Self-administered questionnaire compared with interview to assess past-year physical activity.

PURPOSE: The Modifiable Activity Questionnaire (MAQ) is a physical activity questionnaire shown to be both valid and reliable and was initially designed to be interviewer-administered. After translation and adaptation into French, the objective of the study was to compare past-year physical activity data obtained by self-administration of this questionnaire and by interviewer-administration. METHODS: 84 subjects (22 men, 62 women, age 36-63 yr) enrolled in an ongoing prospective study in France (the SUpplementation en VItamines et Minéraux AntioXydants or SU.VI.MAX study) completed both versions of the questionnaire in a randomized order with a mean (SD) delay of 7.9 (5.8) d between the two modes. Past-year leisure and occupational physical activity were expressed as both h x wk(-1) and MET-h x wk(-1) of activity, and television watching was expressed as h x d(-1). Analysis of variance on ranks was used to compare activity variables obtained by self-administration and interview. Agreement was assessed by nonparametric intraclass correlation coefficients. RESULTS: A significant effect of the mode of administration was found only for past-year leisure physical activity with lower values reported in self-administered conditions compared with interview. However, a high level of concordance between the two modes of administration was observed for all variables as shown by the intraclass correlation coefficients: 0.90 for leisure physical activity (h x wk(-1)), 0.82 for occupational activity (h x wk(-1)), 0.83 for total (leisure and occupational combined) physical activity (h x wk(-1)), and 0.97 for television viewing (h x d(-1)). CONCLUSIONS: The agreement between the two modes of administration of the questionnaire suggests that the self-administered version of the MAQ is a valuable tool to assess past-year physical activity and inactivity in self-administered conditions. This instrument could be used in large-scale population studies investigating the relationships between physical activity and health outcomes.

Maternal diabetes status does not influence energy expenditure or physical activity in 5-year-old Pima Indian children.

Children of women who have diabetes during pregnancy are more likely to become obese by early adulthood than those of women with normal glucose tolerance during pregnancy. Obesity can result from either excess food intake, low levels of energy expenditure or both. In our study, we tested whether maternal diabetes status influences total energy expenditure (TEE by doubly labelled water), resting metabolic rate (RMR by ventilated hood) and physical activity level (PAL = TEE/RMR and assessed by activity questionnaire). Measurements were taken in 88 5-year-old Pima Indian children, 24 children of women with diabetes (2-h plasma glucose > or = 11.1 mmol/l) diagnosed before or during pregnancy and 64 children of women with normal glucose tolerance (2-h plasma glucose < 7.8 mmol/l during pregnancy and no prior history of abnormal glucose tolerance). Although birth weight was higher in children of diabetic than of nondiabetic women (mean +/- SD; 3.8 +/- 0.6 vs 3.5 +/- 0.4 kg, p < 0.03), there were no differences in weight (26.4 +/- 6.9 vs 24.2 +/- 5.6 kg) or per cent body fat (18O dilution; 33 +/- 8 vs 31 +/- 8%) between the groups at 5 years of age. There was no difference in TEE (6508 +/- 1109 vs 6175 +/- 942 kJ/d) or in RMR (4674 +/- 786 vs 4483 +/- 603 kJ/d) expressed as absolute values or after adjustment for weight and sex (TEE) or fat-free mass, fat mass, and sex (RMR). Physical activity level was also similar between the groups (1.40 +/- 0.12 vs 1.38 +/- 0.12). These results suggest that maternal diabetes status does not influence energy expenditure in the children by 5 years of age. Thus the greater obesity seen at older ages in the children of women with diabetes could be due to excess energy intake. Alternatively, if energy expenditure does have a role in the aetiology of obesity in these children, perhaps it does so only in older children.

Low levels of physical activity in 5-year-old children.

