Lower resting metabolic rate and higher velocity of weight gain in a prospective study of stunted vs nonstunted girls living in the shantytowns of São Paulo, Brazil.

OBJECTIVE: Previous studies have shown that stunting increases the risk of obesity in developing countries, particularly among girls and women, but the underlying reasons are not known. This study aimed to investigate the relationship between stunting, weight gain, and resting metabolic rate. DESIGN AND SUBJECTS: A prospective study was conducted over 36 months with girls from shantytowns in São Paulo, Brazil. A total of 15 stunted girls (S) were compared with 15 nonstunted (N) ones of similar weight for height ratio. INTERVENTIONS: Resting metabolic rate was measured using indirect calorimetry, and the socioeconomic status was determined by interviews in the household. In addition, body composition was measured by skinfold thickness, while the growth rate was calculated dividing the change in weight and the change in height by the follow-up period. RESULTS: The results of the present study, when combined, revealed that the S group had a lower resting metabolic rate throughout the follow-up period with the differences being significant at 24 and 36 months of follow-up, associated with an increase in the rate of weight gain and a decrease in lean mass, when compared to the N group. CONCLUSIONS: These changes are known to be risk factors for obesity and may help to explain the particularly higher prevalence of obesity in women in urban areas of developing countries.

Why are nutritionally stunted children at increased risk of obesity? Studies of metabolic rate and fat oxidation in shantytown children from São Paulo, Brazil.

BACKGROUND: Previous research suggested that nutritionally stunted children may have increased risk of obesity, but little is known about potential underlying mechanisms. OBJECTIVE: We sought to test the hypothesis that stunted children have a low metabolic rate and impaired fat oxidation relative to nonstunted children. DESIGN: The subjects were 58 prepubertal boys and girls aged 8-11 y from the shantytowns of São Paulo, Brazil. Twenty-eight were stunted (height-for-age z score <-1.5) and 30 had similar weight-for-height but normal height (height-for-age z score >-1.5). Parents of children in the 2 groups had equivalent height and body mass index values. Fasting and postprandial energy expenditure, respiratory quotient (RQ), and substrate oxidation were measured with indirect calorimetry in a 3-d resident study in which all food was provided and body composition was measured with dual-energy X-ray absorptiometry. RESULTS: Stunted children had normal resting energy expenditure relative to body composition compared with control children (4559 +/- 90 and 4755 +/- 86 kJ/d, respectively; P: = 0.14) and had normal postprandial thermogenesis (2.4 +/- 0.3% and 2.0 +/- 0.3% of meal load, respectively; P: = 0.42). However, fasting RQ was significantly higher in the stunted group (0.92 +/- 0.009 compared with 0.89 +/- 0.007; P: = 0.04) and consequently, fasting fat oxidation was significantly lower (25 +/- 2% compared with 34 +/- 2% of energy expenditure; P: < 0.01). CONCLUSIONS: Childhood nutritional stunting is associated with impaired fat oxidation, a factor that predicted obesity in other at-risk populations. This finding may help explain recent increases in body fatness and the prevalence of obesity among stunted adults and adolescents in developing countries.

Dietary energy requirements of young and older women determined by using the doubly labeled water method.

There is little information on the effects of age on energy requirements in women. This issue was investigated in a cross-sectional study of 10 normal-weight young women aged 25.2 +/- 1.1 y (mean +/- SEM) and 10 normal-weight older women aged 74.0 +/- 1.4 y. In a 9-d study, measurements were made of free-living total energy expenditure (TEE) by using the doubly labeled water technique, body composition by using hydrodensitometry, and resting energy expenditure (REE) by using indirect calorimetry. Mean values for reported levels of strenuous activity were within the expected range in both groups (31 +/- 13 min/d in the young group and 7 +/- 2 min/d in the older group). Energy requirements expressed as the ratio of TEE to REE were 1.80 +/- 0.10 and 1.62 +/- 0.06 (P < 0.01) in the young and older group, respectively. When values for REE predicted from body weight (pREE) were used, as suggested in the current recommended dietary allowances (RDAs), the ratios of TEE to pREE in the two groups were 1.85 +/- 0.10 and 1.54 +/- 0.04 (P < 0.05). The RDAs significantly under-predicted the energy requirements of the young group (P < 0.05), but there was no significant underprediction in the older group. Although obtained in a relatively small number of subjects, these results provide no evidence to indicate that the current RDAs underestimate the energy requirements of older women, in contrast with previous observations of an underestimation of energy requirements by the RDAs in older men.

