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Biomedical subjects

S B Roberts

Publications and source records attributed to S B Roberts.

At least 37 records · Page 2Linked to original sources
PubMed2001

Dietary energy density and weight regulation.

Dietary energy density (ED) has been suggested as an important determinant of energy intake and, therefore, energy regulation. This review summarizes published studies on the effects of dietary ED on hunger, satiety, energy intake, and body weight in healthy individuals, and compares the relative effects of ED manipulated by dietary fat only, fat and fiber, water, and type of sweetener. In short-term studies, consumption of low-ED foods promotes satiety, reduces hunger, and decreases energy intake with no marked differences between different dietary manipulations used to change ED. In addition, low-ED diets promote moderate weight loss in long-term studies. In studies lasting longer than 6 months, weight loss was more than three times as great in individuals consuming diets both low in fat and high in fiber compared with diets only low in fat (-3.4 kg versus -1.0 kg). Combined, these studies suggest that diets low in fat and high in fiber may be the most effective low-ED diets for promoting weight loss. Further research is needed on the effects of dietary ED by changing water or sweetener content.

Body Composition↗
PubMed2001

The new childhood growth charts.

New childhood growth percentiles have been published recently by the Centers for Disease Control and Prevention, and are designed to replace the widely used 1977 National Center for Heath Statistics percentiles. International definitions for overweight and obesity in childhood, based on the body mass index, also have been published. This review discusses appropriate uses of the new percentile charts and international definitions of overweight.

Adolescent↗
PubMed2001

Dietary fiber and weight regulation.

The influence of dietary fiber on energy regulation remains controversial. This review summarizes published studies on the effects of dietary fiber on hunger, satiety, energy intake, and body composition in healthy individuals. Under conditions of fixed energy intake, the majority of studies indicate that an increase in either soluble or insoluble fiber intake increases postmeal satiety and decreases subsequent hunger. When energy intake is ad libitum, mean values for published studies indicate that consumption of an additional 14 g/day fiber for >2 days is associated with a 10% decrease in energy intake and body weight loss of 1.9 kg over 3.8 months. Furthermore, obese individuals may exhibit a greater suppression of energy intake and body weight loss (mean energy intake in all studies was reduced to 82% by higher fiber intake in overweight/obese people versus 94% in lean people; body weight loss was 2.4 kg versus 0.8 kg). These amounts are very similar to the mean changes in energy intake and body weight changes observed when dietary fat content is lowered from 38% to 24% of energy intake in controlled studies of nonobese and obese subjects. The observed changes in energy intake and body weight occur both when the fiber is from naturally high-fiber foods and when it is from a fiber supplement. In view of the fact that mean dietary fiber intake in the United States is currently only 15 g/day (i.e., approximately half the American Heart Association recommendation of 25-30 g/day), efforts to increase dietary fiber in individuals consuming <25 g/day may help to decrease the currently high national prevalence of obesity.

Body Composition↗
PubMed2001

Peer, parent, and media influences on the development of weight concerns and frequent dieting among preadolescent and adolescent girls and boys.

OBJECTIVE: To assess prospectively the influence of peers, parents, and the media on the development of weight concerns and frequent dieting. DESIGN: Prospective cohort study. SETTING: Questionnaires mailed annually to participants throughout the United States. PARTICIPANTS: One-year follow-up of 6770 girls and 5287 boys who completed questionnaires in 1996 and 1997 and were between 9 and 14 years of age in 1996. MAIN OUTCOME MEASURE: Onset of high levels of concern with weight and dieting frequently to control weight. RESULTS: During 1 year of follow-up, 6% of girls and 2% of boys became highly concerned with weight and 2% of girls and 1% of boys became constant dieters. Peer influence was negligible. Independent of age and body mass index, both girls (odds ratio [OR]): 1.9; 95% confidence interval [CI]: 1.1-3.1) and boys (OR: 2.7; 95% CI: 1.1-6. 4) who were making a lot of effort to look like same-sex figures in the media were more likely than their peers to become very concerned with their weight. Moreover, both girls (OR: 2.3; 95% CI: 1.1-5.0) and boys (OR: 2.6; 95% CI: 1.1-6.0) who reported that their thinness/lack of fat was important to their father were more likely than their peers to become constant dieters. CONCLUSIONS: Our results suggest that parents and the media influence the development of weight concerns and weight control practices among preadolescents and adolescents. However, there are gender differences in the relative importance of these influences.

Adolescent↗
PubMed2000

A review of age-related changes in energy regulation and suggested mechanisms.

