Effects of 3 hours a week of physical activity on body fat and cardio-respiratory parameters in obese boys

The prevalence of overweight or fat children and adolescents has markedly increased in Hungary during the past three decades. Among the possible factors insufficient physical activity and a relative or absolute excess of calorie intake associated to it can be regarded as the most important ones. The aim of the study was to analyse the effects of a 20-week aerobic exercise on body composition and on the exercise tested cardio-respiratory functions in 10-year-old obese boys. Obesity was defined by a BMI greater than the cut-off value reported by Cole and co-workers (5) and a relative body fat content above 30% (13). Of the study group 21 volunteer children completed the program; the contrast group contained 28 obese boys. Mean calendar age was 10.03 +/- 0.26 in the study group (S) and 9.88 +/- 0.29 in the control group (C). The members of group S had two curricular physical education (PE) classes a week and three extracurricular aerobic physical activity sessions of 60 min net time in the afternoon, on Mondays (swimming and water games), Wednesdays (folk dance) and Fridays (soccer). Group C had only 2 PE classes a week. Anthropometric and spiroergometric data were collected in the middle of January and June of 2004. Relative body fat content and BMI did not increase during the observation period in contrast to the significant increase of both in the control group. Peak minute ventilation, aerobic power, oxygen pulse, and running distance (performed on a treadmill) increased in group S, and did not change in group C. The program was considered successful despite that the changes in the observed physiological and physical indicators appeared to be slight. However, the 5-month elevated level of physical activity brought about such development in the physical status of the obese subjects that might be an appropriate basis for regular training. Fortunately, the cardio-respiratory functions of the investigated boys were not affected yet by obesity, consequently the really dramatic change in their further lifestyle exclusively depends on their decision.     

Exogenous human growth hormone reduces body fat in obese women

The effects of biosynthetic methionyl human growth hormone (met-hGH) on body composition and endogenous secretion of insulin-like growth factor I (IGF-I) were studied in obese women ranging between 138 and 226% of ideal body weight. Following double-blind procedures, 12 subjects were assigned at random to either treatment with met-hGH (n = 6, 0.08 mg/kg desirable body weight) or placebo (n = 6, bacteriostatic water diluent). Treatments were delivered intramuscularly three times per week for a period of 27-28 days. Subjects were instructed to follow a weight-maintaining diet and their pre- and posttreatment kilocaloric intake was monitored for verification. The baseline peak serum GH response to L-dopa/arginine stimulation for the study population as a whole, was in the hyposecretory range (9.6 +/- 1.9 ng/ml), accompanied by a low level of circulating IGF-I (0.56 +/- 0.09 U/ml). Hydrodensitometry revealed that the met-hGH-treated subjects had a significant reduction in body fat, while an observed mean increase in fat-free mass (FFM) approached significance. The percent change in body fat was unrelated to pretreatment levels of body fat, total body weight, or initial endogenous GH status. Changes in circulating IGF-I were similar to those for FFM, with increases approaching significance. There were no significant changes in body composition or IGF-I in the placebo-treated subjects. No significant differences were observed in the self-reported dietary intake of kilocalories during the experimental period between the two groups. We conclude that exogenous GH reduces body fat in obese women in the apparent absence of significant kilocaloric restriction. The effect appears to be unrelated to endogenous GH secretion or body composition.     

Activity-related changes in protein phosphorylation in an identifiedAplysia neuron

The relationship between long-term electrical activity and protein phosphorylation was investigated in single, identifiable neurons in the abdominal ganglion of Aplysia californica by the intracellular injection of radiolabeled ATP followed by sodium dodecyl sulfate (SDS) gel electrophoresis. Natural and pharmacological treatments that alter the impulse activity of neurons L6 and R15 for prolonged periods did not appear to affect the phosphorylation of most of the 15 major phosphoproteins examined in these cells. Long-term excitation of L6 induced by the phosphodiesterase inhibitor IBMX correlated with phosphorylation of a 29,000-dalton protein. Long-term inhibition of L6 induced by afterdischarge of peptidergic bag-cell neurons appeared to cause dephosphorylation of a 29,000-dalton protein. Burst augmentation of R15 induced by bag-cell afterdischarge did not cause detectable changes in the phosphorylation of the major proteins we examined. These data are consistent with other studies of neural and nonneural tissues which have found a correlation between activity and the level of phosphorylation of a 29,000-dalton protein.     

