Antegrade intravenous catheterization for metabolic studies in man.
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Blood Glucose↗
Biomedical subjects
C B Ebbeling
Publications and source records attributed to C B Ebbeling.
Should obese patients be counselled to follow a low-glycaemic index diet? Yes.
A reduction in dietary fat has been widely advocated for the prevention and treatment of obesity and related complications. However, the efficacy of low-fat diets has been questioned in recent years. One potential adverse effect of reduced dietary fat is a compensatory increase in the consumption of high glycaemic index (GI) carbohydrate, principally refined starchy foods and concentrated sugar. Such foods can be rapidly digested or transformed into glucose, causing a large increase in post-prandial blood glucose and insulin. Short-term feeding studies have generally found an inverse association between GI and satiety. Medium-term clinical trials have found less weight loss on high GI or high glycaemic load diets compared to low GI or low glycaemic load diets. Epidemiological analyses link GI to multiple cardiovascular disease risk factors and to the development of cardiovascular disease and type 2 diabetes. Physiologically orientated studies in humans and animal models provide support for a role of GI in disease prevention and treatment. This review examines the mechanisms underlying the potential benefits of a low GI diet, and whether such diets should be recommended in the clinical setting.
Cardiovascular Diseases↗
Type 2 diabetes mellitus in children: primary care and public health considerations.
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Child↗
Sources of variance in daily physical activity levels in the seasonal variation of blood cholesterol study.
The authors examined sources of variance in self-reported physical activity in a cohort of healthy adults (n = 580) from Worcester, Massachusetts (the Seasonal Variation of Blood Cholesterol Study, 1994-1998). Fifteen 24-hour physical activity recalls of total, occupational, and nonoccupational activity (metabolic equivalent-hours/day) were obtained over 12 months. Random effects models were employed to estimate variance components for subject, season, day of the week, and residual error, from which the number of days of assessment required to achieve 80% reliability was estimated. The largest proportional source of variance in total and nonoccupational activity was within-subject variance (50-60% of the total). Differences between subjects accounted for 20-30% of the overall variance in total activity, and seasonal and day-of-the-week effects accounted for 6% and 15%, respectively. For total activity, 7-10 days of assessment in men and 14-21 days of assessment in women were required to achieve 80% reliability. For nonoccupational activity, 21-28 days of assessment were required. This study is among the first to have examined the sources of variance in daily physical activity levels in a large population of adults using 24-hour physical activity recall. These findings provide insight for understanding the strengths and limitations of short term and long term physical activity assessments employed in epidemiologic studies.
Activities of Daily Living↗
Seasonal variation in household, occupational, and leisure time physical activity: longitudinal analyses from the seasonal variation of blood cholesterol study.
The authors examined seasonal variation in physical activity in longitudinal analyses of 580 healthy adults from Worcester, Massachusetts (the Seasonal Variation of Blood Cholesterol Study, 1994-1998). Three 24-hour physical activity recalls administered five times during 12 months of follow-up were used to estimate household, occupational, leisure time, and total physical activity levels in metabolic equivalent (MET)-hours/day. Trigonometric models were used to estimate the peak-to-trough amplitude and phase of the peaks in activity during the year. Total activity increased by 1.4 MET-hours/day (121 kcal/day) in men and 1.0 MET-hours/day (70 kcal/day) in women during the summer in comparison with winter. Moderate intensity nonoccupational activity increased by 2.0-2.4 MET-hours/day in the summer. During the summer, objectively measured mean physical activity increased by 51 minutes/day (95% confidence interval: 20, 82) in men and by 16 minutes/day (95% confidence interval: -12, 45) in women. The authors observed complex patterns of seasonal change that varied in amplitude and phase by type and intensity of activity and by subject characteristics (i.e., age, obesity, and exercise). These findings have important implications for clinical research studies examining the health effects of physical activity and for health promotion efforts designed to increase population levels of physical activity.