As the prevalence of obesity in Western societies has increased to disturbing levels, interest in the role of physical inactivity in promoting this trend has increased. We assessed physical activity energy expenditure (AEE) in 127 5-year-old children, 43 of whom were white children and 84 Pima Indian children; the latter group represents a population with an extremely high prevalence of obesity. Total energy expenditure (TEE) and resting metabolic rate (RMR) were measured by the doubly labeled water method and indirect calorimetry, respectively. From these measured values, different indexes of physical activity were calculated, including AEE = TEE-(RMR + 0.1 x TEE) and physical activity level (PAL = TEE/RMR). By the age of 5 years, Pima Indian children were significantly heavier (23.0 +/- 5.3 kg vs 19.1 +/- 2.6 kg) and fatter (30 +/- 7% vs 21 +/- 5% body fat) than white children (p < 0.0001), whereas TEE (5996 +/- 1005 kJ/day vs 5690 +/- 760 kJ/day) and RMR (4431 +/- 625 kJ/day vs 4236 +/- 534 kJ/day) were similar in the 2 groups in both absolute values and after adjustment for fat-free mass, fat mass, and sex. Both white and Pima Indian children had physical activity levels 20% to 30% lower (PAL = 1.35 +/- 0.13) than currently recommended by the World Health Organization (1.7 to 2.0). However, the different calculated indexes of physical activity were comparable in the two racial groups. Differences in TEE or AEE are unlikely to explain the obesity seen in Pima Indian children at a later age, suggesting that excess food intake is likely to play a major role in the cause of obesity in this obesity-prone population. However, both white and Pima Indian children have surprisingly low levels of physical activity, a condition that portends poorly for the prevention of obesity in adulthood.

Physical activity and body composition in 10 year old French children: linkages with nutritional intake?

OBJECTIVES: To investigate the relationships between physical activity, dietary intake and body composition in children. DESIGN: A cross-sectional study on physical activity, nutritional intakes and body composition conducted in 86 healthy 10 y old French children. In addition, growth parameters and nutritional intakes were available from the age of 10 months. MEASUREMENTS: Physical activity level (using a validated activity questionnaire over the past year), nutritional intake (dietary history method), anthropometric measurements (body weight, height, arm circumference, triceps and subscapular skinfolds, Body Mass Index (BMI), arm muscle and arm fat areas calculated from these measurements) at the age of 10 y. Anthropometric measurements and nutritional intakes were recorded in the same children at the age of 10 months and every 2 y from the age of 2 y. RESULTS: At the age of 10 y, active children ingested significantly more energy than less active children, mostly due to higher energy intake at breakfast and in the afternoon. This higher energy intake was accounted for by increased consumption of carbohydrates (281 g vs 246 g; 49.6% vs 47.4% of total energy). Even if the amounts of fat consumed were similar in both groups (90 g vs 84 g; P = 0.09), the percentage of fat intake was lower in active children (35.4% vs 37.4%; P = 0.04). The percentage of protein was not different (14.9% vs 15.3%; P = 0.33). In spite of a higher energy intake in the active group, active and less active children had similar BMI at the age of 10 y. However, their body composition differed significantly: active children had a higher proportion of fat-free mass, a lower proportion of fat-mass as measured in the arm and they had a later adiposity rebound. Fatness was significantly and positively associated with the time spent watching television and video games. CONCLUSIONS: Physical activity was associated with improved body composition and growth pattern. This association may be related to nutritional changes: active children consumed more energy by increasing carbohydrate, thus reducing the relative fat content of their diet. These results provide support to encourage physical activity during childhood.

Racial difference in body core temperature between Pima Indian and Caucasian men.

