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1.
Eur J Clin Nutr ; 71(4): 558-560, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-27901030

RESUMO

Comparison of percent fat mass across different body composition analysis devices is important given variation in technology accuracy and precision, as well as the growing need for cross-validation of devices often applied across longitudinal studies. We compared EchoMRI-AH and Lunar iDXA quantification of percent body fat (PBF) in 84 adults (43M, 41F), with the mean age 39.7±15.9 years and body mass index (BMI) 26.2±5.3 kg/m2. PBF correlated strongly between devices (r>0.95, P<0.0001). A prediction equation was derived in half of the subjects, and the other half were used to cross-validate the proposed equation (EchoMRI-AH PBF=[(0.94 × iDXA PBF)+(0.14 × Age)+(3.3 × Female)-8.83). The mean PBF difference (predicted-measured) in the validation group was not different from 0 (diff=0.27%, 95% confidence interval: -0.42-0.96, P=0.430). Bland-Altman plots showed a bias with higher measured PBF on EchoMRI-AH versus iDXA in all 84 subjects (ß=0.13, P<0.0001). The proposed prediction equation was valid in our cross-validation sample, and it has the potential to be applied across multicenter studies.


Assuntos
Absorciometria de Fóton/estatística & dados numéricos , Composição Corporal , Imageamento por Ressonância Magnética/estatística & dados numéricos , Imagem Corporal Total/estatística & dados numéricos , Absorciometria de Fóton/métodos , Adulto , Índice de Massa Corporal , Intervalos de Confiança , Feminino , Voluntários Saudáveis , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Imagem Corporal Total/métodos
2.
Appetite ; 67: 1-7, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23523668

RESUMO

The aim was to investigate relationships between activity related energy expenditure (AREE), appetite ratings and energy intake (EI) in a sample of 40 male (26.4years; BMI 23.5kg/m(2)) and 42 female (26.9years; BMI 22.4kg/m(2)) participants. AREE was expressed as the residual value of the regression between total daily EE (by doubly labeled water) and resting EE (by indirect calorimetry). EI was measured using an ad libitum buffet meal and visual analogue scales measured subjective appetite ratings before and after the meal. AREE was divided into low, middle and high sex-specific tertiles. General linear models were used to investigate differences in appetite ratings and EI across AREE tertiles. Before the meal, males in the high AREE tertile had significantly lower desire to eat and lower prospective food consumption and higher feelings of fullness compared to those in the low tertile. Males in the middle tertile had significantly higher satiety quotients after the meal and lower EI compared to the other tertiles. No significant differences across tertiles were found in females. Sex differences in relationships between AREE, appetite ratings and EI may lead to differing patterns of EI and subsequent weight maintenance.


Assuntos
Apetite/fisiologia , Peso Corporal/fisiologia , Ingestão de Energia/fisiologia , Metabolismo Energético/fisiologia , Atividade Motora/fisiologia , Adulto , Calorimetria Indireta , Feminino , Humanos , Masculino , Análise de Regressão , Saciação , Fatores Sexuais
3.
Int J Obes (Lond) ; 35(9): 1241-6, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21224826

RESUMO

BACKGROUND: The sensitivity to detect small changes in body composition (fat mass and fat-free mass) largely depends on the precision of the instrument. We compared EchoMRI-AH and dual-energy X-ray absorptiometry (DXA) (Hologic QDR-4500A) for estimating fat mass in 301 volunteers. METHODS: Body composition was evaluated in 136 males and 165 females with a large range of body mass index (BMI) (19-49 kg m(-2)) and age (19-91 years old) using DXA and EchoMRI-AH. In a subsample of 13 lean (BMI=19-25 kg m(-2)) and 21 overweight/obese (BMI>25 kg m(-2)) individuals, within-subject precision was evaluated from repeated measurements taken within 1 h (n=3) and 1 week apart (mean of three measurements taken on each day). RESULTS: Using Bland-Altman analysis, we compared the mean of the fat mass measurements versus the difference in fat mass measured by both instruments. We found that EchoMRI-AH quantified larger amount of fat versus DXA in non-obese (BMI<30 kg m(-2) (1.1 kg, 95% confidence interval (CI(95)):-3.7 to 6.0)) and obese (BMI ≥ 30 kg m(-2) (4.2 kg, CI(95):-1.4 to 9.8)) participants. Within-subject precision (coefficient of variation, %) in fat mass measured within 1 h was remarkably better when measured by EchoMRI-AH than DXA (<0.5 versus <1.5%, respectively; P<0.001). However, 1-week apart within-subject variability showed similar values for both instruments (<2.2%; P=0.15). CONCLUSIONS: EchoMRI-AH yielded greater fat mass values when compared with DXA (Hologic QDR-4500A), particularly in fatter subjects. EchoMRI-AH and DXA showed similar 1-week apart precision when fat mass was measured both in lean and overweight/obese individuals.