Adult↗
Facilitating dietary change: the patient-centered counseling model.
Recent data indicate that the patient-centered counseling model enhances long-term dietary adherence. This model facilitates change by assessing patient needs and subsequently tailoring the intervention to the patient's stage in the process of change, personal goals, and unique challenges. This article describes this model, including its theoretical foundations, a 4-step counseling process, and applications. This behavioral counseling model can help nutrition professionals enhance patient adherence to nutrition care plans and dietary guidelines.
Behavior Therapy↗
Change in women's diet and body mass following intensive intervention for early-stage breast cancer.
OBJECTIVE: To determine the effectiveness of an intensive dietary intervention on diet and body mass in women with breast cancer. DESIGN: Randomized clinical trial. SUBJECTS: 172 women aged 20 to 65 years with stage I or II breast cancer. INTERVENTION: A 15-session, mainly group-based and dietitian-led nutrition education program (NEP) was compared to a mindfulness-based stress reduction clinic program (SRC); or usual supportive care (UC). MAIN OUTCOME MEASURES: Dietary fat, complex carbohydrates, fiber, and body mass were measured. STATISTICAL ANALYSIS: In addition to descriptive statistics, analysis of variance was conducted to test for differences according to intervention group. RESULTS: Of the 157 women with complete dietary data at baseline, 149 had complete data immediately postintervention (at 4 months) and 146 had complete data at 1 year. Women randomized to NEP (n = 50) experienced a large reduction in fat consumption (5.8% of energy as fat) at 4 months and much of this reduction was preserved at 1 year (4.1% of energy) (both P < .0002) vs no change in either SRC (n = 51) or UC (n = 56). A 1.3-kg reduction in body mass was evident at 4 months in the NEP group (P = .003) vs no change in the SRC and UC groups. Women who had higher-than-average expectations of a beneficial effect of the intervention experienced larger changes. APPLICATIONS: Dietitians' use of group nutrition interventions appear to be warranted. Increasing their effectiveness and maintaining high levels of adherence may require additional support, including the involvement of significant others, periodic individual meetings, or group booster sessions.
Adult↗
Treating obesity in youth: should dietary glycemic load be a consideration?
Although the adverse effects of excess adiposity on health outcomes are widely recognized, there is no consensus regarding the most appropriate dietary strategies for managing obesity in youth. Recently, a novel dietary variable termed glycemic load has been postulated to influence hunger and body weight regulation. Glycemic load, a measure of the effects of a meal on blood glucose levels, is determined by the type and the amount of carbohydrate consumed. According to a hypothetical model, ingestion of high-glycemic load meals induces a sequence of hormonal changes that alter partitioning of metabolic fuels, exacerbate hunger, and over the long-term, promote weight gain. This chapter provides an overview of the available evidence suggesting that dietary glycemic load, and its related factor, the glycemic index, should be taken into consideration in the design of weight loss interventions.
Adolescent↗
Sources of variability in dietary intake in two distinct regions of rural India: implications for nutrition study design and interpretation.
OBJECTIVE: Limited inter-person variability in nutrient intake hampers epidemiologic studies of diet-disease relationships. Despite conjecture about non-traditional study bases providing large inter-person differences, virtually nothing is known about variations in nutrient intake outside of Europe and North America. The current study was conducted in India to determine sources of variability in the intakes of nutrients thought to be of public health importance. DESIGN: Adult subjects in Gujarat (North India; n=60) and in Kerala (South India, n=60) were administered 24 h diet recall interviews six and eight times, respectively, over a 1 y period. To assess subject (inter-person) and residual (intra-person) contributions to variance, regression models were fit to the data. From this, the variance ratio (VR, total within or intra-person: total between or inter-person) was computed. SETTING: Rural communities in North and South India. RESULTS: In both regions, inter-person variability was larger than that observed in the West. This was most pronounced in Gujarat, for which the VR was <1.0 for seven of the 12 energy-adjusted nutrient intakes in both men and women. In analyses of the combined data, region accounted for >20% of variance for fat, iron, copper, zinc, beta-carotene and riboflavin in both men and women. With the region term removed from this model, virtually all of the variability ascribed to region contributed to inter-person variability. CONCLUSIONS: The relatively large inter-person variability observed here could contribute to improved 'resolution' of diet-outcome relationships in epidemiologic studies. While this applies to data from each region, it was especially evident in analyses of the combined data.
