Biomedical subjects

K R Westerterp

Publications and source records attributed to K R Westerterp.

At least 127 records · Page 7Linked to original sources

PubMed1995

Effect of variable protein intake on whole-body protein turnover in young men and women.

The effect of the amount of protein intake (12% and 21% of total energy intake, diet A and diet B, respectively) on nitrogen balance and whole-body protein turnover (PT) was measured in 19 young men and 10 young women (aged 30 +/- 5 and 27 +/- 4 y, respectively). In young adults, mean nitrogen balance was approximately zero during diet A whereas it was positive during diet B. In young adults, PT was significantly higher during diet B in comparison with diet A. This was also seen in elderly subjects, as described before. From a comparison of the current data with the data previously obtained in elderly subjects it can be concluded that during diet A young adults had PT rates higher than those of elderly subjects. During diet B, PT of young men was comparable with the PT of elderly men whereas young women still had higher PT rates than elderly women (even when corrections were made for differences in body composition).

Adult↗

PubMed1995

The use of bioelectrical impedance analysis to predict total body water in patients with cancer cachexia.

The applicability of bioelectrical impedance analysis (BIA) to predict total body water (TBW) was assessed in 16 underweight [< 95% of ideal body weight (IBW)] and 25 normal-weight (> 95% of IBW) cancer patients. Although height2/resistance (ht2/R) proved to be a strong single predictor of TBW measured by deuterium dilution in both groups (normal-weight patients: r2 = 0.85, SEE 2.16 L; underweight patients: r2 = 0.86, SEE 2.24 L), TBW would be significantly overestimated in the underweight group if the prediction formula developed in the normal-weight group was used [bias 1.67 L (5%), 95% CI 0.20-3.15 L]. A systematic overestimation of TBW in the underweight patients was also found when TBW was predicted in our two patient groups by several previously published BIA formulas developed in normal-weight individuals. We conclude therefore, that although a similar relationship is found between ht2/R and TBW in normal-weight and underweight cancer patients, single-frequency BIA overestimates TBW in underweight patients when prediction formulas are used that have been developed in normal-weight subjects.

Adenocarcinoma↗

PubMed1995

Energy balance during an 8-wk energy-restricted diet with and without exercise in obese women.

The effects of severe energy restriction alone (2.0 MJ/d for 4 wk and subsequently 3.5 MJ/d for 4 wk) or energy restriction plus moderate exercise on energy balance were studied in 20 healthy obese women. Subjects aged 25-50 y were matched on the basis of body mass index and percentage body fat and randomly assigned to diet alone (D) or diet and exercise (DE) for 8 wk. DE resulted in a significantly increased loss of fat mass compared with D (7.8 +/- 0.8 compared with 5.5 +/- 0.8 kg; P < 0.05). The average daily metabolic rate measured with doubly labeled water decreased with both treatments, with no differences between the treatments. Energy balance data show that the DE treatment resulted in a significantly greater energy deficit than the D treatment. The relative contribution of fat to energy expenditure during exercise was significantly enhanced by DE treatment whereas it did not change after D. The energy expended on physical activity was not changed at the end of both treatments, with no differences between the two groups. The unchanged energy expended on physical activity indicates that DE might be accompanied by partial compensation of daily physical activities outside the training for the energy expended during the training. The energy deficit due to energy restriction alone was not compensated by a decrease in free-living daily physical activities. Addition of moderate exercise to an energy-restriction program in obese women has advantages with respect to changes in body composition, energy expenditure, and substrate utilization.

Adult↗

PubMed1995

Energy expenditure and substrate metabolism in patients with cirrhosis of the liver: effects of the pattern of food intake.