Assuntos
Absorciometria de Fóton , Composição Corporal , Imageamento por Ressonância Magnética , Imagem Corporal Total , Adulto , Idoso , Idoso de 80 Anos ou mais , Distribuição da Gordura Corporal , Índice de Massa Corporal , Impedância Elétrica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Adulto Jovem
4.
Int J Obes Relat Metab Disord ; 27(12): 1578-83, 2003 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12975636

RESUMO

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.


Assuntos
Metabolismo Basal/fisiologia , Ingestão de Energia/fisiologia , Indígenas Norte-Americanos , Obesidade/fisiopatologia , Aumento de Peso/fisiologia , Adulto , Arizona , Calorimetria Indireta/métodos , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade/etnologia , Estudos Prospectivos
5.
Int J Obes Relat Metab Disord ; 26(12): 1629-32, 2002 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12461680

RESUMO

Leptin regulates body weight by its receptor-mediated anorectic, thermogenic and antisteatotic effects. Recently, lower leptin binding to the soluble form of the leptin receptor (LEPR) was shown in carriers of the Arg223-encoding allele of the Gln223Arg polymorphism of the LEPR. To investigate whether this variant influences energy metabolism and adiposity in Pima Indians, we genotyped non-diabetic Pima Indians in whom we had measured body composition and 24 h energy expenditure (24 h EE), physical activity level (PAL) and 24 h respiratory quotient (24 h RQ) in a respiratory chamber (n=268) and who had undergone percutaneous fat biopsies from the periumbilical region (n=184). Genotype was not associated with percent body fat (P>0.39), but was associated with 24 h EE, PAL and mean subcutaneous abdominal adipocyte size (SAAS all P<0.05). Homozygotes for the Arg223-encoding allele had lower 24 h EE (P=0.04) and PAL (P=0.007), but larger SAAS (P=0.01) than Gln homozygotes. These findings are consistent with a role of the Gln223Arg polymorphism in reducing peripheral and central leptin binding to the LEPR in humans. However, these effects do not seem to have a major impact on adiposity in this population.


Assuntos
Metabolismo Energético/genética , Indígenas Norte-Americanos/genética , Metabolismo dos Lipídeos , Atividade Motora/genética , Polimorfismo Genético/genética , Receptores de Superfície Celular/genética , Adipócitos/citologia , Adulto , Tamanho Celular , Feminino , Genótipo , Homozigoto , Humanos , Masculino , Receptores para Leptina
6.
Ann Endocrinol (Paris) ; 63(2 Pt 1): 96-105, 2002 Apr.
Artigo em Francês | MEDLINE | ID: mdl-11994669

RESUMO

Obesity is a risk factor for many diseases including cardio-vascular disease, type 2 diabetes, and certain forms of cancer, among others. Obesity results from a chronic imbalance between calorie intake and energy expenditure. Genetic factors obviously play an important role in weight gain, but only in certain environments. The principal cause of the obesity epidemic is not clear: is obesity due to excessive food intake, a dynamic reduction in energy expenditure, or an association of these two factors? However, most obese subjects gain weight because of an inaptitude to adjust energy expenditure in response to excessive food intake. In this article, we review briefly the respective role of genes and environment in the development of obesity, then describe metabolic risk factors involved. Longitudinal studies conducted in Pima Indians have demonstrated that a relative decrease in basal metabolism, weak lipid oxidation in the fasting state, reduced spontaneous physical activity, and lower sympathetic nervous system activity are risk factors for obesity. Unlike our growing knowledge of food intake regulation, little is known about the control of energy expenditure. New discoveries should provide information on obesity susceptibility genes and increase the chances of developing new anti-obesity treatments.