Adult↗
A dietitian-delivered group nutrition program leads to reductions in dietary fat, serum cholesterol, and body weight: the Worcester Area Trial for Counseling in Hyperlipidemia (WATCH).
OBJECTIVE: To assess the effectiveness of a dietitian-based nutrition counseling and education program for patients with hyperlipidemia. DESIGN: A 4-session program implemented as a complement to a randomized physician-delivered intervention. SUBJECTS/SETTING: From 12 practice sites of the Fallon Clinic, 1,162 subjects with hyperlipidemia were recruited, 645 of whom had data sufficient for our primary analyses. INTERVENTION: Two individual and 2 group sessions conducted over 6 weeks. MAIN OUTCOME MEASURES: Total and saturated fat levels; serum low-density lipoprotein cholesterol levels; and body weight, measured at baseline and after 1 year. STATISTICAL ANALYSES: Multiple linear regression was used to evaluate changes in outcome measures. RESULTS: After 1 year, there were significant reductions in outcome measures for subjects attending 3 or 4 nutrition sessions vs subjects attending fewer than 3 sessions or those never referred to a nutrition session. Reductions (mean +/- standard error) in saturated fat (measured as percent of energy) were 2.7 +/- 0.5%, 2.1 +/- 0.5%, and 0.3 +/- 0.1%, respectively. These reductions correspond to roughly a 22% relative change from baseline in those attending 3 or 4 sessions. Corollary reductions were observed for total fat (measured as percent of energy): 8.2 +/- 1.4%, 5.0 +/- 1.4%, and 0.7 +/- 0.4%; low-density lipoprotein cholesterol: 0.48 +/- 0.11 mmol/L, 0.13 +/- 0.11 mmol/L, and 0.02 +/- 0.03 mmol/L; and body weight: 4.5 +/- 0.9 kg, 2.1 +/- 0.8 kg, and 1.1 +/- 0.2 kg. The specified changes were additive to those of the physician-delivered intervention. APPLICATIONS/CONCLUSIONS: This investigation provides empirical data demonstrating the effectiveness of a dietitian-delivered intervention in the care of patients with hyperlipidemia.
Adult↗
Effects of exercise combined with diet therapy on protein utilization in obese children.
PURPOSE: Hypocaloric therapy may adversely affect protein utilization in obese children given that metabolic reactions involving protein, a nutrient essential for growth, are energy-dependent. Because physical activity influences nutrient utilization and may modulate the effects of reduced energy intake, exercise combined with diet therapy may be beneficial with regard to protein metabolism. The primary purpose of this study was to evaluate changes in protein utilization in response to sequential addition of an exercise program to dietary intervention in obese children. METHODS: After a 2-wk baseline period, five subjects aged 8-10 yr reduced energy intake [-2092 to -2510 kJ.d(-1)(-500 to -600 kcal.d(-1))] for 12 wk. A walking program [5 d.wk(-1), 3.2-4.8 km.d(-1) (2-3 miles.d(-1))] was implemented during the final 6 wk of diet therapy. At baseline and after phases I (diet only) and II (exercise and diet) of intervention, 15N-glycine was used to assess protein synthesis (PS), protein breakdown (PB), net turnover (NET = PS - PB), and nitrogen flux (Q). RESULTS: Subjects lost 4.2+/-0.4 kg during the 12-wk intervention period (P < or = 0.05). With diet only, NET decreased (P < or = 0.05) due to a reduction in PS (P < or = 0.05) accompanied by no change in PB. Although PS increased with walking (P < or = 0.05), NET did not return to baseline levels due to a concurrent increase in PB (P < or = 0.05). Changes in PS and PB yielded an increase in Q (P < or = 0.05), a measure of amino acid cycling between protein and free amino acid pools. CONCLUSIONS: These results suggest that exercise offers metabolic benefits for obese children during diet-induced weight loss. Longitudinal studies are needed to assess long-term health outcomes associated with the observed changes in protein utilization.