Energy expenditure of stunted and nonstunted boys and girls living in the shantytowns of São Paulo, Brazil.

BACKGROUND: Stunting increases the risk of obesity in developing countries, particularly in girls and women, but the underlying reason is not known. OBJECTIVE: Our objective was to test the hypothesis that stunted children have lower energy expenditure than do nonstunted children, a factor that has predicted an increased risk of obesity in other high-risk populations. DESIGN: A cross-sectional study was conducted in shantytown children from São Paulo, Brazil. Twenty-eight stunted children aged 8-11 y were compared with 30 nonstunted children with similar weight-for-height. Free-living total energy expenditure (TEE) was measured over 7 d by using the doubly labeled water method. In addition, resting energy expenditure (REE) was measured by indirect calorimetry and body composition was measured by dual-energy X-ray absorptiometry. RESULTS: There were no significant associations between stunting and any measured energy expenditure parameter, including REE adjusted for weight (f1.gif" BORDER="0"> +/- SEM: 4575 +/- 95 compared with 4742 +/- 91 kJ/d, in stunted and nonstunted children, respectively) and TEE adjusted for weight (8424 +/- 239 compared with 8009 +/- 221 kJ/d, in stunted and nonstunted children, respectively). In multiple regression models that included fat-free mass and fat mass, girls had significantly lower TEE than did boys (P: < 0.05) but not significantly lower REE (P: = 0.17). CONCLUSIONS: There was no association between stunting and energy expenditure after differences between groups in body size and composition were accounted for. However, the girls had lower TEE than did boys, which may help to explain the particularly high risk of obesity in stunted adolescent girls and women in urban areas of developing countries.

Equations for predicting the energy requirements of healthy adults aged 18-81 y.

BACKGROUND: Recent studies have questioned the accuracy of using the current recommended dietary allowances (RDAs) to predict usual energy requirements in adults. OBJECTIVE: We developed equations to predict adult energy requirements from simple anthropometric and laboratory measures by using the doubly labeled water method to determine each subject's total energy expenditure (TEE), which is equal to usual energy requirements in weight-stable individuals. DESIGN: This was a cross-sectional study conducted with 93 healthy, free-living adults [44 men and 49 women; body mass index range (in kg/m2): 18.4-31.8] aged 18-81 y. Body fat and fat-free mass were measured by underwater weighing, physical activity was estimated by using activity monitors, and resting energy expenditure was determined by indirect calorimetry. Information on anthropometric variables and reported strenuous activity was also collected. RESULTS: Three regression equations were developed and verified for accuracy by using bootstrap analysis and doubly labeled water data published by other research groups. The first equation used information on only age, weight, height, and sex and had an SEE for prediction of TEE of 1.80 MJ/d. The second and third equations used different combinations of basic and laboratory data and had SEEs of 1.55 and 1.65 MJ/d, respectively. With use of the same analytic approaches, the RDAs for energy were shown to significantly underestimate usual energy needs by approximately 10%; the extent of underestimation was significantly greater for subjects with high TEEs than for subjects with low TEEs. CONCLUSION: Regression equations based on doubly labeled water measurements of TEE appear to be more accurate than the current RDAs for predicting energy requirements in healthy, nonobese adults living in affluent countries.

Evaluation of four methods for determining energy intake in young and older women: comparison with doubly labeled water measurements of total energy expenditure.

