Biomedical subjects

K R Westerterp

Publications and source records attributed to K R Westerterp.

At least 109 records · Page 6Linked to original sources

PubMed1997

A long-term study on the effect of spontaneous consumption of reduced fat products as part of a normal diet on indicators of health.

The growing public concern with the adverse effects on health of a high fat intake has led to a proliferation on the market of reduced fat products. However, no consensus exists on the effectivity of reduced fat products to decrease energy intake. The studies that have investigated this topic have included small numbers of subjects, studied under laboratory conditions and over a relatively short period of time. Therefore, we have executed a long-term study in which volunteers had free access to both reduced fat, commercially available products in the laboratory as well as to products obtained from regular shops. We here report the feasibility of such a type of study and the effects of consumption of reduced fat products on blood levels of cholesterol, haemostasis variables, antioxidants and parameters of the immune system. The study was a multicentre parallel comparison trial of six months (so-called MSFAT-study). 241 volunteers received either reduced fat products or full-fat products and the products were clearly labelled as such. Two months before the start of the study, a 1 month adaptation period was executed to optimize the experimental procedures. Food intake was recorded before the start of the adaptation period and 2-4 weeks, 3 months and 6 months after the start of the study. Blood samples were taken before, after 2, 4 and 6 months of the study. In addition, a selection of the reduced fat and full-fat products was sensorically evaluated three times during the study by a subgroup of the volunteers. 220 volunteers completed the study. The reduced fat group consumed on average 46% less fat from the so-called MSFAT-products obtained from the shop at the laboratory than the control group and consumption of these MSFAT-products did not decrease in either of the groups during the time course of the study. The palatability of the reduced fat and full-fat products was similar and as expected, the perceived fattiness of the full-fat products was higher than that of the reduced fat products. No effects were found on blood levels of cholesterol, haemostasis variables, parameters of antioxidant status and immune system characteristics. In conclusion, the experimental manipulation of the fat content of the diet that was achieved and that remained stable throughout the 6 months of the study indicates that this type of set-up is feasible to assess the effects of long-term nutritional intervention in large groups of volunteers under semi-controlled conditions. The regular use of reduced fat products did not positively but also not adversely affect blood cholesterol levels, antioxidant status, haemostasis factors and the body's immune system.

Adult↗

PubMed1996

Effects of dietary fat and carbohydrate exchange on human energy metabolism.

Short-term effects of low-fat (10% fat energy), mixed (30% fat energy), and high-fat (50% fat energy) diets on 24-h energy expenditure, and on its components sleeping metabolic rate, diet induced thermogenesis and energy expenditure for physical activity were studied for 3 days using a respiration chamber in twelve normal-weight female volunteers classified as restrained or unrestrained eaters. There were no significant differences in any of the four measures between the restrained and unrestrained eating subjects on any of the diets. Within the group of restrained eaters, 24-h energy expenditure was significantly decreased during consumption of the mixed diet (8.21 +/- 0.21 MJ/d; p < 0.01) and tended to be decreased on the high-fat diet (8.22 +/- 0.25 MJ/d; p = 0.055), relative to the low-fat diet (8.58 +/- 0.21 MJ/d). Diet composition had no effect on 24-h energy expenditure in the women with unrestrained eating. The results suggest that a low-fat diet would be beneficial in the treatment of obesity, especially if subjects have a restrained type of eating behaviour.

Adult↗

PubMed1996

Long-term effects of consumption of full-fat or reduced-fat products in healthy non-obese volunteers: assessment of energy expenditure and substrate oxidation.