This review discusses recent studies on possible causes of weight loss in older individuals. Studies of the regulation of food intake suggest that aging is associated with an impairment in the regulation of food intake that inhibits appropriate short-term and long-term compensation for imposed alterations in energy intake. The combination of a reduced ability to regulate energy intake, decreased sensory specific satiety, and adverse social factors such as functional limitations, social isolation and depression, increases the risk of negative energy balance leading to weight loss in older individuals.

Aging↗
PubMed2000

cAMP delays beta-amyloid (25-35) induced cell death in rat cortical neurons.

Beta-amyloid (A beta) accumulation is believed to contribute to neuronal cell death in Alzheimer's disease. To understand the role of cAMP in the regulation of A beta induced cell death, we used 8-chlorophenylthio-cAMP (8-CPT-cAMP, a cAMP analog) to raise intracellular cAMP levels. Exposure of rat cortical neurons to A beta(25-35) resulted in a gradual increase in lactate dehydrogenase (LDH) over 48 h, which was preceded by a transient elevation in caspase-3-like activity. In the presence of 8CPT-cAMP, both caspase-3 activity and LDH release was significantly reduced. These data suggest that elevation of intracellular cAMP levels attenuate A beta-induced neurotoxicity and may delay or prevent the onset of A beta-induced neurodegeneration.

Amyloid beta-Peptides↗
PubMed2000

Cloning and characterization of prostaglandin endoperoxide synthase-1 and -2 from the brook trout ovary.

Using a combination of reverse transcription-PCR and library screening, the cDNAs for prostaglandin endoperoxide synthase-1 (PGS-1) and 2 (PGS-2) were isolated from the brook trout ovary. The brook trout PGS-1 cDNA encodes for a 598 amino acid protein that is 69% identical to mammalian PGS-1. PGS-1 transcripts were observed in the ovary, spleen, gills, head kidney, trunk kidney, intestine, stomach, skin and heart. To our knowledge, this is the first characterization of a non-mammalian PGS-1 cDNA. The brook trout PGS-2 encodes for a 607 amino acid protein that is 69% identical to mammalian PGS-2 and was observed in the skin, gills, stomach and heart. PGS-2 transcripts were highly upregulated in the ovaries by the phorbol ester, phorbol-12-myristate-13-acetate, in combination with the calcium ionophore, A23187. However, PGS-2 was not observed in the ovary of brook trout undergoing natural oocyte maturation and ovulation.

Amino Acid Sequence↗
PubMed2000

Regulation of energy intake in relation to metabolic state and nutritional status.

Inadequate energy intake can be an important contributor to weight loss in older individuals. This review highlights recent studies on possible causes of negative energy balance in older individuals. Studies of the regulation of food intake suggest that aging is associated with a significant impairment in the regulation of food intake that inhibits appropriate short-term and long-term compensation for imposed alterations in energy intake. The combination of a reduced ability to regulate energy intake, decreased sensory-specific satiety, and disadvantageous social factors such as functional limitations, social isolation and depression, increases the risk of negative energy balance leading to weight loss in older individuals.

Aged↗
PubMed2000

Psychological measures of eating behavior and the accuracy of 3 common dietary assessment methods in healthy postmenopausal women.

BACKGROUND: Factors affecting the accuracy of reported energy intake (rEI) need to be identified. OBJECTIVE: Our objective was to investigate the association of psychological measures of eating behavior with the accuracy of rEI assessed by 7-d weighed intakes, a 24-h recall, and a food-frequency questionnaire. DESIGN: Subjects were 26 restrained eaters aged 60.3 +/- 0.6 y (mean +/- SEM) and weighing 63.8 +/- 1.7 kg and 34 unrestrained eaters aged 59.4 +/- 0.6 y and weighing 64.0 kg. rEI was assessed by using 3 dietary assessment methods and total energy expenditure (TEE) was determined by using doubly labeled water. Calculated EI (cEI) was determined as TEE corrected for the estimated change in body energy. Subjects completed the Eating Inventory. RESULTS: rEI values were significantly lower than TEE values for all 3 dietary assessment methods (P < 0.05); there was no significant relation between rEI and TEE by any method. There was no significant difference in 100 x rEI:TEE between restrained and unrestrained eaters by any of the dietary assessment methods. When combined data from the 3 methods were used, 100 x rEI:cEI was not significantly different from 100% in unrestrained eaters (99 +/- 6.8%) but was lower in restrained eaters (89.1 +/- 5.3%; P < 0.05). There was a positive relation between hunger and 100 x rEI:TEE (P < 0.05). CONCLUSIONS: Low hunger is associated with undereating relative to normal eating during measurement of dietary intake; high dietary restraint may be associated with a reduction in reporting of consumed foods. Dietary hunger and restraint assessed with use of the Eating Inventory may help to identify subjects likely to underreport dietary intake.