The accuracy and precision of four different food intake assessment methods were evaluated in young and older women by comparing reported energy intakes with doubly labeled water measurements total energy expenditure (TEE). A study lasting 8 d was conducted in 10 young women aged 25.2+/-1.1 y (-x+/-SEM) and in 10 older women aged 74.0+/-1.4 y. Free-living TEE was measured over 7 d and food consumption was determined from weighed food intake data (7 d), a 24-h food recall (in duplicate), and two different food-frequency questionnaires [Fred Hutchinson Cancer Research Center (FHCRC)/Block and Willett, both in duplicate]. In addition, body composition was determined by using hydrodensitometry, and strenuous physical activity and the extent of dietary restraint were determined by questionnaire. In young women, 24-h recall gave mean energy intakes that were closest to measures of TEE (-0.34+/-3.71 MJ/d compared with TEE, P=0.178), and energy intakes by food-frequency questionnaires were the only intake data that correlated significantly with individual values for TEE (P<0.05). In older women, food-frequency questionnaires gave mean energy intakes that were closest to measured TEE (+0.53+/-2.95 MJ/d with the Willett questionnaire and -1.19+/-3.02 MJ/d with FHCRC/Block questionnaire). No energy intake data from this group correlated significantly with values for TEE. The 7-d weighed dietary intakes were significantly lower than measured TEE in both young and older women (-2.0 MJ/d in young and older women combined, P<0.001), and did not correlate significantly with values for TEE, although they did most closely mirror the mean difference in TEE between the young and older women (2.30 MJ/d for TEE and 2.11 MJ/d for 7-d weighed intake). These data suggest that none of the methods studied gave accurate estimates of the usual energy requirements of individual subjects. In addition, the results suggest that for some types of studies, simple methods for assessing group mean dietary intake may actually give more accurate information than weighed dietary intakes.

Meal palatability, substrate oxidation and blood glucose in young and older men.

We investigated the effects of food palatability on the thermic effect of feeding (TEF), substrate oxidation and circulating glucose and insulin. Healthy young men (23.4+/-1.0, SD, years, n=10) and older men (69.4+/-1.3, years, n=9) were resident in a metabolic unit for two 2-day study periods. On the second day of each period, they consumed in random order either a palatable test meal containing 2.93 MJ or a nonpalatable control meal containing the same foods in identical amounts but blended and freeze-dried into biscuit form. TEF and respiratory quotient (RQ) were measured over 6 h and blood samples were taken for measurement of glucose and insulin. Age group had no effect on TEF, RQ or circulating glucose other than to delay the time of peak TEF (P<0.002 for both meals). There was no significant effect of meal type on TEF, but RQ and circulating glucose were higher following consumption of the palatable meal (P<0.001 for both parameters). These results suggest that over 6 h postprandial, consumption of palatable foods does not increase TEF, but is instead associated with increased glycemic response and increased carbohydrate oxidation. These changes, combined with previous work on the glycemic index, predict an accelerated return of hunger and increased energy intake at subsequent meals following consumption of palatable vs. control foods. Further studies are needed to examine the possible mechanism for this previously suggested "second meal" effect of diet palatability on energy intake.

Use of food quotients in human doubly labeled water studies: comparable results obtained with 4 widely used food intake methods.

Information on the macronutrient composition of the diet is needed in doubly labeled water studies to convert measured rates of carbon dioxide production into values for total energy expenditure. There is no general consensus, however, about the best method to determine food intake for this purpose. Four common methods of measuring food intake (7-day weighed food intake, 24-hour recall, and Fred Hutchinson Cancer Research Center/Block and Willett food frequency questionnaires) were tested for their ability to provide comparable food quotient and total energy expenditure data in doubly labeled water studies in 10 young and 10 older women. All methods gave mean values for total energy expenditure that were within 1% of each other. Individual values obtained using the 24-hour recall and food frequency questionnaires were within +/- 3% (standard deviation) of values determined using data from the 7-day weighed food record. These results suggest that it is not necessary to use time-consuming and expensive 7-day food records in doubly labeled water studies; instead, food intake data obtained more easily by 24-hour recall or food frequency questionnaire can provide comparable data.

Food consumed does not account for the higher prevalence of obesity among stunted adults in a very-low-income population in the Northeast of Brazil (Maceió, Alagoas).