A study was performed to evaluate long-term (6-month) effects of consumption of full-fat products or reduced-fat products on energy and substrate metabolism. Subjects (age, 19 to 35 years; body mass index [BMI], 21 to 28 kg. m-2) were studied during a 36-hour stay in a respiration chamber, before (16 men) and in the third month (16 men) and sixth month (19 men and 17 women) of the study. The diet intervention caused, on average, a change in fat intake of (mean +/- SE) +23 +/- 31 g/d (P < .001) in the full-fat group and of -5 +/- 29 g/d (P .05) in the reduced-fat group. Twenty-four-hour energy expenditure (EE), sleeping metabolic rate (SMR), diet-induced thermogenesis (DIT), and EE for physical activity (ACT) were not different between the groups. Fat oxidation was significantly (P < .05) increased in the full-fat group and was not different from fat intake. During the 6 months of the study, body mass and fat mass were significantly increased in subjects of the full-fat group, whereas there were no changes in body mass or body composition in subjects of the reduced-fat group. It is concluded that in the long run, avoidance of a diet with full-fat products will promote body weight and fast stability.

Adult↗

PubMed1996

Daily variation in energy expenditure during weight-training versus continuous arm cranking and cycling.

To quantify day-to-day variability in energy expenditure (EE) during weight-training, 10 male subjects completed 6 training sessions that consisted of a warming-up and cooling-down phase (10 min; arm cranking or cycling) and a computer-paced weight-training phase using standard weights (42 min; 10 exercises, 3 x 15 repetitions, work to rest ratio = 1:1). The first 2 sessions were used to accommodate. During sessions 3-6 (labelled session A, B, C and D) cardiorespiratory response was continuously measured. Gas-exchange was converted to EE using the Weir formula. In the last two sessions training weights were raised by +/- 50% and the initial warming-up and cooling-down exercise being arm-cranking was replaced by cycling. Mean EE was calculated for last five minutes of the warming-up (WU5) and cooling-down (CD5) and the complete weight-training phase (WT). Mean EE during WT for session A to D was 20.0 +/- 2.7, 19.1 +/- 2.5, 22.2 +/- 2.2 and 21.9 +/- 2.4 kj.min-1, respectively. Daily variation was tested by comparing test-retest phases (A vs B and C vs D). Intra-individual variability in EE during respectively the lower (session A vs B) and higher (session C vs D) weight-training intensity was expressed as: absolute test-retest difference (0.9 +/- 0.5 and 0.7 +/- 0.6 kj.min-1), difference relative to the mean of the test-retest measurements (2.3 +/- 1.4 and 1.6 +/- 1.4%) and as the mean coefficient of variation (3.3 and 2.2%). There were no differences in variability between both WT-intensities nor exercise modes, irrespective of the way variability was expressed. In conclusion, intra-individual variability in EE during weight-training does not differ from variability during arm cranking or cycling.

Adult↗

PubMed1996

Energy expenditure and physical activity in subjects consuming full-or reduced-fat products as part of their normal diet.

It has been suggested that energy expenditure is higher in subjects consuming reduced-fat, high-carbohydrate diets than in subjects consuming full-fat, low-carbohydrate diets. In a 6-month randomized, controlled trial, seventeen women and twenty men (age 20-35 years; BMI 22-28 kg/m2) had free access either to a range of about forty-five reduced-fat products or the full-fat equivalents. At the end of the 6 months, energy intake, sleeping metabolic rate (SMR), average daily metabolic rate (ADMR), and physical activity (AO) were measured. The intervention resulted in a mean difference of the change of the fat content of the diet of 6% of energy (P < 0.01) between the two groups. SMR. ADMR and AO were virtually the same in both groups. The results suggest that the change in fat content of the diet has no effect on physical activity and energy expenditure. However, subjects with a higher activity level consumed more carbohydrate (ADMR/SMR: r = 0.49, P < 0.01: AO: r = 0.57, P < 0.001).

Adult↗

PubMed1996

The influence of physical activity on BMR.

In addition to factors such as fat free mass, hormonal status, genetics and energy balance, previous physical activity has been shown to influence energy turnover during resting (RMR = resting metabolic rate) or basal conditions (BMR = basal metabolic rate). This article presents data on BMR from elite endurance athletes (4 female and 4 male), at least 39 h after their last training session, in comparison with sedentary nonathletic controls matched for sex and fat free mass (FFM). Comparisons with theoretical calculations of BMR were also made. The athletes were shown to have a significantly higher BMR than was expected from calculations based on body mass (16%, P < 0.05) or body composition (12%, P < 0.05). There were no corresponding differences found in the nonathletic control group. The athletes had a 13% higher (P < 0.001) BMR than controls if related to FFM and 16% (P = 0.001) if related to both FFM and fat mass (FM). The athletes were also found to have 10% lower R-values (P < 0.01) indicating higher fat oxidation. The conformity of these findings with the present literature and the possible mechanisms behind them as well as its influence on theoretical calculations of energy turnover (ET) based on activity factors expressed as multiples of RMR are further discussed.