Preferential loss of body fat during starvation in dietary obese rats.

This study was undertaken to examine whether diet-induced obesity alters the amount and/or composition of weight lost during starvation. The amount and composition of weight lost during a 4-day period of starvation was determined before and at 17, 30 and 42 weeks after rats (350 g of body weight) were given a high fat diet (HFD). To control for effects of aging, a second group of rats, fed standard laboratory chow, was also subjected to similar periods of starvation. Although total weight loss during starvation was never greater for HFD rats than for chow-fed rats, the former group showed a clear patter of increasing loss of body fat and total energy and conservation of fat-free tissues with periods of starvation later in life. In addition, chow-fed rats showed substantial energy conservation during each period of starvation (i.e. they lost less energy each day than their pre-starvation energy requirements). In contrast, HFD rats demonstrated substantial energy conservation only at 17 weeks and not at 30 or 42 weeks; during the last period of starvation, their average daily loss of carcass energy exceeded their pre-starvation energy requirements. This suggests the increased fat mass of these rats may have led to increased fuel availability and to an increased metabolic rate during starvation. If these results are applicable to humans, the more obese subjects are likely to show greater total loss of energy than lean subjects, but show a lesser loss of lean body mass, at least initially. If protein requirements are reflected by the ability to mobilize protein during food restriction, protein requirements would be substantially lower in the dietary obese rats than in controls. In summary, diet-induced obesity leads to preferential loss of body fat and conservation of lean mass during starvation.     

Zinc supplementation aggravates body fat accumulation in genetically obese mice and dietary-obese mice

A perturbation of zinc metabolism has been noted in numerous laboratory animals with diabetes and obesity. The effects of zinc supplementation on body fat deposition in two types of experimental obese mice: genetically obese (ob/ob) mice and high-fat diet-induced ICR obese (HF) mice were investigated in this study. Their lean controls were +/? mice, and ICR on basal diet, respectively. The mice in the zinc-supplemented groups were administered 200 mg/kg zinc in their diets for 6 wk. Both the ob/ob mice and the HF mice, that were fed a diet containing a marginal zinc dosage (4–6 mg/kg), had lower zinc levels in their serum and carcass, and higher body fat content than their respective lean controls (p<0.01). After zinc supplementation, ob/ob mice and the HF mice significnatly (p<0.05) increased their body fat by 49.4% and 18.9%, respectively. This study revealed that body fat deposition can be aggravated by zinc supplementation in both types of obese mice. Zinc may be associated with the energy homeostasis of obesity, via its interaction with dietary fat consumption.     

Age-dependent changes in body size of Greek boys from 1982 to 2002

Objective: The prevalence of childhood obesity has been rising during the past decades in many parts of the world, including Greece. The dispersion of these trends across age, however, is less clear. The aim of this study was to examine the relationship between age and 20‐year changes in anthropometric characteristics of Greek boys. Research Methods and Procedures: A total of 204 and 106 boys 9 years old, 163 and 274 boys 12 years old, and 161 and 240 boys 15 years old were randomly recruited in 1982 and 2002, respectively, throughout the county of Iraklio, Crete, Greece. Height, weight, and BMI were measured. Results: Contemporary 9 and 12 year olds were taller than their peers in 1982 (+2.9% and +1.2%, respectively; p < 0.005), but this was not the case for 15 year olds (?0.8%; p = 0.083). Body weight and BMI were higher now than in the 1980s, and this held true for all age groups (p < 0.001). Increases in weight also showed a decline with advancing age (+17.4%, +13.9%, and +4.0% for 9, 12, and 15 year olds, respectively), whereas BMI changes were similar for those 9 and 12 years of age (～10.5%), but were almost 2‐fold higher than in 15 year olds (+5.5%). Discussion: Contemporary boys are taller, heavier, and have higher BMI values than their peers in 1982, but the magnitude of these increases gradually declines with advancing age. Rates of increase in BMI, however, seem to have greatly accelerated compared with previous decades.     