A low body temperature is associated with a low metabolic rate for a given body size and body composition. These two traits might have been assets in the history of a population subjected to cycles of feast and famine, but became part of an obesity-prone syndrome in our westernized society characterized by plenty of food and a sedentary lifestyle. We tested whether Pima Indians have lower body temperatures than Caucasians, a trait which might partly explain the high prevalence of obesity in this population. Twenty-five Pima Indian (28 +/- 6 yrs, 87.8 +/- 22.8 kg, 29 +/- 9% body fat) and 25 Caucasian (30 +/- 5 yrs, 80.7 +/- 18.4 kg, 22 +/- 11% body fat) men had body core temperatures measured by telemetry for 24 h while in a respiratory chamber. Mean daily body core temperature was 36.93 +/- 0.12 and 36.90 +/- 0.22 degrees C in Pima Indians and Caucasians, respectively. Since body core temperature during sleep (SLBCT) correlated with percentage body fat, a subset of 10 Pima Indians and 10 Caucasians were pair-matched for body weight and percentage body fat. In this group, SLBCT was lower in Pima Indians than in Caucasians (36.45 +/- 0.10 vs 36.65 +/- 0.27 degrees C; P < 0.01) and, ethnic group accounted for 20% of the variance in SLBCT (P < 0.01). Surprisingly, the lower SLBCT was not associated with a low metabolic rate and therefore does not seem to play a role in the etiology of obesity in Pima Indians.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between sleep stages and metabolic rate in humans.

Differences in sleeping metabolic rate (SMR) among subjects may be related to different levels of energy expenditure associated with sleep stages. The relationship between energy expenditure and sleep stages was investigated overnight in 29 subjects (14 Caucasians and 15 Pima Indians, 18 males and 11 females; mean +/- SD, 31 +/- 7 yr, 83 +/- 26 kg, 27 +/- 11% fat). Sleep stages were determined by electroencephalogram recording, whereas energy expenditure was measured in a 1,000-liter Plexiglas sleep box constructed around a bed as a fast-response open-circuit indirect calorimeter. Eighty-five percent of the interindividual variability in SMR was explained by differences in fat-free mass, fat mass, age, sex, and race (r2 = 0.85). The intra-individual variance in SMR over time was related to sleep stages and to clock time. Within subjects, SMR in stage 3 was significantly lower than in stage 2 (-39 +/- 18 kcal/day; P < 0.05) and rapid eye movement sleep (-51 +/- 23 kcal/day; P < 0.05). Also, sleep stages were associated with different respiratory quotients. Because sleep stages are associated with only small differences in energy metabolism, our results suggest that sleep stages play a minor role in the variance of SMR among subjects. However, the duration of sleep may contribute to the variability of 24-h energy expenditure.

Energy cost of arousal: effect of sex, race and obesity.

The basal (BMR) to sleeping metabolic rate (SMR) ratio might represent an estimate of the activation of the nervous system (central/sympathetic) from sleeping to basal state. Since this activation might be influenced by the degree of obesity, and might be different between sexes, we retrospectively analysed energy expenditure data collected for a large number of subjects. Twenty-four hour energy expenditure (24EE), BMR and SMR were measured in a respiratory chamber in 122 Caucasians (63 males/59 females, 32 +/- 10 years, 94 +/- 33 kg, 29 +/- 11% fat) (means +/- s.d.) and in 123 Pima Indians (68 males/55 females, 29 +/- 7 years, 100 +/- 25 kg, 34 +/- 9% fat). The BMR/SMR ratio varied greatly between individuals (1.05 +/- 0.08; range 0.87-1.34). In Pima Indians, BMR/SMR was inversely correlated to both fat mass (r = -0.26; P < 0.01) and BMI (r = -0.22; P < 0.05), whereas, in Caucasians, BMR/SMR was inversely correlated to waist/thigh circumference ratio (r = -0.28; P < 0.01). On average, the BMR/SMR was higher in Pima Indians than in Caucasians (1.06 +/- 0.08 vs. 1.03 +/- 0.07, P < 0.01) and higher in Pima Indian males than in Pima Indian females (1.08 +/- 0.09 vs. 1.04 +/- 0.06, P < 0.05). Studies are needed to investigate whether these differences in the increase in energy expenditure from the sleeping to the basal state are related to differences in the activation of the nervous system and/or to other metabolic factors.