Adult↗

PubMed1996

Heart rate monitoring to assess energy expenditure in children with reduced physical activity.

The aim of the study was to assess whether heart rate (HR) monitoring is suitable to estimate energy expenditure in spastic cerebral palsied (CP) children, who are known to have very low levels of daily physical activity. Total daily energy expenditure (TEE) predicted from HR recording (TEEHR, measured over 2 or 3 d) was therefore compared with TEE measured by doubly labeled water (TEEDLW, measured over 14 d) in nine children with spastic diplegia/tetraplegia (mean +/- SD age 10.7 +/- 1.6 yr). At group level, there was no difference in TEEDLW (7.4 +/- 2.1 MJ.d-1) and TEEHR (7.4 +/- 2.2 MJ.d-1). Spearman correlation between both methods was 0.88 (P < 0.001). Individual estimates of TEEHR ranged from -16.9% to +20.0%, with five TEEHR values within +/- 10% of TEEDLW. It was concluded that also in children with low levels of daily physical activity, HR monitoring (preferably 3 sampling days) can provide a close group estimate of energy expenditure. At the individual level, the method is not suitable.

Adolescent↗

PubMed1996

Body mass index and daily physical activity in anorexia nervosa.

The level of daily physical activity in 11 non-hospitalized women with anorexia (age: 21-48 yr, body mass index (BMI): 12.5-18.3 kg.m-2), compared with 13 normal-weight women (age: 20-35 yr, BMI 19.2-26.7 kg.m-2), was studied in relation to BMI. Daily physical activity over a 7-d period was determined from movement registration and by combining measurements of average daily metabolic rate (measured in a respiration chamber). Group averages of daily physical activity were similar for subjects with anorexia and control subjects. However, women with anorexia had either a low or a high level of daily physical activity, whereas most control subjects had a moderate level of daily physical activity. In the women with anorexia, daily physical activity was significantly related to BMI (r = 0.84). Subjects with a BMI > or = kg.m-2 were equally or more active compared with control subjects, while subjects with a BMI < 17 kg.m-2 were equally or less active compared with control subjects. The increased physical activity at BMI > or = 17 kg.m-2 is considered to be facilitated by an improving physical capacity combined with the advantages of a low body mass during weight-bearing activities. At lower BMI, undereating and declining physical capacity may have caused the observed decrease in daily physical activity.

Adult↗

PubMed1996

Water balance and acute mountain sickness before and after arrival at high altitude of 4,350 m.

The present study is a first attempt to measure water balance and its components at altitude by using labeled water and bromide dilution and relating the results with acute mountain sickness (AMS). Water intake, total water output, and water output in urine and feces were measured over a 4-day interval before and a subsequent 4-day interval after transport to 4,350 m. Total body water and extracellular water were measured at the start and at the end of the two intervals. There was a close relationship between energy intake and water intake, and the relationship was unchanged by the altitude intervention. Subjects developing AMS reduced energy intake and water intake cor respondingly. The increase in total body water (TBW) in subjects developing AMS was accompanied by a reduction in total water loss. They did not show the increased urine output, compensating for the reduced evaporative water loss at altitude. Subjects showed a significant increase in TBW after 4 days at altitude. Subjects with AMS showed the biggest shifts in extracellular water relative to TBW. In conclusion, fluid retention in relation to AMS is independent of a change in water requirements due to altitude exposure. Subjects developing AMS were those showing a fluid shift of at least 1 liter from the intracellular to the extracellular compartment or from the extracellular to the intracellular compartment.

Adult↗

PubMed1996

Daily physical activity assessment: comparison between movement registration and doubly labeled water.