Body Weight↗
PubMed2000

Why are nutritionally stunted children at increased risk of obesity? Studies of metabolic rate and fat oxidation in shantytown children from São Paulo, Brazil.

BACKGROUND: Previous research suggested that nutritionally stunted children may have increased risk of obesity, but little is known about potential underlying mechanisms. OBJECTIVE: We sought to test the hypothesis that stunted children have a low metabolic rate and impaired fat oxidation relative to nonstunted children. DESIGN: The subjects were 58 prepubertal boys and girls aged 8-11 y from the shantytowns of São Paulo, Brazil. Twenty-eight were stunted (height-for-age z score <-1.5) and 30 had similar weight-for-height but normal height (height-for-age z score >-1.5). Parents of children in the 2 groups had equivalent height and body mass index values. Fasting and postprandial energy expenditure, respiratory quotient (RQ), and substrate oxidation were measured with indirect calorimetry in a 3-d resident study in which all food was provided and body composition was measured with dual-energy X-ray absorptiometry. RESULTS: Stunted children had normal resting energy expenditure relative to body composition compared with control children (4559 +/- 90 and 4755 +/- 86 kJ/d, respectively; P: = 0.14) and had normal postprandial thermogenesis (2.4 +/- 0.3% and 2.0 +/- 0.3% of meal load, respectively; P: = 0.42). However, fasting RQ was significantly higher in the stunted group (0.92 +/- 0.009 compared with 0.89 +/- 0.007; P: = 0.04) and consequently, fasting fat oxidation was significantly lower (25 +/- 2% compared with 34 +/- 2% of energy expenditure; P: < 0.01). CONCLUSIONS: Childhood nutritional stunting is associated with impaired fat oxidation, a factor that predicted obesity in other at-risk populations. This finding may help explain recent increases in body fatness and the prevalence of obesity among stunted adults and adolescents in developing countries.

Body Composition↗
PubMed2000

Energy expenditure of stunted and nonstunted boys and girls living in the shantytowns of São Paulo, Brazil.

BACKGROUND: Stunting increases the risk of obesity in developing countries, particularly in girls and women, but the underlying reason is not known. OBJECTIVE: Our objective was to test the hypothesis that stunted children have lower energy expenditure than do nonstunted children, a factor that has predicted an increased risk of obesity in other high-risk populations. DESIGN: A cross-sectional study was conducted in shantytown children from São Paulo, Brazil. Twenty-eight stunted children aged 8-11 y were compared with 30 nonstunted children with similar weight-for-height. Free-living total energy expenditure (TEE) was measured over 7 d by using the doubly labeled water method. In addition, resting energy expenditure (REE) was measured by indirect calorimetry and body composition was measured by dual-energy X-ray absorptiometry. RESULTS: There were no significant associations between stunting and any measured energy expenditure parameter, including REE adjusted for weight (f1.gif" BORDER="0"> +/- SEM: 4575 +/- 95 compared with 4742 +/- 91 kJ/d, in stunted and nonstunted children, respectively) and TEE adjusted for weight (8424 +/- 239 compared with 8009 +/- 221 kJ/d, in stunted and nonstunted children, respectively). In multiple regression models that included fat-free mass and fat mass, girls had significantly lower TEE than did boys (P: < 0.05) but not significantly lower REE (P: = 0.17). CONCLUSIONS: There was no association between stunting and energy expenditure after differences between groups in body size and composition were accounted for. However, the girls had lower TEE than did boys, which may help to explain the particularly high risk of obesity in stunted adolescent girls and women in urban areas of developing countries.

Absorptiometry, Photon↗
PubMed2000

Effects of a 6-week hypocaloric diet on changes in body composition, hunger, and subsequent weight regain in healthy young and older adults.

Recent studies have suggested a short-term impairment in the regulation of food intake in older adults, but further studies are needed to determine if a longer-term impairment exists and to identify underlying causes. Changes in body weight and composition were measured over a 6-week underfeeding study and a 6-month follow-up period in healthy young (n = 23) and older (OLD, n = 18) men and women. The young adults were either normal weight (YNW, n = 12) or overweight (YOW, n = 11). Energy intakes during underfeeding were 896 +/- 18 (SEM) kcal less than weight-maintenance energy requirements determined prior to underfeeding. In addition, changes in perceived hunger during underfeeding were monitored in a subgroup (n = 19). OLD and YOW subjects lost significantly more weight during underfeeding than did YNW subjects (p = .025 and .000, respectively), and they did not gain back significant weight in the 6-month follow-up. In addition, OLD subjects reported a significantly lower frequency of hunger during underfeeding (p = .05). There was no significant difference among groups in the relationship between weight lost and fat-free mass lost. Healthy OLD adults have an impaired ability to regulate food intake over at least 6 months following underfeeding compared with YNW adults, and a reduction in their perceived frequency of hunger may be a contributing factor.

