Energy intake and physical activity in Pima Indians: comparison with energy expenditure measured by doubly-labeled water

To test the validity of survey techniques for measuring diet and activity patterns of Pima Indians, sequential 24-hour recalls, a food frequency questionnaire (FFQ), and an activity questionnaire were compared to free-living energy expenditure. Total energy expenditure (TEE) measured by doubly labeled water was 13.27 +/- 2.95 MJ/d for the 12 males (mean +/- SD: 35 +/- 14 yr; 97 +/- 35 kg; 32 +/- 9% body fat) and 11.67 +/- 1.85 MJ/d for the 9 females (31 +/- 13 yr; 106 +/- 32 kg; 49 +/- 6% body fat). Energy intake assessed by 24-hour recall was 13.59 +/- 7.81 MJ/d for men and 9.29 +/- 2.77 MJ/d for women, compared to 12.84 + 2.85 and 9.40 + 2.61 MJ/d for men and women, respectively, by FFQ. Both dietary methods indicated significant underreporting by women when compared to TEE. Energy intake assessed by FFQ was significantly correlated with TEE (r=0.48, p=0.03). This was true with 24-hour recall energy intake only when data from two extremely large alcohol consumers were eliminated (r=0.64, p=0.03, N=19). Although a low level of activity was apparent, the activity questionnaire produced significant correlations with measurements of energy expenditure and therefore represents an important tool for examining the relationship between physical activity and diseases.

Body weight gain in free-living Pima Indians: effect of energy intake vs expenditure

BACKGROUND

Obesity results from a chronic imbalance between energy intake and energy expenditure. However, experimental evidence of the relative contribution of interindividual differences in energy intake and expenditure (resting or due to physical activity) to weight gain is limited.

OBJECTIVE

To assess prospectively the association between baseline measurements of daily energy metabolism and weight changes by studying free-living adult Pima Indians, one of the most obese populations in the world.

DESIGN

A study of the pathogenesis of obesity in the Pima Indians living in Southwestern Arizona. The participants were 92 nondiabetic Pima Indians (64M/28F, 35+/-12 y, 35+/-9% body fat; mean+/-s.d.). At baseline, free-living daily energy metabolism was assessed by doubly labeled water and resting metabolic rate (RMR) by indirect calorimetry. Data on changes in body weight (5.8+/-6.5 kg) over a follow-up period of 4+/-3 y were available in 74 (49M/25F) of the 92 subjects.

RESULTS

The baseline calculated total energy intake (r=0.25, P=0.028) and RMR (r=-0.28, P=0.016) were significantly associated with changes in body weight. The baseline energy expenditure due to physical activity was not associated with changes in body weight.

CONCLUSION

Using state-of-the-art methods to assess energy intake and expenditure in free-living conditions, we show for the first time that the baseline calculated total energy intake is a determinant of changes in body weight in Pima Indians. These data also confirm that a low RMR is a risk factor for weight gain in this population.

Energy metabolism after 2 y of energy restriction: the biosphere 2 experiment

BACKGROUND

An adaptive decrease in energy expenditure (EE) in response to 6 mo of severely restricted energy intake was shown in a classic semistarvation study-the Minnesota experiment.

OBJECTIVE

Our objective was to examine whether such adaptation also occurs in response to less severe but sustained energy restriction.

DESIGN

Body composition, 1-wk total EE (TEE), 24-h sedentary EE, and spontaneous physical activity were measured in 8 healthy subjects (4 men and 4 women) at the end of a 2-y confinement inside Biosphere 2. Unexpectedly, the food supply was markedly restricted during most of the confinement and all subjects experienced a marked, sustained weight loss (9.1 +/- 6.6 kg; P: < 0.001) from the low-energy (7000-11000 kJ/d), low-fat (9% of energy), but nutrient-dense, diet they consumed.