Patients with liver cirrhosis are often undernourished. In healthy subjects, the pattern of food intake is one of the variables that can influence energy balance and substrate metabolism. The short term (two day) effect of the pattern of food intake in patients with cirrhosis and controls was compared. In a respiration chamber, eight patients with cirrhosis of the liver and 23 controls were fed to estimated energy balance in two meals daily ('gorging' pattern) and four to seven meals daily ('nibbling' pattern). Twenty four hour energy expenditure, expressed as a multiple of the sleeping metabolic rate, was reduced in patients with cirrhosis (1.31 (0.03) v 1.44 (0.02) for controls; p < 0.01) because of an increased sleeping metabolic rate per kg fat free mass in these patients. In both patients and controls, the respiratory quotient was significantly lower during the morning preprandial period (9.00-12.00) on the gorging pattern, reflecting a higher oxidation ratio of fat to carbohydrate compatible with a more catabolic state. For patients with cirrhosis, a nibbling pattern of food intake, including a good breakfast and a late evening meal, would be preferable, in order to have shorter episodes of catabolism during the day.

Adult↗

PubMed1995

Measurement of fat-free mass in infants.

Body composition data are important for adequate monitoring of growth and nutritional status in infants. 18O Isotope dilution techniques (ID18-O) are widely used to estimate total body water (TBW) and calculate fat-free mass (FFM). A problem of isotope dilution is an underestimation of TBW by the extrapolation to t = O approach and an overestimation of TBW by the plateau approach. Using total body electrical conductivity (TOBEC) as the reference technique we validated the extrapolation approach by 149 measurements (boys, n = 76; girls, n = 73) in 50 healthy infants aged 1-12 mo. TOBEC-derived FFM and fat mass were in excellent agreement with Fomon's reference data. Strictly linear relationships with slopes not significantly different from one were found between FFM estimated by TOBEC (FFMTOBEC) and FFM estimated by ID18-O (FFM18-O) (r = 0.98 and residual SD = 0.29 for boys, r = 0.98 and residual SD = 0.32 for girls). FFM18-O was slightly but significantly lower than FFMTOBEC, the difference being on average 0.18 (+/- 0.24) kg for girls and 0.08 (+/- 0.21) kg for boys (i.e. respectively 4 (+/- 4.5)% (p < 0.0001) and 1.5 (+/- 3.9)% (p = 0.004) of FFMTOBEC). We conclude that ID18-O using the extrapolation to t = O approach is suitable for TBW and FFM estimations in groups of infants. Due to the considerable measurement error of ID18-O (estimated at approximately 6%), individual TBW18-O and FFM18-O estimates should be considered with some caution.

Anthropometry↗

PubMed1995

Impact of a moderately energy-restricted diet on energy metabolism and body composition in non-obese men.

OBJECTIVE: Since little information is available on the capacity of the non-obese to adapt to a moderate decrease in energy intake, the effect of a 10-week moderately energy-restricted diet (ER) on energy expenditure and body composition was studied. DESIGN: A controlled intervention study. After a weight-maintaining run-in period of 2 weeks, the ER group received a diet that contained 9.2 MJ/day on average, i.e. 80% of the energy of their habitual diet (estimated by means of a 7-day dietary record) for the next ten weeks while the control group received the weight-maintaining diet. SETTING: Subjects continued daily life habits and came to the Institute every evening to have dinner and to receive food for the next 24 h. SUBJECTS: 24 healthy non-obese, middle-aged men participated. Subjects were matched for age and body mass index and randomly assigned to a control group (n = 8) or an ER group (n = 16). RESULTS: Average daily metabolic rate (ADMR, i.e. total energy expenditure), measured with doubly labeled water in eight subjects of the ER group, appeared to be 82.5% of reported energy intake resulting in an actual level of energy restriction in these eight subjects of 33% on average (range 18-42%), rather than 20%. Subjects in the ER group lost 7.4 +/- 1.7 kg; 83% of this weight loss was fat mass, 17% was fat-free mass. Subjects in the control group lost some weight too (2.1 +/- 1.5 kg). Resting metabolic rate (RMR) (MJ/day) decreased in the ER group (P < 0.001). In this group the thyroid hormone triiodothyronine (T3) decreased (P < 0.001), while reverse T3 (rT3) increased (P < 0.05). ADMR decreased significantly. CONCLUSION: Under conditions of a controlled moderately energy-restricted diet in daily life a significant weight loss can be induced, similar to that observed after a balanced dietary deficit, providing 5 MJ/day. In addition, moderate energy restriction induces a decrease in fat-free mass and a fall in RMR.

Adult↗

PubMed1995

24 h energy expenditure during a standardized activity protocol in young and elderly men.