Developmental changes in fat body and midgut chromosomes of Drosophila auraria

Changes in puffing activity of fat body (FB) and midgut (MG) chromosomes of Drosophila auraria during late larval and white prepupal development as well as after in vitro culture with or without ecdysterone were studied and compared with those of the salivary gland (SG). The Balbiani Rings characteristic of the SG chromosomes of D. auraria, are not formed in FB and MG. Most of the inverted tandem chromosomal duplications that have been found to be common to all three tissues showed differentiation of puffing activity of the bands considered to be homologous. The major early ecdysone puffs 73A and 73B (considered to be homologues of D. melanogaster puffs 74EF and 75B, respectively), together with other early ecdysone puffs were present in all three tissues. Clear intermoult and postintermoult puffs were not evident in FB and MG chromosomes. However, a small set of late ecdysone puffs could be scored in FB, while no late ecdysone puffs were abserved in MG. Other tissue-specific puffs were identified, but a very small number of them were limited to MG.by W. Beermann     

Direct innervation of white fat and adrenal medullary catecholamines mediate photoperiodic changes in body fat

Seasonal adjustments in Siberian hamster adiposity are triggered by day length changes [i.e., short "winter-like" days (SDs) elicit body fat decreases vs. long "summer-like" days (LDs)]. These and other white adipose tissue (WAT) mass decreases traditionally have been ascribed to lipolysis triggered by sympathetically mediated, adrenal medullary released epinephrine; however, recent evidence suggests that direct sympathetic innervation of WAT also is important. Therefore, the contributions of WAT sympathetic innervation and adrenal medullary catecholamines to SD-induced decreases in adiposity were tested. Siberian hamsters were surgically bilaterally adrenal demedullated (ADMEDx) or sham ADMEDx, and all had one inguinal WAT (IWAT) pad sympathectomized via locally injected guanethidine, with the contralateral pad serving as a within-animal innervated control. One-half of the hamsters remained in LDs; the remainder was transferred to SDs. Guanethidine and ADMEDx abolished IWAT norepinephrine and adrenal epinephrine contents, respectively. Although sympathetic denervation or ADMEDx alone did not block SD-induced decreases in IWAT mass, their combination did. These results suggest that both adrenal catecholamines and the sympathetic innervation of WAT interact to decrease SD-induced decreased adiposity.     

Increasing dietary fat elicits similar changes in fat oxidation and markers of muscle oxidative capacity in lean and obese humans

In lean humans, increasing dietary fat intake causes an increase in whole-body fat oxidation and changes in genes that regulate fat oxidation in skeletal muscle, but whether this occurs in obese humans is not known. We compared changes in whole-body fat oxidation and markers of muscle oxidative capacity differ in lean (LN) and obese (OB) adults exposed to a 2-day high-fat (HF) diet. Ten LN (BMI = 22.5±2.5 kg/m², age = 30±8 yrs) and nine OB (BMI = 35.9±4.93 kg/m², 38±5 yrs, Mean±SD) were studied in a room calorimeter for 24hr while consuming isocaloric low-fat (LF, 20% of energy) and HF (50% of energy) diets. A muscle biopsy was obtained the next morning following an overnight fast. 24h respiratory quotient (RQ) did not significantly differ between groups (LN: 0.91±0.01; OB: 0.92±0.01) during LF, and similarly decreased during HF in LN (0.86±0.01) and OB (0.85±0.01). The expression of pyruvate dehydrogenase kinase 4 (PDK4) and the fatty acid transporter CD36 increased in both LN and OB during HF. No other changes in mRNA or protein were observed. However, in both LN and OB, the amounts of acetylated peroxisome proliferator-activated receptor γ coactivator-1-α (PGC1-α) significantly decreased and phosphorylated 5-AMP-activated protein kinase (AMPK) significantly increased. In response to an isoenergetic increase in dietary fat, whole-body fat oxidation similarly increases in LN and OB, in association with a shift towards oxidative metabolism in skeletal muscle, suggesting that the ability to adapt to an acute increase in dietary fat is not impaired in obesity.     