RESULTS

The TEE inside Biosphere 2, assessed 3 wk before exit, averaged 10700 +/- 560 kJ/d (n = 8). Within 1 wk after exit, the adjusted 24-h EE and spontaneous physical activity were lower in the biospherians (n = 5) than in 152 control subjects (6% and 45%, respectively; both P: < 0.01). Six months after exit and return to an ad libitum diet, body weight had increased to preentry levels; however, adjusted 24-h EE and spontaneous physical activity were still significantly lower than in control subjects.

CONCLUSIONS

In lean humans, an adaptive decrease in EE appears to occur not only in states of life-threatening undernutrition, but also in response to less severe energy restriction sustained over several years.

A comparison of bioimpedance methods for detection of body cell mass change in HIV infection

The maintenance of body cell mass (BCM) is critical for survival in human immunodeficiency virus (HIV) infection. Accuracy of bioimpedance for measuring change (Delta) in intracellular water (ICW), which defines BCM, is uncertain. To evaluate bioimpedance-estimated DeltaBCM, the ICW of 21 weight-losing HIV patients was measured before and after anabolic steroid therapy by dilution (total body water by deuterium - extracellular water by bromide) and bioimpedance. Multiple-frequency modeling- and dilution-determined DeltaICW did not differ. The DeltaICW was predicted poorly by 50-kHz parallel reactance, 50-kHz impedance, and 200 - 5-kHz impedance. The DeltaICW predicted by 500 - 5-kHz impedance was closer to, but statistically different from, dilution-determined DeltaICW. However, the effect of random error on the measurement of systematic error in the 500 - 5-kHz method was 12-13% of the average measured DeltaICW; this was nearly twice the percent difference between obtained and threshold statistics. Although the 500 - 5-kHz method cannot be fully rejected, these results support the conclusion that only the multiple-frequency modeling approach accurately monitors DeltaBCM in HIV infection.

Daily energy expenditure in Mexican and USA Pima indians: low physical activity as a possible cause of obesity

BACKGROUND

Obesity is caused by an imbalance between energy intake and energy expenditure. However, it is unknown whether increased physical activity protects susceptible populations against the development of obesity and type 2 diabetes.

OBJECTIVE

To investigate the potential protective role of environment and physical activity against obesity by measuring total energy expenditure in Mexican and USA Pima Indians.

METHODS

We compared the physical activity level of 40 (17 female and 23 male; 37+/-11 y, 66+/-13 kg) Mexican Pima Indians from a remote, mountainous area of Northwest Mexico, with 40 age-and-sex matched (17 female and 23 male; 37+/-12 y, 93+/-22 kg) Pima Indians from the Gila River Indian Community in Arizona, USA. We measured total energy expenditure (TEE) by doubly labeled water and calculated physical activity by different methods: physical activity level (PAL) as the ratio of TEE on resting metabolic rate (RMR), TEE adjusted for RMR by linear regression, activity energy expenditure adjusted for body weight (AEE), and activity questionnaire.

RESULTS

Physical activity was higher in Mexican Pima Indians when compared with USA Pima Indians as assessed by PAL (1.97+/-0.34 vs 1.57+/-0.16, P<0.0001), TEE adjusted for RMR (3289+/-454 vs 2671+/-454 kcal/day, P<0.0001) and AEE adjusted for body weight (1243+/-415 vs 711+/-415 kcal/day, P<0. 0001). Questionnaires revealed more time spent on occupational activities among Mexican Pima compared with USA Pima (23.9+/-13.3 vs 12.6+/-13.9 h/week, P<0.001).

CONCLUSION

These data support a significant role for physical activity in the prevention of obesity in genetically susceptible populations. International Journal of Obesity (2000)24, 55-59

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.

An improved technique for the 2H/1H analysis of urines from diabetic volunteers

The H2-H2O ambient-temperature equilibration technique for the determination of 2H/1H ratios in urinary waters from diabetic subjects provides improved accuracy over the conventional Zn reduction technique. The standard deviation, approximately 1-2%, is at least a factor of three better than that of the Zn reduction technique on urinary waters from diabetic volunteers. Experiments with pure water and solutions containing glucose, urea and albumen indicate that there is no measurable bias in the hydrogen equilibration technique.