Estimating body composition of young children by using bioelectrical resistance.

It is currently unclear whether age-specific equations should be used for assessing body composition from bioelectrical resistance. Kushner et al. (Am. J. Clin. Nutr. 56: 835-839, 1992) showed that the relationship between height2/resistance and total body water (TBW) is robust across a wide age range, although uncertainty remained over the relationship in preschool children. We therefore cross-validated the Kushner equation for predicting total body water in 4- to 6-yr-old children in two independent laboratories. TBW was measured from H2 18O dilution, and bioelectrical resistance and reactance were measured using an RJL 101A analyzer in 31 children (15 females, 16 males; 5 +/- 0.8 yr) studied in Burlington, Vermont, and 30 children (14 females, 16 males; 5 +/- 0.2 yr) studied in Phoenix, Arizona. There was no significant difference between TBW predicted from the Kushner equation and that measured in children in Burlington (11.76 +/- 2.00 vs. 11.91 +/- 2.46 kg; r = 0.94) or in Phoenix (11.53 +/- 1.64 vs. 11.66 +/- 1.90 kg; r = 0.94). The Kushner equation for TBW can be transformed into an equation for fat-free mass (FFM) by using published age- and gender-specific constants for the hydration of FFM: hydration of FFM = 76.9 - 0.25 age (yr) - 1.9 gender where female equals 0 and male equals 1. The intraclass reliability for estimates of fat mass and FFM with the use of bioelectrical resistance in an independent group of 26 children (5.0 +/- 0.8 yr, 20.2 +/- 3.0 kg) was > 0.99 for duplicate observations performed 2 wk apart.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced sympathetic nervous activity. A potential mechanism predisposing to body weight gain.

The sympathetic nervous system is recognized to play a role in the etiology of animal and possibly human obesity through its impact on energy expenditure and/or food intake. We, therefore, measured fasting muscle sympathetic nerve activity (MSNA) in the peroneal nerve and its relationship with energy expenditure and body composition in 25 relatively lean Pima Indian males (means +/- SD; 26 +/- 6 yr, 82 +/- 19 kg, 28 +/- 10% body fat) and 19 Caucasian males (29 +/- 5 yr, 81 +/- 13 kg, 24 +/- 9% body fat). 24-h energy expenditure, sleeping metabolic rate, and resting metabolic rate were measured in a respiratory chamber, whereas body composition was estimated by hydrodensitometry. Pima Indians had lower MSNA than Caucasians (23 +/- 6 vs 33 +/- 10 bursts/min, P = 0.0007). MSNA was significantly related to percent body fat in Caucasians (r = 0.55, P = 0.01) but not in Pimas. MSNA also correlated with energy expenditure adjusted for fat-free mass, fat mass, and age in Caucasians (r = 0.51, P = 0.03; r = 0.54, P = 0.02; and r = 0.53, P = 0.02 for adjusted 24-h energy expenditure, sleeping metabolic rate, and resting metabolic rate, respectively) but not in Pima Indians. In conclusion, the activity of the sympathetic nervous system is a determinant of energy expenditure in Caucasians. Individuals with low resting MSNA may be at risk for body weight gain resulting from a lower metabolic rate. A low resting MSNA and the lack of impact of MSNA on metabolic rate might play a role in the etiology of obesity in Pima Indians.

Decreased physical activity in Pima Indian compared with Caucasian children.