OBJECTIVE: The effect of age on energy expenditure was studied. DESIGN: Case-control study. SETTING: Respiration chamber at the University of Maastricht. SUBJECTS: Thirteen young men (27 +/- 4 years) and ten elderly men (74 +/- 5 years), were recruited with advertisements in local media. METHODS: In a 36 h experiment, 24 h energy expenditure (EE), sleeping metabolic rate (SMR), diet-induced thermogenesis (DIT) and energy expenditure of physical activity (EEact) were measured while subjects performed an activity protocol in a respiration chamber under strictly controlled conditions. RESULTS: SMR as a function of fat-free mass (FFM) was not different between both age groups. 24 h EE during a standardized activity protocol was significantly higher for the young men (young men: 12.85 +/- 1.53 MJ/d; elderly men: 10.90 +/- 1.12 MJ/d; P = 0.011). The DIT expressed as MJ/d was significantly higher for the young subjects but similar when expressed as percentage of energy intake (young men: 13.10 +/- 5.44%; elderly men: 9.88 +/- 3.86%). The resulting figure for EEact (24 h EE--SME--DIT) was the same for young and elderly men (young men: 3.11 +/- 0.71 MJ/d; elderly men: 3.05 +/- 0.64 MJ/d). CONCLUSION: The results indicate that mean energy costs for low intensity daily activities (some daily household activities and a bench stepping exercise) were the same for young and elderly men.

Adult↗

PubMed1995

Effect of weight-training on energy expenditure and substrate utilization during sleep.

This study was performed to investigate the effect of weight-training (12 wk; 21 male subjects) on energy expenditure and substrate utilization during sleep. Sleeping metabolic rate (SMR) as measured in a respiration chamber was calculated according to three procedures: the lowest mean energy expenditure of a shiftable 3-h interval between 0:00 and 6:00 (SMR3) and SMR over predetermined intervals from 3:00 to 6:00 (SMR3-6) and from 0:00 to 6:00 (SMR0-6). In analogy with SMR the corresponding respiratory quotients were expressed as RQ3, RQ3-6, and RQ0-6. Changes in body composition were assessed from changes in body weight, body volume (densitometry), and total body water (deuterium dilution). Weight-training induced an increase in fat-free mass (+1.1 +/- 1.3 kg; P < 0.001) and a decrease in fat mass (-2.3 +/- 1.5 kg; P < 0.001) and body weight (-1.1 +/- 2.1 kg; P < 0.05). There was no significant change in SMR, irrespective of the way SMR was expressed. Only RQ3 decreased significantly (from 0.82 +/- 0.04 to 0.79 +/- 0.02; P < 0.05). Remarkably RQ3, RQ3-6, and RQ0-6 were highly negative correlated with the pre-training RQ (r = -0.93, -0.91, and -0.90, respectively: P < 0.001) resulting in a diminished variation in post-training RQ (P < 0.001). These results suggest that weight-training has no effect on SMR but increases relative fat utilization in low fat oxidizers and vice versa for individuals displaying high pre-training lipid oxidation.

Adult↗

PubMed1994

Body mass, body composition and sleeping metabolic rate before, during and after endurance training.

Metabolic rate, more specifically resting metabolic rate (RMR) or sleeping metabolic rate (SMR), of an adult subject is usually expressed as a function of the fat-free mass (FFM). Chronic exercise is thought to increase FFM and thus to increase RMR and SMR. We determined body mass (BM), body composition, and SMR before, during, and after an endurance training programme without interfering with energy intake. The subjects were 11 women and 12 men, aged 37 (SD 3) years and body mass index 22.3 (SD 1.5) kg.m-2. The endurance training prepared subjects to run a half marathon competition after 44 weeks. The SMR was measured overnight in a respiration chamber. Body composition was measured by hydrostatic weighing. Measurements were performed at 0, 8, 20, 40, and 90 weeks after the start of the training. The BM had decreased from a mean value of 66.6 (SD 6.9) to 65.6 (SD 6.7) kg (P < 0.01), fat mass (FM) had decreased from 17.1 (SD 3.9) to 13.5 (SD 3.6) kg (P < 0.001), and FFM had increased from 49.5 (SD 7.3) to 52.2 (SD 7.6) kg (P < 0.001) at 40 weeks. Mean SMR before and after 40 weeks training was 6.5 (SD 0.7) and 6.2 (SD 0.6) MJ.day-1 (P < 0.05). The decrease in SMR was related to the decrease in BM (r = 0.62, P = 0.001). At 90 weeks, when most subjects had not trained for nearly a year, BM and SMR were not significantly different from the initial value while FM and FFM had not changed since week 40 of training.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1994

Substrate utilization in man: effects of dietary fat and carbohydrate.