OBJECTIVE: To study the food pattern of stunted and nonstunted, obese and nonobese individuals in a very-low-income population. DESIGN: A household survey. SETTING: Slum set up by the 'Homeless Movement', city of Maceió (Alagoas), Brazil. SUBJECTS AND METHODS: A total of 532 adults classified by sex, stature (Z -2s.d. of the NCHS curves), and body mass index (BMI) were compared using the following variables: waist circumference, waist-hip circumference ratio (W/H), percentage body fat (skinfold thickness and bioelectrical impedance), and food intake (24-h recall). RESULTS: The prevalence of stunting was 22.6%. In all, 30% of the stunted subjects were overweight or obese, compared with 23% for the nonstunted individuals (P<0.05). In women, logistic regression analysis showed a strong association among weight, abdominal fat, and stunting (r=0.81). No significant differences were observed in the values of W/H or in the qualitative menu of the different categories. Energy intake was below the RDA figures (about 63%). There was similarity among the groups regarding the proportion of macronutrients, except for the fact that stunted obese women ingested less fat and protein than nonstunted obese women. Stunted obese individuals consumed less energy (5962 kJ) than the population as a whole (6213 kJ), an amount far lower than their average needs, which were calculated on the basis of their shorter stature (8109 kJ). CONCLUSION: The observed energy consumption seems compatible with the panorama of undernutrition present in the population, but it does not explain the high prevalence of obesity detected.

Increase in skeletal muscle protein content by the beta-2 selective adrenergic agonist clenbuterol exacerbates hypoalbuminemia in rats fed a low-protein diet.

This investigation examined how the nutritional status of rats fed a low-protein diet was affected when the animals were treated with the beta-2 selective agonist clenbuterol (CL). Males (4 weeks old) from an inbred, specific-pathogen-free strain of hooded rats maintained at the Dunn Nutritional Laboratory were used in the experiments (N = 6 rats per group). CL treatment (Ventipulmin, Boehringer-Ingelheim Ltd., 3.2 mg/kg diet for 2 weeks) caused an exacerbation of the symptoms associated with protein deficiency in rats. Plasma albumin concentrations, already low in rats fed a low-protein diet (group A), were further reduced in CL rats (A = 25.05 +/- 0.31 vs CL = 23.64 +/- 0.30 g/l, P < 0.05). Total liver protein decreased below the level seen in either pair-fed animals (group P) or animals with free access to the low-protein diet (A = 736.56 +/- 26 vs CL = 535.41 +/- 54 mg, P < 0.05), whereas gastrocnemius muscle protein was higher than the values normally described for control (C) animals (C = 210.88 +/- 3.2 vs CL = 227.14 +/- 1.7 mg/g, P < 0.05). Clenbuterol-treated rats also showed a reduction in growth when compared to P rats (P = 3.2 +/- 1.1 vs CL = -10.2 +/- 1.9 g, P < 0.05). This was associated with a marked decrease in fat stores (P = 5.35 +/- 0.81 vs CL = 2.02 +/- 0.16 g, P < 0.05). Brown adipose tissue (BAT) cytochrome oxidase activity, although slightly lower than in P rats (P = 469.96 +/- 16.20 vs CL = 414.48 +/- 11.32 U/BAT x kg body weight, P < 0.05), was still much higher than in control rats (C = 159.55 +/- 11.54 vs CL = 414.48 +/- 11.32 U/BAT x kg body weight, P < 0.05). The present findings support the hypothesis that an increased muscle protein content due to clenbuterol stimulation worsened amino acid availability to the liver and further reduced albumin synthesis causing exacerbation of hypoalbuminemia in rats fed a low-protein diet.

Plasma kallikrein clearance by the liver in food-restricted rats.

We measured the clearance rate of plasma kallikrein by the liver in three groups of rats: one recently weaned, and two seven weeks old (control and food-restricted groups). The clearance rates were similar in the three groups when expressed as units/g liver. The livers of the recently weaned and food-restricted rats were, however, smaller than those of the controls and consequently their livers cleared plasma kallikrein less efficiently.

[Breastfeeding in shantytowns: an educational program through home visits]. / Aleitamento materno em favelas: um programa de incentivo a través de visitas domiciliares.