Since reduced physical activity might be a risk factor for body weight gain, we studied the relationship between physical activity and body composition in 43 Pima Indian children (22 male/21 female, mean +/- s.d.: 9.9 +/- 1.1 years) and 42 Caucasian children (21 male/21 female, 9.7 +/- 1.2 years). A list of usual sport leisure activities was established (e.g. bicycling, swimming, basketball) and the subjects were asked how much time they had devoted to each activity over the past week and the last year. Data on time spent playing outside (excluding sport leisure activities for the estimation of physical activity) and watching television/videos were also collected. Pima Indians were taller (143 +/- 9 vs. 137 +/- 8 cm, P < 0.001), heavier (48.6 +/- 15.8 vs. 32.9 +/- 7.8 kg, P < 0.0001) and fatter (39 +/- 16 vs. 24 +/- 7% fat, P < 0.001) than Caucasians. Pima Indian girls showed significantly lower past year and past week sport leisure activity than Caucasian girls (P < 0.01) and spent significantly more time watching television/videos (P < 0.05). Pima boys also showed significantly lower past week sport leisure activity than Caucasian boys (P < 0.05). In Pima Indian boys, past year sport leisure activity correlated negatively (P < 0.05) with body mass index (r = -0.49) and percentage body fat (r = -0.56). However, such correlations were not found in Pima Indian girls, possibly due their very low levels of activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Daily energy expenditure by five-year-old children, measured by doubly labeled water.

Current recommendations for daily energy requirements in 5-year-old children (90 kcal/kg per day) are based on energy intake associated with normal growth. It is not known, however, how these recommendations compare with total free-living energy expenditure (TEE) and how much of TEE is related to physical activity. The TEE and the resting metabolic rate (RMR) were measured in 28 white children, aged 5 years (15 boys, 13 girls; mean (+/- SD) weight 20.1 +/- 3.4 kg; height 113 +/- 6 cm; fat 20% +/- 5%). The TEE was calculated during a 7-day period from urinary elimination rates of deuterium (2H) and heavy oxygen (18O) by using a modification of the two-point slope-intercept method; RMR was measured by a ventilated-hood indirect calorimeter. Physical activity indexes were also collected from questionnaires completed by the parents. Measured TEE was considerably lower than the recommended dietary allowances (1370 +/- 222 kcal/day vs 1807 +/- 310 kcal/day; p < 0.0001), whereas measured RMR was slightly higher than predicted RMR (1001 +/- 119 kcal/day vs 952 +/- 78 kcal/day; p < 0.001). The energy cost of physical activity accounted for only 16% +/- 7% of TEE. An index of activity, assessed as the difference between the measured TEE and the predicted TEE, correlated positively with past-year sport-leisure activity assessed by questionnaire (r = 0.40; p < 0.05). We conclude that measured TEE in 5-year-old children yields lower values (approximately 400 kcal/day) than current estimates. A minute part of this difference (20 to 30 kcal/day) is related to the changes in energy stores during growth, but most seems due to lower-than-expected levels of physical activity. This might be related to increased television viewing, which replaces activities requiring energy.

Effects of chronic dietary fructose with and without copper supplementation on glycaemic control, adiposity, insulin binding to adipocytes and glomerular basement membrane thickness in normal rats.

Sucrose feeding over a long period has been reported to induce glomerular basement membrane (GBM) thickening and insulin resistance in normal rats. These effects are attributed to the fructose moiety of the sucrose molecule, to Cu deprivation or both. Consequently, our aim was to evaluate the long-term effects of fructose feeding with normal or high amounts of Cu on body weight, plasma lipids, blood glucose regulation, GBM thickening and insulin binding to adipocytes. Four groups of eight Sprague-Dawley rats were fed for 10 weeks on a diet containing 570 g carbohydrate/kg supplied either as starch (S), dextrose (D), fructose (F) or fructose-starch (1:1, w/w; FS), and an adequate amount of Cu (12 micrograms Cu/g diet). A fifth group was fed on diet F supplemented with 24 micrograms Cu/g diet (FCu). After 10 weeks the epididymal adipose tissue and kidney weights expressed per 100 g body weight (relative weight) were heaviest in the F and FCu groups (P < 0.0001, ANOVA). The GBM thickness was within the normal range in the five groups but significantly higher in group D (1.95 (SE 0.04) nm and lower in group FS (1.79 (SE 0.02) nm when compared with group S (1.85 (SE 0.03) nm; P < 0.05). Insulin binding to adipocytes (expressed per cell) was lowest in the F and FCu groups, intermediate in groups D and FS and highest in group S (P < 0.05). Fasting plasma insulin level was higher in group F than in the FCu and FS groups (P < 0.05), whereas fasting plasma glucose, total cholesterol and triacylglycerol levels remained within the normal range in all groups. We conclude that in normal rats a 10-week fructose-rich diet with an adequate amount of Cu produced deleterious metabolic effects on adipose tissue, insulin binding to adipocytes, and plasma insulin, but not on GBM thickening even though kidney weight was significantly increased. However, a moderate fructose intake mixed with other sugars did not have adverse effects.