In man there is evidence that the ability to adjust fat oxidation to fat intake is less effective than the ability to adjust carbohydrate and protein oxidation to carbohydrate and protein intake. The short-term (3-day) effects of a low-fat (LF), mixed (M), and high-fat (HF) diet on human substrate balances were studied using a respiration chamber. Subjects were 14 young female students classified by means of their scores on psychometric questionnaires as "restrained" or "unrestrained" eaters. Subjects were in energy balance, ie, the mean difference between energy intake (EI) and energy expenditure (EE) was 86 +/- 85 kJ/d. The fat content of the food significantly influence the 24-hour respiratory quotient (RQ) and nonprotein respiratory quotient (NPRQ). For both the LF and M diets, the 24-hour RQ was significantly lower than the food quotient (FQ), whereas the RQ on the HF diet was not different from the FQ. Oxidation of fat and carbohydrate significantly increased with, respectively, an increasing fat and carbohydrate content of the diet for both restrained- and unrestrained-eating subjects. Restrained-eating subjects showed a decreased fat oxidation compared with unrestrained eaters in response to a HF diet, resulting in a positive fat balance for restrained-eating subjects. On a LF diet, fat balance was negative for both groups of subjects, indicating net endogenous fat oxidation. In conclusion, restrained-eating subjects have more difficulty in the handling of a HF diet, possibly explaining their higher susceptibility to becoming obese.

Adult↗

PubMed1994

Deuterium dilution as a method for determining total body water: effect of test protocol and sampling time.

Deuterium dilution for the measurement of total body water (TBW) has been conducted using varying protocols for equilibration. We measured TBW from deuterium dilution in urine samples in twenty-eight subjects using three protocols: (1) early morning dosage without breakfast, measuring deuterium in a second voiding at 4 h and 6 h; (2) early morning dosage with breakfast with the same measurement times; (3) dosage as last consumption before overnight sleep, measuring deuterium in a second voiding at 10 h. Results were compared with TBW estimates from underwater weighing (UWW). Because UWW is an indirect measure of TBW, it is used as an independent reference method in order to compare only relative discrepancies between the two methods. TBW values in the fasted state were not significantly different from those obtained in the fed state. The urinary deuterium enrichment was higher at 4 h than at 6 h (resulting TBW differences: 0.6 (SD 0.4) l). At 4 h and 6 h, differences in TBW measurements from deuterium and densitometry were positively related to the amount of TBW, indicating incomplete equilibration in larger water compartments. At 10 h no such relationship existed, indicating complete mixing of deuterium. It is concluded that 10 h equilibration is preferable to the shorter 4 h and 6 h, for the determination of TBW.

Adult↗

PubMed1994

Between-laboratory comparison of densitometry and bio-electrical impedance measurements.

Body composition was measured in nine healthy, normal-weight, weight-stable subjects in three different research centres. In each centre the usual procedures for the measurements were followed. It revealed that the measurement procedures in the three centres were comparable. Body composition was measured in each centre between 09.00 and 13.00 hours after a light breakfast by densitometry (underwater weighing) and bio-electrical impedance. A single, total-body-water determination by D2O dilution was used as a reference value. Body fat determined by densitometry was significantly lower in one centre, which, however, could be completely explained by a lower body weight, probably due to water loss (the subjects refrained for a longer time from food and drinks before the measurements in that centre) and, thus, by violation of the assumptions of Siri's (1961) formula. Also, body impedance was slightly higher in that centre, indicating a lower amount of body water. Mean body fat from densitometry was also slightly lower in that centre compared with body fat determined by D2O dilution. Individual differences between body fat from densitometry and from total body water were relatively large, up to 7% body fat. The relationship between fat-free mass from densitometry and bio-electrical impedance was not different between the centres. It is concluded that differences in the relationship between body composition and bio-electrical impedance, as reported in the literature, may be due to differences in standardization procedures and/or differences in reference population.