Body Composition↗
Effects of reduced energy intake on protein utilization in obese children.
Dietary treatment of pediatric obesity is a challenge given the need for adequate nutrients to support the maintenance of lean tissue and growth. The primary purpose of this investigation was to assess the effects of reduced energy intake on protein turnover in obese children aged 8 to 10 years. Following a 2-week baseline period, 16 subjects reduced energy intake during a 6-week intervention period. At baseline and following the intervention, 15N-glycine methodology was used to measure nitrogen flux (Q), protein synthesis (PS), protein breakdown (PB), and net turnover ([NET] PS - PB). Other criterion measures included resting metabolic rate (RMR), fat mass (FM), fat-free mass (FFM), urinary creatinine to height ratio (Cr:Ht), and nitrogen balance (NB). On average, subjects lost 2.2 +/- 0.3 kg, of which greater than 85% was FM. Decreased Q (P = .03) indicated downregulation of protein turnover in response to diet-induced weight loss. While PB did not change, NET declined slightly (P = .06) as a consequence of reduced PS (P = .03). Reductions in FFM (P = .09), Cr:Ht (P = .02), and NB (P = .03) accompanied alterations in protein turnover, but there was no change in the RMR. In conclusion, while short-term therapy promoted the loss of FM and did not compromise RMR, practitioners must be cautious when prescribing diets, given the observed changes in protein utilization and somatic protein status. Longitudinal studies are needed to further characterize the metabolic responses of obese children to long-term diet therapy.
Amino Acids↗
Chronic psychological effects of exercise and exercise plus cognitive strategies.
Psychological changes associated with 16-wk moderate and low intensity exercise training programs, two of which possessed a cognitive component, were evaluated. Subjects were healthy, sedentary adults, 69 women (mean age = 54.8 +/- 8.3 yr) and 66 men (mean age = 50.6 +/- 8.0 yr). Participants were randomly assigned to a control group (C), moderate intensity walking group (MW), low intensity walking group (LW), low intensity walking plus relaxation response group (LWR), or mindful exercise (ME) group-a Tai Chi type program. Women in the ME group experienced reductions in mood disturbance (tension, P < 0.01; depression, P < 0.05; anger, P < 0.008; confusion, P < 0.02; and total mood disturbance, P < 0.006) and an improvement in general mood (P < 0.04). Women in the MW group noted greater satisfaction with physical attributes (body cathexis, P < 0.03), and men in MW reported increased positive affect (P < 0.006). No other differences were observed between groups on measures of mood, self-esteem, personality, or life satisfaction. Equivocal support is provided for the hypothesis that exercise plus cognitive strategy training programs are more effective than exercise programs lacking a structured cognitive component in promoting psychological benefits.
Adaptation, Psychological↗
Development of a single-stage submaximal treadmill walking test.