This is a study of breastfeeding length, with and without a community educational program. It was done through home visits to 125 women residing in Vila Marianaís shantytowns in the city of São Paulo. It was found that breastfeeding lasts an average of more than 6 months after the educational intervention. When comparing the group that received education with the one that didnít, it was observed that in the former the percentage of children breastfed for 6 months or longer was 64%, while in the control group it was 17% (p < 0.001). This shows a significant increase in the number of mothers who nursed their children after an educational program promoting breastfeeding.

[Metabolic and cardiorespiratory responses to maximal and submaximal exercise in eutrophic and stunted girls]. / Respostas metabólicas e cardiorrespiratórias ao exercício máximo e submáximo em meninas eutróficas e com desnutrição pregressa.

OBJECTIVE: The metabolic and cardiovascular responses of eutrophic girls and girls who underwent early undernutrition, were examined during physical exercise, in order to verify whether previous undernutrition could, in addition to cause a deficit in the children's height, and limit their functional capability to perform a maximal and submaximal exercise in an ergometric bicycle. SUBJECTS: Our sample was composed of 24 girls, of which 12 were eutrophic, with 9.13 +/- 0.79 years (mean +/- s.d.), 27.64 +/- 3.64 kg of body weight, and 131.31 +/- 6.04 cm in height. The 12 early undernourished girls were 9.75 +/- 1.1 years old, 25.16 +/- 2.33 kg, and 125.06 +/- 3.9 cm high. MEASUREMENTS: The method included clinical evaluation and ergo-spirometric test on an ergometric bicycle, from which all the metabolic and cardiac-respiratory variables were obtained and analyzed. The test protocol was an initial two minutes period with 25 watts, followed by increments of 15 watts every two minutes, until exhaustion. RESULTS: Analysis of the results of the test of maximal effort did not reveal significant differences between eutrophic (E) and early undernourished (UN) girls in any of the variables: VO2max expressed in l/min (E = 1.11 +/- 0.25; UN = 1.02 +/- 0.19); VO2max expressed in ml/min/kg (E = 40.23 +/- 6.98; UN = 40.53 +/- 6.32), VEmax (E = 40.61 +/- 8.79; UN = 38.25 +/- 8.95), R (E = 1.13 +/- 0.07; UN = 1.13 +/- 0.05), HRmax (E = 195.33 +/- 9.13; UN = 193.85 +/- 11.18), previous % HRmax (E = 92.87 +/- 4.33; UN = 92.80 +/- 4.87), and maximum watts (E = 90.00 +/- 20.56; UN = 91.25 +/- 11.33). Analysis of the results obtained in test of submaximal effort, reflected by the intensity of effort in the anaerobic threshold (AT), showed differences between the groups in the following variables: VO2max expressed in l/min. (E = 0.77 +/- 0.14; UN = 0.62 +/- 0.13), % of VO2max (E = 70.07 +/- 7.52; UN = 61.21 +/- 9.83), HR (E = 166.58 +/- 14.25; UN = 146.33 +/- 17.40), % HRmax (E = 85.31 +/-6.41; UN = 75.50 +/- 7.73), VE (E = 24.18 +/- 5.81; UN = 17.69 +/- 4.30), % VEmax (E = 59.64 +/- 8.45; UN = 46.95 +/- 10.59). No differences were found for VO2max, expressed in l/min/kg (E = 28.06 +/- 4.87; UN = 24.81 +/- 5.31) and watts (E = 51.25 +/- 17.47; UN = 45.00 +/- 9.77). CONCLUSION: The reestablishment of the ratio weight/height in early undernourished girls is also useful to indicate lack of limitation of functional capability to perform physical exercises.

[Influence of socioeconomic conditions in the nutritional changes and at rest metabolic rate in school children living in shantytowns of the city of São Paulo, Brazil]. / Influência das condições socioeconômicas nas alterações nutricionais e na taxa de metabolismo de repouso em crianças escolares moradoras em favelas no município de São Paulo.