Assuntos
Metabolismo Energético/fisiologia , Obesidade/fisiopatologia , Animais , Humanos , Modelos Biológicos , Fatores de Risco
7.
Int J Obes Relat Metab Disord ; 25(10): 1481-6, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11673770

RESUMO

OBJECTIVE: During a stay in a respiratory chamber without an exercise protocol, physical activity is limited to activities of daily living, change of posture and 'fidgeting,' collectively referred to as spontaneous physical activity (SPA). SPA is quite variable among individuals and is a heritable trait. A low SPA during a chamber stay is a predictor of weight gain in men. However, it remains to be established whether physical activity in a respiratory chamber relates to physical activity under habitual, free-living conditions. The purpose of the present study was to determine whether physical activity in a chamber is correlated to habitual, free-living physical activity. DESIGN: Fifty healthy, non-diabetic Pima Indians (30 M/20 F, 30+/-6 y; 37+/-10% body fat; means+/-s.d.) completed a 24 h stay in the respiratory chamber followed by a 7 day measurement of habitual, free-living energy expenditure by doubly labeled water. Free-living physical activity was expressed as activity energy expenditure (AEE(FL); daily energy expenditure-(sleeping metabolic rate+thermic effect of food)), physical activity level (PAL(FL); daily energy expenditure/sleeping metabolic rate) and body-size independent activity units. Activity during the chamber stay was expressed as PAL(Ch), AEE(Ch), and based on radar sensor measurements, as percentage of time with activity (SPA(Radar)). RESULTS: AEE(FL) (averaging 930+/-310 kcal/day (3.89+/-1.30 MJ/day)) was correlated to AEE(CH) (averaging 440+/-160 kcal/day (1.84+/-0.67 MJ/day)) and higher in men than in women (r=0.53, P=0.003) and r=0.53, P=0.02, respectively). Likewise, PAL(FL) (averaging 1.75+/-0.21) was correlated to PAL(Ch) (averaging 1.42+/-0.10) and higher in men than in women (r=0.49, P=0.006 and r=0.42, P=0.02, respectively). Free-living activity expressed in body-size independent activity units (averaging 17.8+/-7.0) was correlated to SPA(Radar) (averaging 6.4+/-1.7) with no effect of sex (r=0.30, P=0.03). CONCLUSION: Physical activity in a respiratory chamber was correlated to habitual physical activity, whether expressed as AEE, PAL or body-size independent activity units, providing a plausible explanation for the demonstrated association between a low SPA in the chamber and weight gain. The study encourages further studies of the genetic and non-genetic determinants of SPA and non-exercise activity thermogenesis (NEAT).


Assuntos
Atividades Cotidianas , Composição Corporal/fisiologia , Metabolismo Energético/fisiologia , Termogênese/fisiologia , Adulto , Metabolismo Basal/fisiologia , Água Corporal/química , Calorimetria Indireta , Feminino , Humanos , Indígenas Norte-Americanos , Marcação por Isótopo , Masculino , Atividade Motora
9.
Int J Obes Relat Metab Disord ; 24(1): 55-9, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10702751

RESUMO

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


Assuntos
Povo Asiático/genética , Diabetes Mellitus Tipo 2/epidemiologia , Metabolismo Energético/genética , Indígenas Norte-Americanos/genética , Obesidade/epidemiologia , Adulto , Arizona/epidemiologia , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/prevenção & controle , Exercício Físico , Feminino , Humanos , Modelos Lineares , Masculino , México/epidemiologia , Obesidade/genética , Obesidade/prevenção & controle , Inquéritos e Questionários
10.
J Clin Endocrinol Metab ; 85(3): 1087-94, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10720044

RESUMO

Relatively low rates of energy expenditure and fat oxidation predict body weight gain. Weight gain, in turn, is associated with increases in energy expenditure and fat oxidation that may oppose further weight change. In response to experimental weight gain induced by overfeeding, increases in energy expenditure and fat oxidation are overcompensatory, i.e. greater than predicted for the change in body composition. To determine whether such metabolic adaptation occurs in response to spontaneous long term weight change, we conducted a longitudinal study in which 24-h energy expenditure (24-EE) and 24-h respiratory quotient (24-RQ; i.e. fat to carbohydrate oxidation) were repeatedly measured in 102 Pima Indians at baseline and after a mean follow-up of 3.6 +/- 2.7 yr, during which changes in body weight varied widely (-21 to +28 kg). We found that changes in 24-EE and 24-RQ in response to weight change were related to the amount of weight change, even after adjustment for body composition (partial r = 0.23 and -0.30, respectively; both P < 0.05). For a 15-kg weight gain, the increases in 24-EE (+244 Cal/day) and 24-h fat oxidation (+152 Cal/day) were 33 and 53 Cal/day greater than predicted from the cross-sectional relationship between both measures and body weight. Changes in 24-EE and 24-RQ varied substantially among individuals. Thus, on the average, spontaneous long term weight changes are accompanied by small metabolic adaptations in both energy expenditure and fat oxidation. The metabolic responses to weight changes are highly variable among individuals, however.


