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The physiologic and metabolic effects of chronic consumption of energy below recommended levels on constant-load exercise was studied in women age 19-24 years. Ten controls (average caloric intake ~ 35 kcal/kg body weight) and 10 subjects with suboptimal energy intake (average caloric intake - 25 kcal/kg body weight) were matched for age, exercise caloric expenditure and percentage of HB-predicted RMR. Subjects (n=20) completed a maximal incremental cycle ergometer test and a 30-minute cycle ergometer test at 75 % of peak oxygen consumption. Although both groups presented a significant increase in ventilation (VE) over time of exercise, the rate of change in VE and end-exercise VE value was significantly greater, F (1 J 18) = 5.63, P < .05, for the suboptimal energy intake group than for the controls. Although not statistically significant (p = 0.454), heart rate (HR) tended to be continuously higher for the suboptimal energy intake group than the control group during the constant-load cycle test. Peripheral ratings of perceived exertion (RPE-L) also tended to be higher for the suboptimal energy intake group at the end of constant-load exercise, however, not significantly (p = 0.072). Two subjects in the suboptimal energy intake group failed to complete the 30-minute submaximal constant-load cycle test; one completed 15 minutes and the other 20 minutes. All subjects in the control group completed the entire submaximal constant-load test (30 minutes). These results suggest that women with chronic suboptimal energy intake have increased difficulty tolerating moderate intensity exercise for 30 minutes (an intensity and duration that mimics a typical exercise session). / Master of Science

Mudanças no hábito alimentar têm sido descritas como prováveis causas da obesidade. Estudos mostram que o peso depende do balanço energético definido pela relação entre a energia ingerida e o gasto energético. Sugere-se que o padrão alimentar, levando em consideração a freqüência de refeições e sua distribuição durante o dia, possa estar relacionado com a obesidade. Um efetivo programa de perda de peso tem como objetivo a perda do excesso da gordura corporal e a manutenção da massa livre de gordura apropriada para manutenção da saúde. O cortisol é um dos principais hormônios secretados pelo córtex supra-renal com ação predominante no metabolismo intermediário, incluindo a regulação das proteínas, carboidratos, lipídeos e ácidos nucléicos.O presente estudo teve como objetivos determinar se a ingestão alimentar hipocalórica em pacientes obesas grau III, feita exclusivamente no período das 9:00 às 11:00 h em contraposição à mesma dieta oferecida das 18:00 às 20:00 h, é capaz de alterar a perda de peso, a composição corporal, o ritmo de cortisol, o gasto energético e o balanço nitrogenado. As pacientes foram internadas na Unidade Metabólica da Divisão de Nutrologia do Departamento de Clínica Médica do Hospital das Clínicas de Ribeirão Preto USP durante um período de 64 dias, sendo divididos em 3 internações de 18 dias. Na 1ª fase receberam dieta fracionada em 5 refeições /dia, considerada controle. Na 2ª fase, receberam a mesma dieta, no período das 9:00 às 11:00 h. E na 3ª fase receberam, também, a mesma dieta no período das 18:00 às 20:00 h. Entre uma internação e outra, as pacientes tiveram alta hospitalar por 5 dias, recebendo dieta domiciliar usual. Durante cada fase realizou-se dosagem de nitrogênio urinário e de cortisol salivar. Além disto, as pacientes foram submetidas à avaliação nutricional incluindo: antropometria, bioimpedância e calorimetria indireta. O cortisol salivar obedeceu ao mesmo ritmo nas 3 fases, tanto no 1º quanto no 18º dias de internação, apresentando o pico máximo às 8:00 h, diminuindo progressivamente até atingir o nadir às 21:00 h. Não houve alteração no ritmo do cortisol quando se alterou o horário da alimentação. Houve uma diminuição significativa (p< 0,05) para todos os parâmetros antropométricos, exceto para o índice cintura/quadril durante as três fases, não havendo diferença entre as 3 fases. Houve, nas 3 internações, uma diminuição significativa tanto na quantidade de nitrogênio ingerido quanto na quantidade de nitrogênio excretado a partir do 4º dia de internação. No 10º dia