular basis of body fat regulation. Identification of mutations in several genes in spontaneous monogenic animal models of obesity and development of transgenic models have indicated the physiological roles of many genes in the regulation of body fat distribution. In humans, mutations in leptin, leptin receptor, prohormone convertase 1 (PC1), pro-opiomelanocortin (POMC), melanocortin 4-receptor (MC4-R), and peroxisome proliferator-activated receptor (PPAR) gamma2 genes have been described in patients with severe obesity. Most of these obesity disorders exhibit a distinct phenotype with varying degrees of hypothalamic and pituitary dysfunction and a recessive inheritance, whereas MC4-R mutation has a nonsyndromic phenotype with dominant inheritance. These mutations suggest the critical role of central signaling systems composed of leptin/leptin receptor and alpha-melanocyte stimulating hormone/MC4-R in human energy homeostasis. Although the genetic basis of monogenic disorders of body fat distribution, such as congenital generalized lipodystrophy and familial partial lipodystrophy, Dunnigan variety, is still unknown, the genes for these have recently been localized to chromosomes 9q34 and 1q21-22, respectively. The advances in our knowledge of the phenotypic manifestations and underlying molecular mechanisms of genetic body fat disorders may lead to better treatment and prevention of obesity and other disorders of adipose tissue in the future.     

Small birth weight and later body composition and fat distribution in adolescents: the Avena study

Objective: To assess the association between birth weight and body composition and fat distribution in adolescents, and to test the possible sex‐specific effect in these relationships. Methods and Procedures: A total of 1,223 adolescents 13–18.5 years old (553 male adolescents and 670 female adolescents) born at >35 weeks, were selected from a cross‐sectional multicenter study conducted in five Spanish cities in 2000–2002. BMI was calculated from weight and height. Triceps and subscapular skinfold thickness (ST) were measured on the left side, and fat mass (FM) and fat‐free mass (FFM) were estimated according to the equations of Slaughter et al. Subscapular skinfold adjusted by tricipital (ST) and waist circumference were used as markers of central adiposity. Results: Birth weight Z‐score was positively associated with FFM in female adolescents (P < 0.001), but not in male adolescents, after controlling for age, pubertal stage, gestational age, socioeconomic status, physical activity, and current height (P < 0.001 for interaction between adjusted birth weight Z‐score and sex). Adjusted birth weight Z‐score was inversely associated with central adiposity in male and female adolescents as measured by ST (P = 0.026). Discussion: These results provide further evidence that gender has an important influence on the programming effect of birth weight on later FFM in adolescents because the effect was only observed in female adolescents. Our results suggest that small size for gestational age at birth could program more central subcutaneous fat deposition in adolescents of both sexes, but further research is needed on this issue.     

Comparison of body fat composition and serum adiponectin levels in diabetic obesity and non-diabetic obesity

Objective: Clinical aspects of diabetes and obesity are somewhat different, even at similar levels of insulin resistance. The purpose of this study was to determine differences in body fat distribution and serum adiponectin concentrations in diabetic and non‐diabetic obese participants. We were also interested in identifying the characteristics of insulin resistance in these two groups, particularly from the standpoint of adiponectin. Research Methods and Procedures: Adiponectin concentrations of 112 type 2 diabetic obese participants and 124 non‐diabetic obese participants were determined. Abdominal adipose tissue areas and midthigh skeletal muscle areas were measured by computed tomography. A homeostasis model assessment of the insulin resistance score was calculated to assess insulin sensitivity. The relationships among serum adiponectin, body fat distribution, and clinical characteristics were also analyzed. Results: Both abdominal subcutaneous and visceral fat areas were higher in the non‐diabetic obese group, whereas midthigh low‐density muscle area was higher in the diabetic obese group. The homeostasis model assessment of the insulin resistance score was similar between groups, whereas serum adiponectin was lower in the diabetic obese group. Abdominal visceral fat (β = ?0.381, p = 0.012) was a more important predictor of adiponectin concentration than low‐density muscle (β = ?0.218, p = 0.026) in cases of non‐diabetic obesity, whereas low‐density muscle (β = ?0.413, p = 0.013) was a better predictor of adiponectin level than abdominal visceral fat (β = ? 0.228, p = 0.044) in diabetic obese patients. Discussion: Therefore, factors involved in pathophysiology, including different serum adiponectin levels and body fat distributions, are believed to be responsible for differences in clinical characteristics, even at similar levels of insulin resistance in both diseases.     