Relationship between skeletal muscle lipoprotein lipase activity and 24-hour macronutrient oxidation.

A low ratio of whole-body 24-h fat/carbohydrate (CHO) oxidation has been shown to be a predictor of subsequent body weight gain. We tested the hypothesis that the variability of this ratio may be related to differences in skeletal muscle metabolism. Since lipoprotein lipase (LPL) plays a pivotal role in partitioning lipoprotein-borne triglycerides to adipose (storage) and skeletal muscle (mostly oxidation), we postulated that a low ratio of fat/CHO oxidation was associated with a low skeletal muscle LPL (SMLPL) activity. As an index of substrate oxidation, 24-h RQ was measured under sedentary and eucaloric conditions in 16 healthy nondiabetic Pima males. During a 6-h euglycemic, hyperinsulinemic clamp, muscle biopsies were obtained at baseline, 3, and 6 h. Heparin-elutable SMLPL activity was 2.92 +/- 0.56 nmol free fatty acids/g.min (mean +/- SD) at baseline, was unchanged (2.91 +/- 0.51) at the third hour, and increased significantly (P < 0.05) to 3.13 +/- 0.57 at the sixth hour of the clamp. The mean (of baseline and 3-h) SMLPL activity correlated inversely with 24-h RQ (r = 0.57, P < 0.03) but not with body size, body composition, or insulin-mediated glucose uptake. Since SMLPL activity is related to the ratio of whole body fat/CHO oxidation rate, a decreased muscle LPL activity may, therefore, predispose to obesity.

Effect of phenylpropanolamine on energy expenditure and weight loss in overweight women.

The effect of phenylpropanolamine (PPA), a noncatecholamine sympathomimetic weight-loss agent, on energy expenditure (EE) and substrate oxidation was measured in a respiratory chamber in 24 overweight women after 4 d of treatment (PPA or placebo) during weight maintenance and after 7 wk of treatment on a hypoenergetic diet (70% of measured baseline 24-h EE). Twelve women (37 +/- 2 y, 74 +/- 6 kg, 33 +/- 1% body fat) were randomly assigned to the PPA group [75 mg osmotic release oral system (OROS)-PPA/d] and 12 (mean +/- SEM: 38 +/- 2 y, 79 +/- 1 kg, 37 +/- 1% body fat) to the placebo group. Baseline measurements of 24-h EE (7849 +/- 226 vs 7834 +/- 142 kJ/d), basal metabolic rate (BMR) and 24-h respiratory quotient (RQ) were comparable between PPA and placebo groups. After 4 d of treatment, there was no significant effect of PPA on 24-h EE, BMR, and 24-h RQ compared with placebo. Over the 7-wk diet period, however, the PPA group (n = 8) had greater weight loss than the placebo group (n = 10): -5.0 +/- 0.5 vs -3.0 +/- 0.4 kg (P < 0.05). The changes in 24-h EE and 24-h RQ over the 7 wk were not different between the groups. We conclude that weight loss is enhanced by OROS-PPA, but this change was not explained by changes in 24-h EE or 24-h RQ. The small number of subjects may have hindered detection of subtle differences in energy metabolism.