An equation was developed to estimate maximal oxygen uptake (VO2max, ml.kg-1.min-1) based on a single submaximal stage of a treadmill walking test. Subjects (67 males, 72 females) aged 20-59 yr completed 4-min stages at 0, 5, and 10% grades walking at a constant speed (2.0-4.5 mph) and then performed a VO2max test. Heart rate and respiratory gas exchange variables were measured during the test. Multiple regression analysis (N = 117) to estimate VO2max from the 4-min stage at 5% grade yielded the following model (R2 = 0.86; SEE = 4.85 ml.kg-1.min-1): VO2max = 15.1 + 21.8*SPEED (mph) -0.327*HEART RATE (bpm) -0.263*SPEED*AGE (yr) + 0.00504*HEART RATE*AGE + 5.98*GENDER (0 = Female; 1 = Male). The constant and all coefficients were highly significant (P less than 0.01). To assess the accuracy of the model in a cross-validation group (N = 22), an estimated VO2max value was obtained using the above model. Estimated VO2max then was regressed on observed VO2max yielding the following equation (R2 = 0.92): ESTIMATED VO2max = 0.15 + 1.03*OBSERVED VO2max. The intercept and slope of this equation were not significantly different from 0 and 1, respectively. For 90.9% of the subjects in the cross-validation group, residual scores were within the range of +/- 5 ml.kg-1.min-1. In conclusion, this submaximal walking test based on a single stage of a treadmill protocol provides a valid and time-efficient method for estimating VO2max.
Adult↗
Muscle adaptation prior to recovery following eccentric exercise.
The effects of performing a second eccentric exercise bout prior to and after recovery from the first bout were compared. Twenty subjects performed 70 eccentric actions with the forearm flexors. Group A (n = 9) and group B (n = 11) repeated the same exercise 5 and 14 days after the initial bout, respectively. Dependent variables included muscle soreness, elbow joint angles, isometric strength, and serum creatine kinase (SCK). Subjects were tested pre-exercise and up to day 5 following each bout. The first bout produced significant changes in all measures for both groups (P less than 0.01). Values remained significantly different from baseline on day 5 when group A repeated the exercise (P less than 0.01) but were back to normal when group B performed bout 2. For both groups an adaptation occurred; significantly smaller changes in dependent variables were produced by the second bout, and recovery time was faster whether or not muscles were fully restored (P less than 0.01). The repeated bout did not exacerbate soreness, performance decrements, and elevation of SCK when performed by affected muscles that had not fully recovered from the first bout. Thus, the results suggest that an adaptation response had taken place prior to full recovery and restoration of muscle function following the initial eccentric exercise bout.
Adaptation, Physiological↗
Exercise-induced muscle damage and adaptation.
Novel, unaccustomed exercise has been shown to result in temporary, repairable skeletal muscle damage. After exhaustive endurance exercise, muscle damage can be produced by metabolic disturbances associated with ischaemia. Extensive disruption of muscle fibres also occurs after relatively short term eccentric exercise where high mechanical forces are generated. Biopsies taken after repetitive eccentric muscle actions have revealed broadening, streaming and, at times, total disruption of Z-discs. Muscles that develop active tension eccentrically also become sore, lose inherent force-producing capability, and show a marked release of muscle proteins into the circulation. Because creatine kinase (CK) is found almost exclusively in muscle tissue, it is the most common plasma marker of muscle damage. Despite the universal use of CK as a marker, several factors with regard to efflux and clearance remain unexplained. Also the large intersubject variability in response to exercise complicates its interpretation. Damage progresses in the postexercise period before tissues are repaired. However, the mechanism to explain exercise-induced muscle damage and repair is not well defined. Among the factors that may influence the damage and repair processes are calcium, lysosomes, connective tissue, free radicals, energy sources, and cytoskeletal and myofibrillar proteins. Physical conditioning results in an adaptation such that all indicators of damage are reduced following repeated bouts of exercise. Recently, investigators have suggested that the prophylactic effect of training may be due to performance of a single initial exercise bout. Following a second bout of exercise performed 1 to 6 weeks after the first bout, there is a reduction in morphological alterations and performance decrements and a profoundly reduced elevation in plasma CK levels. Several hypotheses have been presented to explain the repeated bout or rapid training effect. Stress-susceptible fibres may be eliminated or susceptible areas within a fibre may undergo necrosis and then regenerate. These regenerated fibres, along with adaptations in the connective tissue, may provide greater resistance to further insult.
Adaptation, Physiological↗
Walking for exercise testing and training.
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Adult↗