The effects of caloric restriction- and exercise-induced weight loss on left ventricular diastolic function

Little is known about the effects of weight loss on diastolic function. Furthermore, it is not known whether both caloric restriction (CR)- and exercise (Ex)-induced weight loss have salutary effects on diastolic function. Therefore, we assessed the effects of yearlong CR (n = 12) and Ex (n = 13) interventions, which induced approximately 12% weight loss, on diastolic function in healthy, nonobese (body mass index = 23.5-29.9 kg/m2) men and women aged 50 to 60 yr. Recordings of Doppler transmitral flow and Doppler tissue imaging were acquired and analyzed by conventional approaches and a validated parameterized diastolic filling (PDF) formalism. Isovolumic relaxation time decreased after weight loss in both groups (P < 0.05). Septal peak early mitral annular velocity (E') increased (P < 0.01) and peak E-wave velocity/E' decreased (P < 0.05) after weight loss in the CR group. Based on the PDF-derived indexes, CR resulted in a decrease in global ventricular stiffness (k) and increases in longitudinal (septal annulus motion) stored elastic strain (chi'o), peak force (k'chi'o), and peak stored strain energy (1/2k'chi'o2). In the Ex group, k was unchanged, although septal chi'o and 1/2k'chi'o2 increased significantly and k'chi'o (P = 0.13) tended to increase. We conclude that weight loss, whether induced by CR or Ex, has salutary effects on diastolic function.     

Body fat, abdominal fat, and body fat distribution is related to left atrial diameter in young children

In adults, the size of the left atria (LA) has important prognostic information. In obese adults, adolescents and children enlargement of LA have been observed. This has not been investigated on a population-based level in young children. We therefore assessed if total body fat mass (TBF), abdominal fat, and body fat distribution were related to LA diameter. Cross-sectional study of 244 children (boys = 137 and girls n = 107) aged 8-11 years, recruited from an urban population-based cohort. Dual-energy X-ray absorptiometry (DXA) measured total lean body mass, TBF, and abdominal fat mass (AFM). Body fat was also calculated as a percentage of body mass (BF%). Body fat distribution (AFM/TBF) was calculated. Echocardiography was performed with two-dimensional guided M-mode. LA diameter was measured and left ventricular mass (LVM) was calculated. Systolic blood pressure and diastolic blood pressure were measured and maturity assessed according to Tanner. There were significant (P < 0.05) univariate correlations for all children between TBF (r = 0.40), BF% (r = 0.32), AFM (r = 0.41), and AFM/TBF (r = 0.41) vs. LA diameter. Multiple regression analyses with the inclusion of possible confounders such as lean body mass, blood pressure, gender, age, and Tanner stage revealed that TBF, AFM, and AFM/TBF were all independently related to LA diameter. Differences in the different body fat measurements explained 6-9% of the variance in LA size. These results demonstrated that both total body fat, AFM, and body fat distribution are already at a young age negatively and independently associated to LA diameter.     

Erythrocyte hyperaggregation in obesity: determining factors and weight loss influence