PURPOSE: A cross-sectional study was carried out to characterize the alterations in the resting metabolic rate (RMR), and socioeconomic conditions of 15 stunted (DP= height/age < 95% and 110% (3) weight/height >90%) and 15 nonstunted (EU= height/age > 95% and 110% (3) weight/height >90%) school girls living in shantytowns of São Paulo. METHODS: Resting metabolic rate was measured using indirect calorimetry. Socioeconomic data was collected during home visits by administration of a questionnaire. RESULTS: The mildly stunted group had a higher RMR when expressed as Kcal/kg body weight (EU= 40,5 Kcal/kg/day; DP=44,4 Kcal/kg/day; p<0.05) and lean body mass (EU= 49, 2 Kcal/kg/day; DP=52,5 Kcal/kg/day; p<0.05). Stunting was associated with maternal illiteracy (EU= 13,3%; DP=57,1%; p<0.05), income per capita (EU=US$107,14; DP=US$54,40; p< 0.05), number of parasites per child (EU=0; DP=1; p<0.05), birth order (EU=2; DP=4; p< 0.05), and number of siblings (EU=4; DP=6; p<0.01). Stunting was best predicted by income per capita and maternal illiteracy by using multiple logistic regression. CONCLUSIONS: Although the two groups had normal weight/height, the group with mild stunting showed socioeconomic and metabolic alterations, typical of a malnourished condition.

[Evaluation of nutritional recovery pattern of malnourished children examined at the center of Recovery and Educational Nutrition, Brazil]. / Avaliação do padrão de recuperação nutricional de crianças desnutridas atendidas no centro de recuperação e educação nutricional.

PURPOSE: To assess the pattern of nutritional recovery in malnourished children. This prospective analysis was conducted between September 1995 and November 1996 at the Center for Recovery and Nutrition Education (CREN) in São Paulo, Brazil. Of the thirty-eight children studied, 47.4% were infants (nine girls and nine boys) and 52.6% preschool children (twelve boys and eight girls). METHOD: Thirty eight children were studied by velocity of W/A and H/A gain in standard deviation or Z score, according to weight and height median of NCHS. RESULTS: There was a statistically significant increase in the weight-for-age (W/A)(p = 0.012), height-for-age (H/A) (p = 0.001) from the time of admission. The difference in the velocity of W/A gain between infants (0.299-Z/year) and preschool children (0.684-Z/year) with more than six months of treatment, was found to be statistically significant (p = 0.038). The difference in the velocity of H/A gain for infants (0.794-Z/year) and for preschool children (0.506-Z/year), was not statistically significant (p = 0.166). In regards to gender, there was not a statistically significant difference between boys and girls in the velocity of W/A gain (0.540 and 0.524-Z/year, respectively). The difference in velocity of H/A gain was statistically significant, 0.485-Z/year for boys and 0.856-Z/year for girls (p = 0.043). CONCLUSION: These findings show that there are differences in the nutritional recovery patterns between gender and age groups.

Evidence for impaired insulin production and higher sensitivity in stunted children living in slums.

The objective of the present study was to investigate the changes in glucose and insulin metabolism in nutritionally stunted children that can be involved in the appearance of chronic diseases in adulthood. For this purpose, sixty-one children were selected, thirty-five boys and twenty-six girls, residents of slums in São Paulo, Brazil. The children were classified according to the height-for-age as stunted (-1.5 Z-score; n 40). The glucose and insulin plasma levels were determined and, from these values, the indexes that evaluate the pancreatic beta-cell function (homeostasis model assessment (HOMA-B)) and insulin sensitivity (HOMA-S) were assessed. Stunted children showed lower values of fasting insulin than those of the non-stunted group (boys: 29.7 (SD 14.9) v. 50.4 (SD 29.2) pmol/l, P=0.019; girls: 34.4 (SD 12.6) v. 62.3 (SD 28.7) pmol/l, P=0.016) but the glucose levels were similar (boys: 4.6 (SD 0.3) v. 4.5 (SD 0.3) mmol/l; girls: 4.2 (SD 0.3) v. 4.4 (SD 0.3) mmol/l). Stunted children showed lower HOMA-B values (boys: 83 (SD 22) % v. 115 (SD 36) %, P=0.011; girls: 107 (SD 23) % v. 144 (SD 46) %, P=0.045) and higher HOMA-S values (boys: 196 (SD 92) % v. 120 (SD 62) %, P=0.014; girls: 159 (SD 67) % v. 98 (SD 57) %, P=0.016). The results show a decreased activity of beta-cell function and increased insulin sensitivity in stunted children. The decreased beta-cell function of this group may strongly predict type 2 diabetes.