Substantial changes in epicardial fat thickness after weight loss in severely obese subjects

We sought to evaluate the effect of weight loss on echocardiographic epicardial fat thickness, as index of visceral adiposity, and whether epicardial fat change after the weight loss can be proportionally different from overall body weight changes and related to cardiac parameters changes in severely obese subjects. This was an interventional study in 20 severely obese subjects (12 women, 8 men, BMI 45+/-5 kg/m(2), 35+/-10 years) who underwent 6-month very low calorie diet weight loss program. Baseline and after 6-month weight loss anthropometrics, echocardiographic epicardial fat thickness, left ventricular mass (LVM), and diastolic function parameters were assessed. Subjects lost 20% of original body weight, BMI reduced by 19% of original BMI, waist circumference decreased by 23% of initial waist circumference. Epicardial fat thickness decreased from 12.3+/-1.8 to 8.3+/-1 mm P<0.001 after the 6-month very low calorie diet, as -32% of baseline epicardial fat thickness. LVM and diastolic function changes were better correlated with epicardial fat changes. We showed that significant weight loss can be associated with significant reduction in the epicardial fat thickness, marker of visceral adiposity in severely obese subjects. Epicardial fat decrease, therefore visceral fat decrease, can be proportionally higher than overall adiposity decrease. Epicardial fat changes are significantly associated with obesity-related cardiac morphological and functional changes during weight loss. Measurement of echocardiographic epicardial fat thickness may provide an additional tool in understanding the metabolic risk associated with variation in fat distribution.     

Morpho-functional changes of fat body in bacteria fed Drosophila melanogaster strains

We have examined the addition of Escherichia coli to the diet at day 0 of adult life of females from two Oregon R Drosophila melanogaster strains, selected for different longevities: a short-life with an average adult life span of 10 days and a long-life standard R strain with an average adult life span of 50 days. The addition of bacteria to the diet significantly prolonged the fly longevity in both strains and affected the structure and histochemical reactivity of the fat body. The increased survival was characterized by great amount of glycogen accumulated in fat body cells from both strains. In aged control animals, fed with standard diet, lipid droplets were seen to be stored in fat body of short-lived, but not long-lived, flies. On the whole, our data indicate that exogenous bacteria are able to extend the survival of Drosophila females, and suggest that such a beneficial effect can be mediated, at least in part, by the fat body cells that likely play a role in modulating the accumulation and mobilization of reserve stores to ensure lifelong energy homeostasis.     

Effect of 6-month athletic training on motor abilities in seven-year-old schoolgirls

The effects of six-month athletic training on improving motor abilities in 7-year-old schoolgirls were assessed. Analysis of the results of 12 motor tests showed significant improvement in the study group (n = 38) in comparison with control group (n = 140) subjected to conventional physical education classes only. The improvement referred to the variables of aerobic endurance (3-min run), flexibility (forward bow), explosive strength (ball throwing and 20-m run), keeping balance (bench standing), static strength (bent arm hang), and repetitive strength (sit-ups). These are probably adaptive changes brought up by discriminant functions. The varimax factor and discriminative function correlations indicated that all four factors of changes contributed significantly to the explanation of discriminative function. An almost equally high correlation of varimax factors and discriminative function was obtained on the basis of differences in the third factor responsible for changes in the frequency of movements and in the explosive strength of the jump type; in the second factor responsible for changes in coordination with changes in the repetitive strength of the body; and in the fourth factor responsible for changes in the explosive strength of the throw and sprint types with changes and endurance.     

Comparison of body adiposity index (BAI) and bmi with estimations of % body fat in clinically severe obese women

Objective:

Body adiposity index (BAI), a new surrogate measure of body fat (hip circumference/(height^1.5 – 18)), has been proposed as an alternative to body mass index (BMI). We compared BAI with BMI, and each of them with laboratory measures of body fat‐derived from bioimpedance analysis (BIA), air displacement plethysmography (ADP), and dual‐energy X‐ray absorptiometry (DXA) in clinically severe obese (CSO) participants.

Design and Methods:

Nineteen prebariatric surgery CSO, nondiabetic women were recruited (age = 32.6 ± 7.7 SD; BMI = 46.5 ± 9.0 kg/m²). Anthropometrics and body fat percentage (% fat) were determined from BIA, ADP, and DXA. Scatter plots with lines of equality and Bland–Altman plots were used to compare BAI and BMI with % fat derived from BIA, ADP, and DXA. BAI and BMI correlated highly with each other (r = 0.90, P < 0.001).