Determinants of total daily energy expenditure: variability in physical activity

Excessive energy intake and/or reduced total daily energy expenditure (TEE) causes obesity. To determine the relationship between obesity and TEE in an obesity-prone population, we measured TEE, 24-h sedentary energy expenditure (SEDEE), and basal metabolic rate (BMR) in 30 Pima Indian men (83.6 +/- 20.0 kg and 31 +/- 9% fat) by the doubly labeled water method and a respiratory chamber. The energy expenditure for physical activity (EEACT) was calculated as TEE - (BMR + 0.1 TEE), where 10% of TEE is an estimate of the thermic effect of food. Fat-free mass was the best single determinant (P < 0.01) of TEE, explaining 48% of its variance. TEE, SEDEE, BMR, and EEACT were 12,010 +/- 2292, 9945 +/- 1559, 7677 +/- 1901, and 3297 +/- 1732 kJ/d, respectively. Because EEACT is dependent on body weight, EEACT/kg body wt (41.7 +/- 23.2 kJ.d-1.kg-1) and TEE/(BMR + 0.1 TEE) (1.39 +/- 0.22) were used as indexes of the level of physical activity. Both indexes correlated negatively with percent body fat (r = -0.56, P < 0.01 and r = -0.42, P < 0.03, respectively). These results suggest that obesity is associated with lower levels of physical activity.

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.

Energy expenditure by doubly labeled water: validation in lean and obese subjects

The doubly labeled water (2H2(18)O) method to assess energy expenditure in free-living conditions has been successfully validated against gas exchange measurements in lean healthy volunteers in both sedentary conditions and during sustained heavy exercise. However, no data are available on obese subjects. We therefore compared the 2H2(18)O method with indirect calorimetry (respiratory chamber) in 12 male subjects covering a wide range of body weight and composition (61-190 kg, 7-41% fat). Isotope pool sizes and elimination rates were calculated from 18O and 2H enrichments in baseline urine samples and in 7-h, 11.5-h, and daily postdose urine samples using the multipoint slope/intercept method. Results were corrected for isotopic fractionation. Mean 7-day energy expenditure in the respiratory chamber varied from 1,851 to 4,105 kcal/day. The doubly labeled water method tended to underestimate energy expenditure (-2.5 +/- 5.8%, not equal to 0, range -14 to +4%), with the larger underestimate observed in heavier and fatter subjects (r = -0.82 and -0.68, P less than 0.02, respectively). The underestimation in heavier subjects might be related to larger sequestration of deuterium during fat synthesis. In conclusion, the doubly labeled water method is a suitable and accurate method to measure energy expenditure in free-living conditions but might provide a slightly underestimated figure in fatter subjects.

Integrated study of low density lipoprotein metabolism and very low density lipoprotein metabolism in non-insulin-dependent diabetes

The metabolisms of VLDL, IDL, and LDL and their interconversions have been studied in ten obese untreated male Pima Indian diabetics compared to 16 age-, sex-, and weight-matched nondiabetics. VLDL was elevated in the diabetics and had abnormal composition, as indicated by a significantly higher ratio of triglyceride/apo B. Fractional catabolic rates for both VLDL apoB and VLDL triglyceride were lower in diabetics, and diabetics had increased production of VLDL triglyceride but not VLDL apoB compared to obese nondiabetics. A higher proportion of VLDL apoB was removed without conversion to LDL in diabetics. LDL cholesterol and apoB were higher in diabetics, but production of LDL apoB was not different from nondiabetics. Fractional catabolic rate for LDL apoB, however, was significantly lower in the diabetics. The data indicate that the triglyceride-rich VLDL in non-insulin-dependent diabetics are less readily converted to LDL, whereas the elevated LDL in this group of diabetics is due to impaired clearance. Thus, decreased conversion of VLDL to LDL and impaired LDL clearance are two opposing phenomena which may influence the LDL concentration of diabetics in either direction. Thus, despite minimal changes in LDL concentration, there are multiple defects in the metabolism of LDL in non-insulin dependent diabetes which may contribute to the increased atherogenesis in this disorder.