Objective: To compare erythrocyte aggregation (EA) in patients with severe obesity without other cardiovascular risk factors with a control group, using the Myrenne and the Sefam aggregometers, and to evaluate the effect of weight loss on this parameter. Research Methods and Procedures: This was a longitudinal, clinical intervention study of a very low‐calorie diet for 4 weeks followed by a low‐calorie diet for 2 months. In 67 severely obese patients, an anthropometric and analytical evaluation [plasmatic lipids, fibrinogen (Fbg), and EA] was performed at baseline and 3 months after diet. The same determinations were performed in 67 normal‐weight volunteers. EA was measured with the Myrenne MA₁, which determines EA at stasis (EA₀) and at a low shear of 3 seconds^?1 (EA₁), and the Sefam aggregometer, which determines aggregation index at 10 seconds^?1 (IA₁₀), aggregation time (Ta), and disaggregation threshold (γD). Insulin resistance (IR) was calculated by homeostasis model assessment. Results: Obese patients showed higher Fbg levels, EA₀, EA₁, IA₁₀, and γD values, and lower Ta values. Differences between obese patients and control group for EA₀, EA₁, Ta, IA₁₀, and γD disappeared after adjusting for BMI or for homeostasis model assessment but were maintained after adjusting for Fbg or low‐density lipoprotein‐cholesterol. Obese patients with IR showed higher EA₀ and EA₁ values. After weight loss, EA₁ showed a significant improvement. Discussion: Obese patients show increased EA. Erythrocyte hyperaggregation does not seem to be related to a high Fbg level or to an abnormal lipid profile but to IR. Hyperagreggation improves after weight loss.     

Bivariate whole-genome linkage scan for bone geometry and total body fat mass

To quantify the genetic correlations between total body fat mass （TBFM） and femoral neck geometric parameters （FNGPs） and, if pos- sible, to detect the specific genomic regions shared by them, bivariate genetic analysis and bivariate whole-genome linkage scan were carried out in a large Caucasian population. All the phenotypes studied were significantly controlled by genetic factors （P 〈 0.001） with the heritabilities ranging from 0.45 to 0.68. Significantly genetic correlations were found between TBFM and CSA （cross-section area）, W （sub-periosteal diameter）, Z （section modulus） and CT （cortical thickness） except between TBFM and BR （buckling ratio）. The peak bivariate LOD scores were 3.23 （20q12）, 2.47 （20p11）, 3.19 （6q27）, 1.68 （20p12）, and 2.47 （7q11） for the five pairs of TBFM and BR, CSA, CT, W, and Z in the entire sample, respectively. Gender-specific bivariate linkage evidences were also found for the five pairs. 6p25 had complete pleiotropic effects on the variations of TBFM ＆ Z in the female sub-population, and 6q27 and 17q11 had coincident link- ages for TBFM ＆ CSA and TBFM ＆ Z in the entire population. We identified moderate genetic correlations and several shared genomic regions between TBFM and FNGPs in a large Caucasian population.     

Contribution of breast volume and weight to body fat distribution in females

Breast volume and body composition were measured in 45 adult females to determine the contribution of breast weight and breast volume to total body fat. Plaster casts were filled with sand of known density to obtain breast volume. Breast weight was computed as breast volume times its density. The correlation between total breast volume and percent body fat was r = .40. Breast weight (X = 484 grams) accounted for 3.5 percent of the total weight of body fat, and at most, 12 percent of the estimated quantities of sex-specific fat. A theoretical model is proposed for the distribution of body fat in the female which subdivides total body fat into three components: reserve storage fat, essential fat, and expendable storage fat.     

The influence of body mass, climate, and distribution on the energetics of South Pacific pigeons

Rate of metabolism and temperature regulation were studied in 16 species of South Pacific pigeons, which constitute 13 fruit-eaters, 1 seed-eater, 1 fruit/nut-eater, and 1 fruit/leaf-eater; 14 tropical and two temperate species; and ten mainland and six intermediate- or small-island species. The data presented here and those from 11 additional columbids indicate in an analysis of covariance that log(10) basal rate of metabolism is correlated with log(10) body mass (P< or =0.0001), distribution (P=0.0023), and climate (P=0.0016). These factors account for 94.3% of the variation in log(10) basal rate of metabolism. In this analysis the lowest basal rates, corrected for body mass, are found in tropical pigeons living on small oceanic islands, whereas the highest basal rates are found in temperate species living on continents. The reduction of basal rate in large columbids facilitates their long-term persistence on small islands characterized by a limited resource base and unstable weather. Some small-island specialists have a smaller mass than their continental relatives, which further reduces resource requirements. The question whether a reduction in basal rate occurs in small columbids on small islands is unresolved. Log(10) minimal thermal conductance is apparently correlated only with log(10) body mass (P< or =0.0001); r(2)=89.4%. The mean nocturnal body temperature of columbids is 39.7 degrees C.