Assuntos
Adaptação Fisiológica/fisiologia , Peso Corporal/fisiologia , Metabolismo Energético/fisiologia , Gorduras/metabolismo , Adolescente , Adulto , Composição Corporal/fisiologia , Estudos Transversais , Feminino , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Oxirredução , Mecânica Respiratória/fisiologia , Aumento de Peso/fisiologia , Redução de Peso/fisiologia
11.
Ann Neurol ; 47(1): 64-70, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10632102

RESUMO

Weight loss is common among patients with Huntington's disease (HD), although the mechanisms contributing to this phenomenon are not known. We measured 24-hour sedentary energy expenditure (24-hour EE) and sleeping metabolic rate (SMR) in a human respiratory chamber in 17 patients with mild to moderate HD and 17 control subjects matched for age, sex, and body mass index. Total energy expenditure was measured during 7 days in free-living conditions, using the doubly labeled water technique. Body weight, fat mass, and fat-free mass (measured by dual-energy x-ray absorptiometry) were similar in patients with HD and control subjects. Twenty-four-hour EE was 14% higher in HD patients than controls in absolute terms (2,038+/-98 vs 1,784+/-68 kcal/24 hours) and after adjustment for age, sex, fat mass, and fat-free mass (1,998+/-45 vs. 1,824+/-45 kcal/24 hours). In contrast, SMR and total energy expenditure were similar in patients and controls both in absolute terms (1,314+/-38 vs 1,316+/-42 and 2,402+/-102 vs. 2,373+/-98 kcal/24 hours, respectively) and after adjustment. Spontaneous physical activity measured by radar in the chamber and the ratio of 24-hour EE to SMR were significantly higher in HD patients than controls (11.4+/-1.4 vs 6.1+/-0.6% and 1.54+/-0.05 vs 1.36+/-0.03, respectively). In the group as a whole, 24-hour EE/SMR correlated with spontaneous physical activity. Among HD patients, both 24-hour EE/SMR and spontaneous physical activity correlated with the severity of chorea, but SMR and total energy expenditure did not. There were no differences in reported energy intake during 7 days in patients with HD compared with controls. The results of this study indicate that sedentary energy expenditure is higher in patients with HD than in controls in proportion to the severity of the movement disorder. Total free-living energy expenditure is not higher, however, because patients with HD appear to engage in less voluntary physical activity.


Assuntos
Metabolismo Energético , Doença de Huntington/metabolismo , Adulto , Idoso , Ingestão de Alimentos , Exercício Físico/fisiologia , Feminino , Humanos , Doença de Huntington/fisiopatologia , Masculino , Pessoa de Meia-Idade , Fatores de Tempo
12.
Int J Obes Relat Metab Disord ; 23(7): 715-22, 1999 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10454105