Adipose Tissue↗

PubMed1994

Validation of bioelectrical-impedance measurements as a method to estimate body-water compartments.

Single-frequency bioelectrical-impedance analyses (BIA) and bioelectrical spectroscopy (modeling multifrequency measurements; BIS) were validated as methods to predict body water (BW) compartments in 29 healthy adults. Total body water (TBW) and extracellular water (ECW) were determined by deuterium- and bromide-dilution techniques. Contribution of BIA to anthropometry and influence of the position of electrodes were examined. Stepwise-regression analysis revealed that inclusion of BIA to anthropometric data greatly improved the fit with BW compartments. Highly significant correlations were observed between BIS and BW compartments (TBW: r2 = 0.98, SEE = 1.2; ECW: r2 = 0.95, SEE = 0.6). Cross-correlation (14 males, and 15 females) indicated predictive potential of the method. Results from BIS and BIA were comparable, but it is argued that BIS has the potential of improved standardization of the method.

Adult↗

PubMed1994

The influence of protein intake on vitamin B-6 metabolism differs in young and elderly humans.

Vitamin B-6 metabolism was studied as a function of dietary protein intake. Subjects were 29 young adults (29 +/- 1 y old) and 26 elderly adults (70 +/- 1 y old) who consumed standardized diets containing 12% (Diet A) and 21% (Diet B) of total energy as protein for 3 wk each, according to a randomized crossover design. Vitamin B-6 intake for young and elderly subjects was 1.52 +/- 0.08 mg/d (21.74 +/- 0.45 micrograms/g protein) and 1.47 +/- 0.05 mg/d (23.81 +/- 0.08 micrograms/g protein), respectively, during consumption of Diet A and 1.79 +/- 0.07 mg/d (14.49 +/- 0.11 micrograms/g protein) and 1.73 +/- 0.05 mg/d (16.24 +/- 0.06 micrograms/g protein) during consumption of Diet B. Plasma pyridoxal phosphate (PLP), pyridoxal and total vitamin B-6 concentrations were significantly lower in the elderly subjects compared with the young adult subjects during both diet periods. In the elderly subjects, PLP was significantly higher during Diet B consumption (Diet A: 27 +/- 3 nmol/L; Diet B: 32 +/- 3 nmol/L), whereas the level of protein intake had no significant effect on plasma PLP in the young adults (Diet A: 47 +/- 6 nmol/L; Diet B: 45 +/- 5 nmol/L). Plasma pyridoxal and plasma total vitamin B-6 concentrations were not influenced by the amount of protein intake in young and elderly subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Energy balance at high altitude of 6,542 m.

Weight loss due to malnutrition and possibly intestinal malabsorption is a well-known phenomenon in high-altitude climbers. Up to approximately 5,000 m, energy balance may be attained and intestinal energy digestibility remains normal. To see whether 1) energy balance may also be attained at 6,542 m and, if not, 2) whether decreased energy digestibility would play a significant role in the energy deficit, energy intake (EI), energy expenditure, body composition, and energy digestibility of 10 subjects (4 women, 6 men; 27-44 yr) were assessed during a 21-day sojourn on the summit of Mt. Sajama, Bolivia (6,542 m). EI was measured during two 3-day intervals: EI1 (days 7-9) and EI2 (days 17-19). Total fecal energy loss during EI1 was calculated from fecal energy measured by bomb calorimetry. Average daily metabolic rate (ADMR) at altitude was measured in six subjects (2 women, 4 men) using doubly labeled water over a 10-day interval (days 9-19). Basal metabolic rate was measured before and after the expedition by respiratory gas analysis. Body composition was estimated from skinfolds and body mass before and during the altitude sojourn. Subjects were in negative energy balance throughout the observation period (EI1-ADMR = -2.9 +/- 1.8 MJ/day and EI2-ADMR = -2.3 +/- 1.8 MJ/day based on a gross energy digestibility of 95%). The activity level, expressed as ADMR to basal metabolic rate, was 1.56-2.39. The loss of fat mass (3.7 +/- 1.5 kg) represented 74 +/- 15% of the loss of body mass.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗

PubMed1994

Effect of body build on weight-training-induced adaptations in body composition and muscular strength.