Lowering of plasma triiodothyronine level and sympathetic activity does not alter hypoalbuminaemia in rats fed on a diet of low protein concentration.

Previous studies have described high plasma triiodothyronine (T3) concentrations and sympathetic activity in rats fed on low-protein diets. The present investigation examined how the nutritional status of rats fed on a low-protein diet was affected when these hormonal changes were reduced by drug administration. The low-protein diet (LP group) prevented growth, reduced plasma albumin levels, elevated plasma T3 concentration, and increased both the weight of the interscapular brown adipose tissue (BAT) and the activity of BAT cytochrome c oxidase (EC 1.9.3.1). Lowering the plasma T3 concentration (with carbimazole; CA group) elevated the plasma insulin concentration, promoted a small increase in the plasma albumin concentration and caused weight gain in comparison with the LP group. Reduction of sympathetic activity (with alpha-methyl-p-tyrosine; MT group) promoted a small elevation in plasma albumin concentration accompanied by a diminished T3 concentration, BAT weight, and an increase in fat deposition in relation to LP rats. In a second experiment, simultaneous lowering of the plasma T3 concentration and sympathetic activity (CA/MT group) resulted in weight gain associated with elevated plasma insulin concentration and fat deposition and a marked reduction in BAT cytochrome c oxidase activity. However no change in the hypoalbuminaemia was observed. The results of the present study suggest that in spite of the previously described increase in metabolic rate in fed on a diet with low-protein concentration when compared with controls, the mechanisms involved in the control of BAT activity and fat deposition seem to be independent of those which cause liver protein depletion and hypoalbuminaemia.

Evidence suggesting that the elevated plasma triiodothyronine concentration of rats fed on protein deficient diets is physiologically active.

Some metabolic indicators of thyroid hormone activity have been investigated in rats fed on either protein-deficient or energy-restricted diets. Rats were divided into three groups. Control animals were maintained on a diet of protein energy: total energy (P:E) value of 0.20, while the low-protein group (LP) were allowed ad lib. access to food of P:E 0.03. Energy-restricted (ER) rats were given limited amounts of a control diet (P:E 0.20) such that their rate of growth matched that of LP animals. Animals fed on the LP diet had elevated plasma concentrations of both total and free triiodothyronine (T3) concentrations whereas those on the ER regiment showed values below those of controls. The activities of mitochondrial alpha-glycerol-3-phosphate dehydrogenase (EC 1.1.99.5) and of the alpha-glycerol-3-phosphate shuttle system were elevated in the liver of LP rats, but malate-aspartate shuttle operation was reduced. All three activities were reduced in ER animals. Cytochrome c oxidase (EC 1.9.3.1) activity of brown adipose tissue indicated a high rate of thermogenic activity in this tissue in LP rats, but ER animals showed some evidence of below normal function. The results indicate that both the raised plasma T3 of LP rats and the reduced levels observed in ER animals are physiologically significant.

Intrauterine food restriction is associated with obesity in young rats.

The purpose of this study was to examine the effects of malnutrition during the first 2 wk of intrauterine life on the regulation of energy metabolism and the activity of brown adipose tissue in rats at 53 d of age. Intrauterine malnutrition led to an imbalance in the control of energy metabolism that was influenced by gender. In males, the intrauterine malnutrition resulted in impairment of normal weight gain and fat deposition during 1 to 53 d of age, in association with low plasma total triiodothyronine concentration, in spite of normal food intake. In contrast, the intrauterine malnutrition in females led to a marked fat accumulation by 53 d of age with normal food intake, and decreased brown adipose tissue weight, protein content and cytochrome c oxidase activity, indicating a lower sympathetic activity. These data indicate that nutrient availability during the first 2 wk of intrauterine life determines the control of energy utilization during early post-weaning period.