Adult↗
PubMed2000

Dietary determinants of energy intake and weight regulation in healthy adults.

Until recently, the percentage of energy from dietary fat has been considered a primary determinant of body fatness. This review covers recent studies from our laboratory that challenge this notion. High and low fat diets matched for energy density, palatability and fiber resulted in similar mean voluntary energy intakes over 9 d; analysis of the individual foods in these diets showed that energy density and palatability were significant determinants of energy intake, independent of fat content. Path analysis further revealed that the influence of energy density on energy intake was in part direct, and in part indirect and mediated by palatability. In another study, dietary variety within food groups was shown to be an important predictor of body fatness, and the direction of the association depended on which food groups provided the variety, i.e., the variety of sweets, snacks, condiments, entrees and carbohydrates consumed was positively associated with body fatness, whereas the variety of vegetables was negatively associated. Last, a study of restaurant food and body fatness showed that the frequency of consumption of restaurant food was positively associated with body fatness, independent of education level, smoking status, alcohol intake and physical activity. Restaurant meals tend to be high in fat and low in fiber, and thus energy dense. Restaurants also typically serve a variety of palatable foods in large portions. The increasing variety of high energy foods available and the increasing proportion of household income spent on foods consumed away from home may help explain the U.S. national rising prevalence of obesity.

Adult↗
PubMed2000

Regulation of energy intake may be impaired in nutritionally stunted children from the shantytowns of São Paulo, Brazil.

We tested the hypothesis that nutritionally stunted children have impaired regulation of energy intake (EI), a factor that could help explain the increased risk of obesity associated with stunting in developing countries. A 3-d residency study was conducted in 56 prepubertal boys and girls aged 8-11 y from the shantytowns of Sao Paulo, Brazil. Twenty-seven of the subjects were stunted and 29 were not stunted; weight-for-height Z-scores were not significantly different between the groups. Parents of the two groups had equivalent heights and body mass indices. Measurements were made of voluntary EI from a self-selection menu, resting energy expenditure (REE) and body composition. In addition, a 753-kJ yogurt supplement was administered at breakfast on one study day (with an equal number of children receiving the supplement on each of the 3 study days) and its effect on daily EI assessed. There was no change in EI over time in either group (P: = 0.957), and no significant difference in EI between stunted and nonstunted children, even though the stunted children weighed 10% less. Energy intake per kilogram body weight was significantly higher in the stunted children (278 +/- 89 (SD), vs. 333 +/- 67 kJ/kg, P: < 0.05) and EI/REE was also significantly higher (1.91 +/- 0.34 vs. 1.68 +/- 0.38, P: < 0.05). However, the relationship between EI and body weight was not significantly influenced by stunting (P: = 0.12). There was no significant effect of the breakfast supplement on daily EI in either group although the absolute difference in EI between supplement and control days was greater in stunted than in nonstunted children (DeltaEI: +460 +/- 1574 vs. -103 +/- 1916 kJ/d, P: = 0.25). These data provide preliminary evidence consistent with the suggestion that stunted children tend to overeat opportunistically, but further studies are required to confirm these results in a larger study.

Basal Metabolism↗
PubMed2000

Micronutrient shortfalls in young children's diets: common, and owing to inadequate intakes both at home and at child care centers.

Numerous studies documented low intakes of iron, zinc, calcium, and other micronutrients in young children. A recent report suggests that intakes are low in both home food and food provided at day care centers. Most of the young children in that study could not have obtained adequate intakes of key micronutrients without major dietary changes. Is it time to recommend routine multivitamin/mineral supplementation for all young children?

Child Day Care Centers↗
PubMed2000

Holiday weight gain: fact or fiction?

The prevalence of obesity continues to rise and controversy remains regarding the underlying specific causes of this trend. Recently, the magnitude of holiday weight gain and its contribution to annual weight gain were examined in a convenience sample of 195 adults. On average, weight gain during the 6-week winter period from Thanksgiving through New Year averaged only 0.37 kg. However, weight gain was greater among individuals who were overweight or obese, and 14% gained >2.3 kg (5 lb). In addition, among the entire population, weight gain during the 6-week holiday season explained 51% of annual weight gain. These results suggest that holiday weight gain may be an important contributor to the rising prevalence of obesity, even though absolute values for weight gain in this study were less than anticipated. Further studies using representative populations are needed to confirm these findings.

Holidays↗