RESUMO

BACKGROUND: 24-h energy expenditure (24-EE) and 24-h respiratory quotient (24-RQ) are important measurements in obesity research, but their accurate assessment is limited to few specialized laboratories. OBJECTIVES: 1) To provide comprehensive prediction equations for 24-EE, sleeping metabolic rate (SMR) and 24-RQ, based on a large number of Caucasian and Pima Indian subjects, covering a wide range of body weight and composition, body fat distribution, and age and 2) to test whether Pima Indians have lower metabolic rate and/or higher 24-RQ than Caucasians. SUBJECTS AND METHODS: 916 non-diabetic subjects, aged 31.5 +/- 11.9 y, body weight 90.5 +/- 26.1 kg (mean +/- s.d.), (561 males, 355 females; 416 Caucasians, 500 Pima Indians; 720 with normal (NGT) and 196 with impaired (IGT) glucose tolerance) spent 24 h in a respiratory chamber for measurements of 24-EE, SMR and 24-RQ. Fat-free mass (FFM) and fat mass (FM) were assessed by either hydrodensitometry or DEXA. Waist circumference and waist-to-thigh ratio (WTR) were determined as measures of body fat distribution. RESULTS: In a stepwise multiple regression analysis, FFM, FM, sex, age, WTR, and ethnicity were significant independent determinants of 24-EE (2258 +/- 422 kcal/d), explaining 85% of its variability (24-EE (kcal/d)=696 + 18.9 FFM (kg) + 10.O FM (kg) + 180 male -1.9 age (y) + 7.1 WTR (per decimal) + 44 Pima Indian). SMR (1623 +/- 315kcal/d) was determined (78% of variability) by FFM, FM, sex, age, WTR, and glucose tolerance (SMR (kcal/d) = 443 +/- 14.6 FFM (kg) + 6.9 FM (kg) + 79 male - 1.0 age (y) + 5.8 WTR (per decimal) + 38 IGT), but not by ethnicity. Adjustment for the respective variables reduced the variance in 24-EE from 422 to 162 kcal/d and in SMR from 315 to 146kcal/d. 24-RQ (0.854 +/- 0.026) was determined by waist circumference and energy balance (24-RQ = 0.88429-0.00175 waist circumference (cm) + 0.00004 energy balance (%)), but not by sex, ethnicity or glucose tolerance. With this equation only 13% of the variability in 24-RQ could be explained (residual variance 0.024). Compared to Caucasians, Pima Indians had higher 24-EE, but similar SMR and 24-RQ. CONCLUSIONS: This analysis provides comprehensive prediction equations for 24-EE, SMR and 24-RQ from their major known determinants. It confirms the previous findings that, even after adjustment for body composition, age, sex, ethnicity, and glucose tolerance, there is still considerable variability in energy expenditure and substrate oxidation that may, in part, be genetically determined. In adult Pima Indians, we found no evidence for lower metabolic rate or impaired fat oxidation that could explain the propensity towards obesity in this ethnic group.


Assuntos
Composição Corporal , Metabolismo Energético , Tecido Adiposo/anatomia & histologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Metabolismo Basal , Feminino , Teste de Tolerância a Glucose , Humanos , Indígenas Norte-Americanos , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio , Aumento de Peso , População Branca
13.
Diabetes ; 48(1): 146-9, 1999 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9892236

RESUMO

The recent discovery of uncoupling protein (UCP)-2 and UCP-3, and their high expression in skeletal muscle, has renewed interest in a possible role for these proteins in underlying the variability in energy expenditure and therefore metabolic efficiency. Using reverse transcription-polymerase chain reaction, levels of expression of UCP-2 and long and short forms of UCP-3 were measured in skeletal muscle of 19 nondiabetic, male Pima Indians covering a wide range of body weight. Twenty-four-hour energy expenditure was measured in a respiratory chamber in 16 of these individuals. BMI was negatively correlated with the expression levels of the long (r = -0.53, P = 0.025) and short (r = -0.46, P = 0.047) forms of UCP-3. BMI was not correlated with UCP-2 expression. Metabolic rate during sleep, adjusted for fat-free mass and fat mass, was positively correlated with the long form of UCP-3 (r = 0.69, P = 0.006). These results indicate that UCP-3 may be a determinant of energy expenditure and metabolic efficiency in Pima Indians.


Assuntos
Proteínas de Transporte/metabolismo , Metabolismo Energético/fisiologia , Indígenas Norte-Americanos , Músculo Esquelético/metabolismo , Adulto , Composição Corporal/fisiologia , Índice de Massa Corporal , Humanos , Canais Iônicos , Masculino , Pessoa de Meia-Idade , Proteínas Mitocondriais , Sono/fisiologia , Proteína Desacopladora 3
14.
Am J Clin Nutr ; 68(6): 1223-7, 1998 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9846850