The use of movement registration for daily physical activity assessment was evaluated during a 7-day period in 30 free-living subjects. Body movement was registered with a Tracmor motion sensor consisting of a triaxial accelerometer and a data unit for on-line processing of accelerometer output over 1-min intervals. Average Tracmor output was correlated against four different energy estimates: 1) average daily metabolic rate (ADMR), determined with doubly labeled water; 2) ADMR-sleeping metabolic rate (SMR; determined in a respiration chamber); 3) (ADMR-SMR) per kilogram of body mass; and 4) the overall physical activity level (PAL = ADMR/SMR). The highest correlation was found for the relationship between Tracmor output and PAL (r = 0.58). After correction for Tracmor values arising from vibrations produced by transportation means, this correlation was improved to 0.73. There was no difference between Tracmor output and PAL in discriminating between overall activity levels with "low" (PAL < 1.60), "moderate" (1.60 < or = PAL < or = 1.85), and "high" (PAL > 1.85) intensity. It is concluded that the Tracmor can be used in free-living subjects to distinguish among interindividual as well as intraindividual levels of daily physical activity.

Acceleration↗

PubMed1996

Bromide dilution in adults: optimal equilibration time after oral administration.

Extracellular water is often estimated by bromide dilution. The time interval between oral administration of the dose and blood sampling varies considerably among studies. Because at least two processes are involved during equilibration (distribution of the dose and bromide leaving the body), we performed a bromide-dilution experiment and analyzed the decay data by fitting a biexponential curve. The experiment was carried out in 11 healthy adults (8 women and 3 men, age 21-39 yr). Bromide ingestion (60 mg Br/l estimated total body water) was followed by blood sampling at 2, 3, 4, 6, 10, 25, and 105 (or 170) h. The bromide concentration in serum ultrafiltrate was determined with high-performance liquid chromatography. The bromide concentration in serum after dose intake showed a significant decrease over time. One-exponent functions significantly fitted the data. The two-exponent functions fitted the data significantly better (F-test, P < 0.0001). A model combining the data from all subjects fitted just as well. Equilibration time can be defined as the time at which the first exponential function, which represents distribution of the dose, has decreased to 5% of its starting value. According to this model, the equilibration time of orally administered bromide should be 8.5-11.7 h. This can be achieved by an overnight equilibration.

Administration, Oral↗

PubMed1996

Dietary fat and body fat: an intervention study.

OBJECTIVE: Assessment of body composition in relation to the habitual diet and after a six month dietary intervention. DESIGN: After a baseline measurement subjects were randomly assigned to either a group consuming reduced-fat products or a group consuming full-fat products for six months. SUBJECTS: 108 women and 109 men, equally distributed over the age range 19-35 with BMI between 21 and 28, and the age range 36-55 with BMI between 24 and 30. MEASUREMENTS: Food intake was measured by three day dietary record, body composition by deuterium dilution. RESULTS: At baseline, explained variance of %body fat on age and fat-carbohydrate ratio in the diet together were 17% (P < 0.0001) and 36% (P < 0.0001) for women and men, respectively, and on diet alone 7-8% (P < 0.01) independent of gender. The diet intervention caused on average a change in fat intake and body fat mass in subjects of the reduced-fat group of -5 +/- 29 g/d (P < 0.05) and -0.1 +/- 2.1 kg (ns), respectively, and of +23 +/- 31 g/d (P < 0.0001) and +0.5 +/- 2.3 kg (P < 0.05) in subjects of the full-fat group. The change in the fat content of the diet was positively related to a change in energy intake (fat-carbohydrate ratio: R2 = 0.15, P < 0.0001; g fat: R2 = 0.70, P < 0.0001), the latter explaining 5% of the variation in the change in body fat mass (P < 0.001). Subjects changing the fat content of the diet showed a consequent change in body fat mass only when energy intake changed as well. CONCLUSION: The fat content of the diet has an effect on body fat as a function of the effect of dietary fat on energy intake.

Adipose Tissue↗

PubMed1995

The Maastricht protocol for the measurement of body composition and energy expenditure with labeled water.