Metabolic rate and body composition of Pima Indian and Caucasian children.

A low metabolic rate for a given body size and body composition may be a risk factor for body weight gain. Because the prevalence of obesity exceeds 75% in the Pima Indian population, we investigated whether Pima Indian children have a low resting metabolic rate (RMR) when compared with Caucasian children. Body composition (bioelectrical resistance) and RMR were measured in 43 Pima Indian children (22 male/21 female, means +/- SD = 9.9 +/- 1.1 year) and 42 Caucasian children (21 male/21 female, 9.7 +/- 1.2 year). Pima Indian children were taller (p < 0.001), heavier (p < 0.001), and fatter (p < 0.0001) than Caucasian children. Absolute values of RMR were higher in the Pimas than in the Caucasians (p < 0.001), but were similar when adjusted for differences in body size, body composition, and sex. In Pima Indian girls before puberty (< 10 years; n = 8), adjusted values of RMR were negatively correlated with the mean body mass index (BMI) of the parents (r = -0.88; p < 0.005). Inasmuch as resting metabolic rate was not low in Pima children, the data suggest that the major factors in the weight gain of 10-year-old Pima children may be reduced physical activity and/or excess energy intake. However, this study does not exclude the possibility that a low metabolic rate may be a predisposing factor at an earlier age.

Lower sedentary metabolic rate in women compared with men.

Since females have a greater prevalence of obesity compared with males, the question arises whether females have lower metabolic rate than males after adjusting for differences in body weight and composition. 24-h energy expenditure (24EE), basal metabolic rate (BMR), and sleeping metabolic rate (SMR) were measured in a respiratory chamber in 235 healthy, nondiabetic Caucasian subjects (114 males, 121 females). Body composition was determined by hydrodensitometry. 24EE was 124 +/- 38 kcal/d (P less than 0.002) higher in males than females after adjusting for differences in fat-free mass, fat mass, and age. Spontaneous physical activity was not significantly different between males and females. Since adjusted 24EE was 106 +/- 39 kcal/d (P less than 0.01) higher in females during the luteal phase of the menstrual cycle compared with females during the follicular phase, energy expenditure was analyzed in a subset (greater than 50 yr) to minimize the confounding effect of menstrual status. 24EE (160 +/- 66 kcal/d; P less than 0.03), BMR (116 +/- 45; P less than 0.02), and SMR (208 +/- 68 kcal/d; P less than 0.005) were higher in males compared with females of the older subset after adjusting for differences in body composition, age, and activity. In summary, sedentary 24EE is approximately 5-10% lower in females compared with males after adjusting for differences in body composition, age, and activity.

Resting metabolic rate and body composition of Pima Indian and Caucasian children.

Since a low metabolic rate (for a given body size and body composition) is a risk factor for body weight gain and obesity is prevalent among Pima Indians, we have tested whether Pima Indian children have a low resting metabolic rate (RMR) as compared to Caucasian children. Body composition (bioelectrical resistance) and RMR were measured in 43 Pima Indian children (22 male/21 female, mean +/- s.d. 9.9 +/- 1.1 years) and 42 Caucasian children (21 male/21 female, 9.7 +/- 1.2 years). Pima children were taller (143 +/- 9 vs. 137 +/- 8 cm, P less than 0.001), heavier (48.6 +/- 15.8 vs. 32.9 +/- 7.8 kg, P less than 0.001) and fatter (39 +/- 10 vs. 24 +/- 7% fat, P less than 0.001) than Caucasians. Absolute values of RMR were higher in Pimas than in Caucasians (6234 +/- 1201 vs. 5171 +/- 715 kJ/day, P less than 0.001), but similar when adjusted for differences in body size, body composition and sex. Contrary to our hypothesis, we did not find a decreased RMR in Pima children when compared to Caucasian children. Therefore, the high prevalence of obesity in Pima children at age 10 suggests that excess energy intake and/or low levels of physical activity might be the major aetiological factor. However, this study does not exclude the possibility that a low metabolic rate might be a predisposing factor at an earlier age.