The aim of the present study was to investigate whether weight-training-induced adaptations in body composition and isokinetic strength differ as a function of body build. Body build of a subject was characterized as the extent to which a person's fat-free mass index (FFMI = fat-free mass.height-2;kg.m-2) differs from the regression of FFMI over fat mass index (FMI = fat mass.height-2;kg.m-2) as derived from a sedentary male population (N = 77). From this population two groups with either a slender (N = 10) or a solid (N = 11) body build were selected. For 12 wk the subjects performed a weight-training program twice a week. Training induced a significant (P < 0.05) increase in fat-free mass (FFM) in the solid group (1.6 kg, 2.3%) in contrast with the slender group, which showed no significant change in FFM. Both groups showed comparable decreases in fat mass (FM; slender: -1.7 kg, -10.8% versus solid: -2.4 kg, -11.3%) and increases in strength (on average 13.8%). In conclusion, the increase in FFM due to a weight-training program is modified by body build. This modification, however, is restricted to a larger increase in the solidly built group.

Adaptation, Physiological↗

PubMed1994

Energy balance in cross-country skiers: a study using doubly labeled water.

Energy intake covering energy expenditure is essential for performance as well as for health aspects in endurance athletes. This study was performed to determine the energy needs for elite cross country skiers during a week of training and to demonstrate whether energy balance could be maintained. Energy intake was calculated from weighed dietary records and doubly labeled water was used to simultaneously measure energy turnover. Average daily energy intake ranged from 15.7 to 20.4 MJ.d-1 in the females and from 25.7 to 36.0 MJ.d-1 in the males. This correlated well with the data for average daily energy turnover (r = 0.96; P = 0.0001) that ranged from 15.1 to 20.2 MJ.d-1 and from 25.4 to 34.9 MJ.d-1, in females and males, respectively. The mean difference being 0.1 (+/- 1.9) MJ.d-1. The close match between energy intake and energy expenditure has not previously been shown in athletes at these high levels of energy turnover. However, if energy intake over separate 24-h periods was compared with corresponding data for training, no significant relationship was found. This indicates that the athletes were not in energy balance during shorter periods. Furthermore, the validity of theoretical calculations of energy turnover, in highly trained subjects, derived from multiples of estimated BMR, is questioned.

Adult↗

PubMed1994

Assessment of energy expenditure for physical activity using a triaxial accelerometer.

A triaxial accelerometer was used to evaluate the relationship between energy expenditure due to physical activity (EEact) and body acceleration during different types of activity. In a laboratory experiment, 11 male subjects performed sedentary activities and walked on a motor driven treadmill (3-7 km.h-1). EEact was calculated from total energy expenditure (EEtot), as measured by indirect calorimetry, and sleeping metabolic rate (SMR): EEact = EEtot--SMR. Body accelerations were measured with a triaxial accelerometer at the low back. Special attention was paid to the analysis of unidirectional and three-directional accelerometer output. During sedentary activities a linear relationship between EEact and the sum of the integrals of the absolute value of accelerometer output from all three measurement directions (IAAtot) was found (r = 0.82, P < 0.001, Sy,x = 0.22 W.kg-1). During walking EEact was highly correlated with the integral of absolute accelerometer output in antero-posterior direction (IAAx; r = 0.96, P < 0.001, Sy,x = 0.53 W.kg-1). When all examined activities were included in a regression analysis, a strong linear relationship between EEact and IAAtot was found (r = 0.95, P < 0.001, Sy,x = 0.70 W.kg-1). Using this relationship, EEact during sedentary activities as well as EEact during walking could be estimated with an accuracy of about 15%. Although sedentary activities and walking represent a large part of normal daily physical activity, the validity and usefulness of the triaxial accelerometer--measuring IAAtot--to predict EEact in daily life must be studied under free-living conditions.

Acceleration↗