An update of practical aspects of the use of labeled water for the measurement of total body water (TBW) and energy expenditure (EE) is presented as applied in Maastricht, The Netherlands. We use a 10-hour equilibration period. The isotopes for the measurement of TBW and EE are routinely administered, after collecting a background urine sample, as a last consumption before the night. Our data show an underestimate of TBW measured with isotope dilution after 4 hours (in the morning), a discrepancy which increases with the size of TBW. No such relation and no significant differences were found after 10-hour (overnight) equilibration. The ratio between the dilution space for deuterium and oxygen-18 is higher than the earlier figure of 1.03, especially in adult subjects with a high body fat content. For an observation period of EE over two weeks, samples from the second and the last voiding on the first, mid, and last day of the observation period are collected. Differences in EE calculated from morning and evening samples within the first and second week allow detection of sampling errors and if so, samples are excluded from the final calculation. Differences of EE between weeks 1 and 2 allow a check for the consistency of the subjects' physical activity level and usually fall within 10% of the average EE over the total observation interval.

Body Composition↗

PubMed1995

Daily physical activity of schoolchildren with spastic diplegia and of healthy control subjects.

OBJECTIVE: To assess the differences in daily physical activity between children with spastic diplegia and healthy schoolchildren, to determine whether special physical activity programs are needed in the population with cerebral palsy. DESIGN: Cross-sectional design. SETTING: Children's rehabilitation center Franciscusoord (day care center) and elementary schools. SUBJECTS: Children with spastic diplegia (5 boys; mean (+/- SD) age 8.0 +/- 1.4 years; 9 ambulant, 1 wheelchair use) and healthy children (5 boys; mean (+/- SD) age 8.4 +/- 1.0 years). MEASUREMENTS: Total daily energy expenditure (TEE) and sleeping metabolic rate (SMR) were measured by the doubly labeled water technique and a respiration chamber. The TEE/SMR ratio was used as an index for the level of daily physical activity. RESULTS: The TEE/SMR ratio under normal daily conditions in the children with cerebral palsy (mean +/- SD): 1.56 +/- 0.19) was significantly lower (p < 0.05) than in their healthy peers (mean +/- SD: 1.83 +/- 0.23) and was similar to the TEE/SMR ratio in a room-sized chamber. CONCLUSION: Children with spastic diplegia are considerably less active than their healthy peers. We recommend special physical activity programs for these children.

Body Height↗

PubMed1995

Energy intake, physical activity and body weight: a simulation model.

In adults, body mass (BM) and its components fat-free mass (FFM) and fat mass (FM) are normally regulated at a constant level. Changes in FM and FFM are dependent on energy intake (EI) and energy expenditure (EE). The body defends itself against an imbalance between EI and EE by adjusting, within limits, the one to the other. When, at a given EI or EE, energy balance cannot be reached, FM and FFM will change, eventually resulting in an energy balance at a new value. A model is described which simulates changes in FM and FFM using EI and physical activity (PA) as input variables. EI can be set at a chosen value or calculated from dietary intake with a database on the net energy of foods. PA can be set at a chosen multiple of basal metabolic rate (BMR) or calculated from the activity budget with a database on the energy cost of activities in multiples of BMR. BMR is calculated from FFM and FM and, if necessary, FFM is calculated from BM, height, sex and age, using empirical equations. The model uses existing knowledge on the adaptation of energy expenditure (EE) to an imbalance between EI and EE, and to resulting changes in FM and FFM. Mobilization and storage of energy as FM and FFM are functions of the relative size of the deficit (EI/EE) and of the body composition. The model was validated with three recent studies measuring EE at a fixed EI during an interval with energy restriction, overfeeding and exercise training respectively. Discrepancies between observed and simulated changes in energy stores were within the measurement precision of EI, EE and body composition. Thus the consequences of a change in dietary intake or a change in physical activity on body weight and body composition can be simulated.

Adult↗

PubMed1995

Energy expenditure, physical activity and basal metabolic rate of elderly subjects.