RESUMO

BACKGROUND: This study was designed to determine the effect of chronic spinal cord injury on daily energy expenditure. OBJECTIVE: We hypothesized that both resting and total energy expenditure would be lower in spinal cord-injured (SCI) subjects than in control subjects because of lower sympathetic nervous system activity and reduced levels of physical activity in SCI subjects. DESIGN: Twenty-four-hour energy expenditure (24-h EE), resting metabolic rate (RMR), sleeping metabolic rate, spontaneous physical activity, the thermic effect of food (TEF), and 24-h respiratory quotient were measured by using a respiratory chamber in 10 male SCI subjects (injury ranged from level C6 to L3) and 59 age-matched, noninjured, male control subjects. RESULTS: The 24-h EE was lower in SCI than in control subjects (7824 +/- 305 compared with 9941 +/- 188 kJ, P < 0.01). After adjustment for fat-free mass, fat mass, and age, 24-h EE was still lower (-753 kJ/d, P < 0.01) in SCI than in control subjects. Spontaneous physical activity measured by a radar system was also significantly lower (4.6 +/- 0.6% compared with 6.5 +/- 0.3% of time, P < 0.01) in SCI than in control subjects. In absolute value (7347 +/- 268 compared with 9251 +/- 1326 kJ/d, P < 0.01) or after adjustment for fat-free mass, fat mass, and age (-678 kJ/d, P < 0.01), RMR was also lower in SCI than in control subjects. TEF was significantly lower in SCI than in control subjects (987 +/- 142 compared with 1544 +/- 213 kJ/d, representing 12.9% and 15.9% of total energy intake, respectively, P < 0.05). The sleeping metabolic rate and 24-h respiratory quotient did not differ significantly between groups. CONCLUSIONS: The 24-h EE was significantly lower in SCI than in control subjects. This difference can be explained by the lower levels of physical activity, and lower RMR and TEF values, in SCI subjects.


Assuntos
Metabolismo Energético , Traumatismos da Medula Espinal/metabolismo , Adulto , Metabolismo Basal , Regulação da Temperatura Corporal , Ingestão de Energia , Exercício Físico , Alimentos , Humanos , Masculino , Consumo de Oxigênio , Sono/fisiologia
15.
Diabetologia ; 41(10): 1157-62, 1998 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9794101

RESUMO

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.


Assuntos
Metabolismo Energético , Exercício Físico , Indígenas Norte-Americanos , Obesidade/etiologia , Gravidez em Diabéticas/complicações , Metabolismo Basal , Peso ao Nascer , Glicemia , Composição Corporal , Peso Corporal , Pré-Escolar , Feminino , Idade Gestacional , Humanos , Masculino , Gravidez
16.
J Clin Invest ; 99(4): 592-5, 1997 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-9045859

RESUMO

Leptin, the product of the ob gene, is a hormone secreted by adipocytes that is known to decrease food intake and increase energy expenditure in ob/ob mice. In humans, variants in the OB gene have not been detected and very little is known about the action of leptin on food intake and energy expenditure, although circulating leptin concentrations are positively correlated to body fat stores. The purpose of this study was to assess the relationship between fasting plasma leptin concentrations and energy expenditure in 123 5-yr-old Pima Indian children (67 males/76 females). Body composition was assessed by isotopic water dilution (18O) whereas total energy expenditure (TEE) and resting metabolic rate (RMR) were measured using doubly labeled water and indirect calorimetry, respectively. The physical activity level was calculated as the ratio of TEE:RMR. Plasma leptin concentrations were positively correlated to percent body fat (r = 0.84, P < 0.0001), but were similar in boys and girls after adjusting for percent body fat. Most importantly, we found that, independent of the percentage of body fat, plasma leptin concentrations correlated with TEE (in absolute values, r = 0.37, P < 0.0001, or adjusted for body size r = 0.42; P < 0.0001) and with physical activity level (r = 0.26, P < 0.01), but not RMR. These results suggest that, as in animal models, leptin plays a role in energy expenditure in humans.


Assuntos
Proteínas Sanguíneas/fisiologia , Metabolismo Energético , Esforço Físico , Proteínas/fisiologia , Tecido Adiposo , Composição Corporal , Pré-Escolar , Feminino , Humanos , Leptina , Masculino , Obesidade/sangue
17.
Am J Physiol ; 270(3 Pt 2): R496-504, 1996 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8780213