Results:

Both BAI and BMI correlated significantly with % fat from BIA and ADP. BAI, however, did not correlate significantly with % fat from DXA (r = 0.42, P = 0.08) whereas BMI did (r = 0.65, P = 0.003). BMI was also the single best predictor of % fat from both BIA (r² = 0.80, P < 0.001) and ADP (r² = 0.65, P < 0.001). The regression analysis showed that the standard error of the estimate (SEE), or residual error around the regression lines, was greater for BAI comparisons than for BMI comparisons with BIA, ADP, and DXA. Consistent with this, the Bland and Altman plots indicated wider 95% confidence intervals for BAI difference comparisons than for BMI difference comparisons for their respective means for BIA, ADP, and DXA.

Conclusions:

Thus, BAI does not appear to be an appropriate proxy for BMI in CSO women.     

A cross‐sectional study of osteocalcin and body fat measures among obese adolescents

Osteocalcin (OCN), a marker of osteoblast activity, has been implicated in the regulation of energy metabolism by the skeleton and thus may affect body fat measures.

Objective:

To examine the relationships of OCN to body fat measures and whether they vary according to markers of energy and vitamin D metabolism.

Design and Methods:

Data were obtained from 58 obese adolescents aged 13‐17.9 years (38 females, 8 black or African‐American). Total fat mass (FM) [dual X‐ray absorptiometry (DXA)] and visceral adipose tissue (VAT) [computerized axial tomography (CT)] were calculated. Blood tests included leptin, OCN, 25‐hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH), thyroid function tests, and triglycerides. Markers of glucose metabolism were obtained from fasting and OGTT samples.

Results and Conclusions:

Adolescents with 25(OH)D <20 ng mL^?1 were considered deficient (n = 17/58); none had high PTH (PTH ≥ 65 pg mL^?1). OCN was associated with lower VAT (?84.27 ± 33.89 mm²) and BMI (?0.10 ± 0.05 kg m^?2), not FM (P = 0.597) in a core model including age, sex, race, geographic latitude, summer, height z‐score, and tanner stage. Adding 25(OH)D deficiency and PTH attenuated the inverse association of OCN to VAT. There was a significant interaction of OCN and 25(OH)D deficiency on FM (0.37 ± 0.18 kg, P = 0.041) and BMI (0.28 ± 0.10 kg m^?2, P = 0.007) in this adjusted model, which was further explained by leptin. Adding A1C to the core model modified the relationship of OCN to VAT (?93.08 ± 35.05 mm², P = 0.011), which was further explained by HOMA‐IR. In summary, these findings provide initial evidence for a relationship between OCN and body fat measures that is dependent on energy metabolism and vitamin D status among obese adolescents.

     

Dynamic changes of orexin A and leptin in obese children during body weight reduction

In this study, we describe changes of plasma levels of the hypothalamic neuropeptide orexin A in obese children during the reduction of body weight and its relationship to other biochemical and anthropometrical parameters. We measured orexin A fasting plasma levels by the RIA method in 58 obese children--33 girls and 25 boys; mean age 13.1+/-0.38 years (range 7-18.5) before and after 5 weeks of weight-reduction therapy. Leptin, IGF-1, and IGFBP-3 levels were measured in all the subjects and were compared to orexin A levels and anthropometrical data. Average weight in subjects before weight-reduction was 74.2+/-2.79 kg and after weight-loss 67.4+/-2.60 kg (p<0.0001). Orexin A levels before the therapy were 33.3+/-1.97 pg/ml and after the therapy 51.7+/-3.07 pg/ml (p<0.0001). Levels of orexin A were not significantly different between girls and boys (p=0.7842). We found negative correlation between orexin A and age (r = -0.5395; p<0.0001), body height (r = -0.4751; p=0.0002), body weight (r = -0.4030; p=0.0017) and BMI (r = -0.2607; p=0.0481). No correlation was found between orexin A and IGF-1, IGFBP-3 or leptin. Orexin A plasma levels increased during body weight loss, whereas the reverse was true for leptin levels. These findings support the hypothesis that orexin A may be involved in regulation of nutritional status in children.