Energy expenditure, and therefore energy requirement, generally decreases with advancing age because of a decrease in basal metabolic rate (BMR) and physical activity. The aim of the present study was to measure total energy expenditure (EE) and activity level in a group of healthy elderly (sixteen men aged 71.3 (SD 4.9) years; ten women aged 67.6 (SD 4.1) years) and young adults (nineteen men aged 30.4 (SD 5.0) years; ten women aged 27.2 (SD 3.9) years) by using the doubly-labelled water method in combination with measurements of BMR. Age-related differences in body composition and their relationship to BMR and activity level were studied. EE was lower in elderly compared with young adults, partly due to a significantly lower BMR. The lower BMR was not fully explained by the lower fat-free mass (FFM) in the elderly. Energy expended (MJ/d) on activity was higher for the younger subjects although there was no significant difference in the physical activity index (PAI = EE/BMR) between the two age groups. The effect of physical activity level is twofold: first it has a positive effect on the BMR, and second it has a positive effect on the FFM. Both effects involve an increase in the total EE with an increased level of physical activity. At energy balance this will lead to increased energy and nutrient intake, making especially the elderly less vulnerable to inadequate energy and nutrient intake.

Activities of Daily Living↗

PubMed1995

Physical activity, body composition and bone density in ballet dancers.

The main purpose of the present study was to examine factors that affect bone mineral density (BMD) in female ballet dancers. Training history, Ca intake, body composition, total body BMD (TBMD) and site-specific BMD, and bone mineral content were described in twenty-four female ballet dancers (mean age 22.6 (SD 4.5) years). Training history was determined by questionnaires, Ca intake by 7 d dietary record, BMD and bone mineral content by dual-energy X-ray absorptiometry (DXA), total body water by 2H dilution, extracellular water by bromide dilution, body fat by underwater weighing (UWW; two-component model), DXA, and the four-component (4C) model. Dancers had a significantly lower body mass index (BMI 18.9 (SD 1.0) kg/m2) than controls (21.3 (SD 1.9) kg/m2), with significantly lower percentage body fat (17.4 (SD 3.9) v. 24.4 (SD 5.1)) but comparable fat-free mass. Mean TBMD (1.147 (SD 0.069) g/cm2) was significantly higher (6%) compared with that of a reference population. These high values could be attributed to the high BMD of legs and pelvis, the weight-bearing sites of the dancer's body. No relationship was found between age, start of ballet classes, period (years) of dancing, Ca intake, and BMD (total and site-specific). However, TBMD was positively related to BMI, and negatively related to the age of menarche. BMD of the legs was significantly related to BMI, and negatively related to the age of menarche. BMD of the legs was significantly related to daily period (h) of training. Depending on the method used the percentage body fat ranged from 16.4 (by DXA) to 18.3 by the 4C model. These differences were significantly related to the TBMD. Percentage body fat by the different methods was not significantly different, except for DXA and 4C model. The present study showed that, despite the factors that have a negative effect on BMD, such as low body mass and late menarche, BMD in female ballet dancers was relatively high. These high values were probably caused by high levels of weight-bearing physical activity.

Absorptiometry, Photon↗

PubMed1995

Whole-body protein turnover in elderly men and women: responses to two protein intakes.

In this study the effect of protein intake (12% and 21% of total energy intake, diets A and B, respectively) on nitrogen balance and on whole-body protein turnover (PT) was measured in 17 elderly men and 11 elderly women (mean +/- SD: 74 +/- 12 y and 68 +/- 9 y, respectively) with different levels of physical activity. Mean (+/- SD) nitrogen balance (diet A: -0.004 +/- 0.027 g.kg-1.d-1, diet B: 0.011 +/- 0.064 g.kg-1.d-1) did not differ significantly from zero during either diet. PT increased significantly when the protein content of the diet increased from 12% to 21% of total energy (P < 0.0001). There was a positive correlation between protein intake and PT (diet A: synthesis and breakdown, P < 0.01; diet B: synthesis, P < 0.001; breakdown, P < 0.0001). PT rates were significantly higher for men when compared with women, even when corrections were made for differences in body composition (P < 0.05).

Aged↗