RESUMO

We compared three independent techniques for measurement of total energy expenditure (TEE) in human subjects: 1) weight-maintaining energy intake (dietTEE), 2) 24-h chamber calorimetry (chamberTEE), and 3) differential elimination rates 2H2O and H(2)18O (isotopeTEE). Twenty-three healthy adult in-patients [19 never obese (NO), 2 obese (OB), and 2 formerly-obese (RO); 9 female, 14 malel] ingested a liquid formula diet (40% of calories as fat, 45% carbohydrate, 15% protein), the volume of which was adjusted until body weight was stable for at least 14 days. Body composition was then determined by hydrodensitometry, isotope dilution, and dual photon beam absorptiometry (DXA). The thermic effect of feeding (TEF) and resting energy expenditure [REE; measured before arising (dietREE) and after arising (chamberREE)] were determined by indirect calorimetry. Non-resting energy expenditure (NREE) was calculated as NREE = TEE - (REE + TEF). Subjects then gained or lost 10% of their body weight and were restudied as described above. All measures of TEE were significantly correlated (dietTEE vs. chamberTEE r2 = 0.75; dietTEE vs. isotopeTEE r2 = 0.88; isotopeTEE vs. chamberTEE r2 = 0.73; P < 0.0001). ChamberTEE (mean +/- SE = 2,107 +/- 64 kcal/day) was approximately 20% lower than either dietTEE (2,536 +/- 94 kcal/day, P < 0.0001) or isotopeTEE (2,564 +/- 83 kcal/day, P < 0.0001). When data were normalized to metabolic mass, weight gain of 10% was associated with significant increases in dietTEE (P < 0.005) and isotopeTEE (P < 0.05) but not chamberTEE; weight loss of 10% was associated with significant reductions in dietTEE (P < 0.005) and isotopeTEE (P < 0.05) but not chamberTEE. We conclude that measures of energy expenditure obtained in a highly controlled environment by caloric titration (dietTEE) or differential excretion rates of 2H2O and H(2)18O (isotopeTEE) are not significantly different and that measurements of TEE obtained in a respiratory chamber (chamberTEE) are significantly lower than dietTEE or isotopeTEE, probably largely due to limitations on physical activity in the chamber.


Assuntos
Composição Corporal , Metabolismo Energético , Adulto , Dieta , Feminino , Humanos , Masculino
18.
Am J Clin Nutr ; 62(5): 911-7, 1995 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-7572735

RESUMO

Epidemiologic studies consistently report associations between obesity and dietary fat but not total energy intake. We measured ad libitum food intake in a laboratory setting and evaluated its relation to body weight and composition, energy expenditure, and macronutrient utilization in 28 women of Pima-Papago heritage (aged 27 +/- 7 y, 85.3 +/- 19.0 kg, 44 +/- 6% body fat; means +/- SD). All women were studied during the follicular phase of the menstrual cycle. After a 4-d weight-maintenance period, the volunteers selected their food for 5 d from computerized vending machines offering a variety of familiar and preferred foods, ie, a "cafeteria diet". Twenty-four-hour energy expenditure and substrate oxidation were measured in a respiratory chamber on the 4th d o weight maintenance and the 5th d of ad libitum intake. Average ad libitum intake was 13,732 +/- 4238 kJ/d (11 +/- 1% protein, 40 +/- 1% fat, 49 +/- 4% carbohydrate), ie, moderate overeating by 27 +/- 37% above weight maintenance requirements (range: -27% to 124%). Percent body fat correlated with daily energy intake (r = 0.53, P < 0.01), the degree of overeating (r = 0.41, P < 0.05), and the selection of a diet higher in fat and lower in carbohydrate (r = 0.70 and r = -0.63, respectively, P < 0.001). Excess carbohydrate intake caused an increase in carbohydrate oxidation (r = 0.51, P < 0.01), whereas excess fat intake resulted in a decrease in fat oxidation (r = -0.53, P < 0.01) and thus a positive fat balance of 85 +/- 65 g/d. The positive relations among degrees of obesity, dietary fat intake and overeating, and the fact that dietary fat does not induce fat oxidation, support the hypothesis that dietary fat promotes obesity in women.


Assuntos
Composição Corporal/fisiologia , Dieta , Ingestão de Energia/fisiologia , Metabolismo Energético/fisiologia , Indígenas Norte-Americanos , Obesidade/fisiopatologia , Adulto , Carboidratos da Dieta/administração & dosagem , Carboidratos da Dieta/metabolismo , Gorduras na Dieta/administração & dosagem , Gorduras na Dieta/metabolismo , Proteínas Alimentares/administração & dosagem , Proteínas Alimentares/metabolismo , Comportamento Alimentar/etnologia , Comportamento Alimentar/fisiologia , Feminino , Preferências Alimentares/etnologia , Humanos , Pessoa de Meia-Idade , Obesidade/etnologia , Oxirredução , Consumo de Oxigênio
19.
Int J Obes Relat Metab Disord ; 19(5): 331-7, 1995 May.
Artigo em Inglês | MEDLINE | ID: mdl-7647825