Twenty-four-hour energy expenditure in Pima Indians with type 2 (non-insulin-dependent) diabetes mellitus.

To assess the impact of Type 2 (non-insulin-dependent) diabetes mellitus on energy metabolism, 24-h energy expenditure, basal metabolic rate and sleeping metabolic rate were measured in a respiratory chamber in 151 Pima Indians, 102 with normal glucose tolerance (67 male/35 female, (mean +/- SD) 28 +/- 7 years, 99 +/- 24 kg, 32 +/- 9% body fat) and in 49 with Type 2 diabetes (22 male/27 female, 35 +/- 11 years, 107 +/- 33 kg, 39 +/- 7% body fat), after at least 3 days on a weight maintaining diet. After adjustment for differences in fat-free mass, fat mass, age and sex, 24-h energy expenditure, basal metabolic rate and sleeping metabolic rate were significantly higher in diabetic patients than in control subjects (72 kcal/day, p less than 0.05; 99 kcal/day, p less than 0.005; 99 kcal/day, p less than 0.001 respectively). Spontaneous physical activity was similar in both groups whereas the thermic effect of food, calculated as the mean energy expenditure corrected for activity throughout the day above sleeping metabolic rate and expressed as a percentage of energy intake, was significantly lower in Type 2 diabetic patients (17.1 +/- 7.1 vs 19.8 +/- 5.6%, p less than 0.05). Adjusted values of 24-h energy expenditure, basal metabolic rate and sleeping metabolic rate were correlated with hepatic endogenous glucose production (r = 0.22, p less than 0.05; r = 0.22, p less than 0.05; r = 0.31, p less than 0.01 respectively). Therefore, increased basal and sleeping metabolic rates, resulting in increased 24-h sedentary energy expenditure may play a role in the weight loss so often observed in Type 2 diabetic subjects in addition to the energy loss from glycosuria.

The use of low glycaemic index foods improves metabolic control of diabetic patients over five weeks.

The aim of the present study was to determine whether any benefit might occur from lowering the glycaemic index of diet in the medium term in diabetic patients. Eighteen well-controlled diabetic patients (12 Type 1 and 6 Type 2 non-insulin-treated), were assigned to either a high mean glycaemic index or low mean glycaemic index diet for 5 weeks each in a random order using a cross-over design. The two diets were equivalent in terms of nutrient content and total and soluble fibre content. The glycaemic indices were 64 +/- 2 (mean +/- SD) % and 38 +/- 5% for the two diets. The high glycaemic index diet was enriched in bread and potato and the low glycaemic index diet in pasta, rice, and legumes. At the end of the study periods, the following variables were improved on the low compared to the high glycaemic index diet: fructosamine (3.9 +/- 0.9 vs 3.4 +/- 0.4 mmol l-1, p less than 0.05); fasting blood glucose (10.8 +/- 2.8 vs 9.6 +/- 2.7 mmol l-1, p less than 0.02); 2-h postprandial blood glucose (11.6 +/- 2.9 vs 10.3 +/- 2.5 mmol l-1, p less than 0.02); mean daily blood glucose (12.0 +/- 2.5 vs 10.4 +/- 2.7 mmol l-1, p less than 0.02); serum triglycerides (1.5 +/- 0.9 vs 1.2 +/- 0.6 mmol l-1, p less than 0.05). No significant differences were found in body weight, HbA1C, insulin binding to erythrocytes, insulin and drug requirements, and other circulating lipids (cholesterol, HDL-cholesterol, phospholipids, Apolipoprotein A1, Apolipoprotein B). Thus the inclusion of low glycaemic index foods in the diet of diabetic patients may be an additional measure which slightly but favourably influences carbohydrate and lipid metabolism, requires only small changes in nutritional habits and has no known deleterious effects.