RESUMO

OBJECTIVE: To investigate the relationship between obesity and ad libitum food intake (quantity and composition) and to assess the impact of ad libitum food intake on energy expenditure and macronutrient oxidation. DESIGN: Male volunteers were first fed a weight maintaining diet for at least 4 days before selecting their food for the next 5 days from two computerized vending machines offering a variety of familiar, palatable foods. 24-h energy expenditure (24EE) and substrate oxidation were measured in a respiratory chamber on the last day of each weight maintenance and ad libitum intake periods. SETTING: Ten day admission on a metabolic research ward. SUBJECTS: Thirty-four non-diabetic Pima Indian males covering a wide range of body weight and body composition (30 +/- 8 y, 102.1 +/- 30.2 kg, 34 +/- 9% body fat, mean +/- s.d.). RESULTS: Weight maintenance requirements averaged 2913 +/- 342 kcal/d. Energy intake during the ad libitum period increased to 4550 +/- 921 kcal/d (12 +/- 1% protein, 40 +/- 4% fat, 48 +/- 4% carbohydrate) i.e., a spontaneous overeating by 54 +/- 32% above weight maintenance requirement, resulting in a 0.9 +/- 1.0 kg body weight gain. Neither the composition of the selected diet nor the degree of overeating was associated with physical characteristics, such as body weight and body composition. When compared with baseline, spontaneous overeating on day 5 was associated with a 396 +/- 233 kcal/d increase in 24EE, a 607 +/- 503 kcal/d increase in carbohydrate oxidation, a 214 +/- 392 kcal/d decreased in lipid oxidation (P < 0.01), and no change in protein oxidation. Increased carbohydrate oxidation correlated with the excess carbohydrate intake (r = 0.69, P = 0.0001) accounting for 68 +/- 13% (mean +/- s.e.e.) of the excess, whereas excess fat intake was not oxidized. CONCLUSION: In response to spontaneous overfeeding on a mixed 'cafeteria diet', excess carbohydrate intake is oxidized, suggesting a physiological control of carbohydrate stores, whereas excess fat intake is channeled toward fat stores. None of the observed changes were related to indices of obesity.


Assuntos
Ritmo Circadiano/fisiologia , Ingestão de Alimentos/fisiologia , Metabolismo Energético/fisiologia , Comportamento Alimentar/fisiologia , Adulto , Composição Corporal/fisiologia , Peso Corporal/fisiologia , Carboidratos da Dieta/metabolismo , Gorduras na Dieta/metabolismo , Proteínas Alimentares/metabolismo , Humanos , Indígenas Norte-Americanos , Masculino , Pessoa de Meia-Idade , Obesidade/etnologia , Obesidade/fisiopatologia , Oxirredução
20.
Med Sci Sports Exerc ; 27(3): 347-54, 1995 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-7752861

RESUMO

The 24-h energy expenditure (24-h EE), resting EE (REE), sleeping EE (SEE), and spontaneous physical activity (SPA) were compared between six male endurance athletes whose reported energy intake was low (LOW) and did not match that theoretically required for weight maintenance and four whose reported energy intake appeared adequate (ADQ) and matched their estimated EE. Groups did not differ in age, body weight, fat-free mass, and daily EE estimated from activity records. The LOW athletes reported an energy intake 6338 +/- 2164 kJ.d-1 less than estimated EE. The 24-h EE, REE, SEE, and SPA of the LOW athletes were significantly lower than the ADQ athletes (862, 523, 770 kJ.d-1, and 43 min.d-1, respectively). Using all subjects, there was a significant positive correlation between REE and free thyroxine (FT4) (r = 0.82) and SEE and FT4 (r = 0.66). Thus, part of the LOW athlete's ability to maintain body weight on a seemingly low energy intake appears due to a lower daily sedentary EE.


Assuntos
Ingestão de Energia , Metabolismo Energético/fisiologia , Resistência Física/fisiologia , Esportes/fisiologia , Atividades Cotidianas , Adulto , Metabolismo Basal/fisiologia , Composição Corporal , Constituição Corporal , Peso Corporal , Dieta , Frequência Cardíaca/fisiologia , Humanos , Masculino , Consumo de Oxigênio/fisiologia , Sono/fisiologia , Tiroxina/sangue , Tri-Iodotironina/sangue
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