de internação, o balanço nitrogenado estava negativo nas 3 fases da dieta. Não houve diferença entre as fases para ingestão, excreção ou balanço nitrogenado. Mudanças no padrão do horário da ingestão alimentar por períodos de 18 dias não foram estímulo suficiente para provocar diferentes alterações de peso, da composição corporal, da ritmicidade e níveis de produção de cortisol, da taxa metabólica de repouso e balanço nitrogenado em mulheres grau III. / Changes in dietary habits have been implicated as potential causes of obesity. Studies have suggested that weight depends on the energetic balance, which is the relation between energy intake and energy expenditure. Dietary behavior, specially eating frequency and temporal distribution of eating events during the day, may be related to obesity. An effective weight loss program should reduce body fat and preserve lean body mass. Cortisol is an important corticosteroid produced by the adrenal. It exerts metabolic effects on intermediary metabolism, regulating protein, carbohydrates, lipids and nucleic acids metabolism. The present studys goals were: compare differences in weight loss, body composition, energy expenditure and nitrogen balance using hypo caloric diet offered in two different time intervals, first from 9:00 to 11:00, second from 18:00 to 20:00; determinate if there is difference on urinary nitrogen when food is offered on different time intervals, comparing with salivary cortisol levels, and show salivary cortisol secretion rhythm of obese females undergoing hypo caloric diet in different day times. The patients were under hospital regimen in the Metabolic Unit of the Nutrology Division of the Internal Medicine Department of the HCFMRP USP for a 64 days period, divided in 3 periods of 18 days each. On phase 1, the patients received food five times a day. On phase 2, they received the same diet, but the meals were between 09:00 and 11:00. On phase 3, the same diet was offered between 18:00 and 20:00. After each 18 day period, patients went home for a 5 day wash-out period, eating their regular home food and respecting their usual dietary behavior. On each phase urinary nitrogen and salivary cortisol were measured. Also a nutritional evaluation, including anthropometry, bioimpedance and indirect calorimetry were done. There were a reduction (p< 0,05) in all parameters, except the Waist/ Hip Ratio during all phases, but there were no difference between the phases. On the 3 phases there were a reduction on both, nitrogen intake and excretion. After the 10th in hospital day, nitrogen balance was negative on the 3 phases. There are no differences on nitrogen intake, excretion or balance between the 3 phases of food intake. Salivary cortisol followed the same rhythm on all 3 phases, both on the 1st and on the 18th in hospital days, having the peak salivary level at 08:00 h and the nadir level at 21:00 h. Changing meal times for 18 days did not change salivary cortisol circadian rhythm and did not promote changes in weight loss, body composition and rest energy expenditure in grade III obese females.

A contribuição genética para o desenvolvimento da obesidade precisa ser esclarecida em intervenções para perda de peso, como é o caso da cirurgia bariátrica. Portanto, a análise da expressão gênica relacionada ao gasto energético e posterior associação com a taxa metabólica de repouso pode elucidar o entendimento de fatores genéticos que contribuem para a obesidade. Além disso, as informações genéticas expressas em determinados indivíduos, podem ajudar a esclarecer mecanismos relacionados à regulação energética e oxidação de substratos. Assim, o objetivo do presente trabalho foi verificar a expressão dos genes ADRB3, UCPs, PLIN1, PPARG2, em tecido adiposo subcutâneo abdominal e associar com medidas da taxa metabólica de repouso em indivíduos obesos grau III antes e após cirurgia bariátrica. A amostra foi composta por 13 mulheres com obesidade antes e após 6 meses de cirurgia bariátrica pela técnica de derivação gástrica em Y de Roux e 10 mulheres eutróficas. Tratou-se de um estudo longitudinal, no qual foram coletadas medidas antropométricas de peso, estatura, índice de massa corporaI, circunferência abdominal, composição corporal (massa corporal magra e massa gorda) pela bioimpedância elétrica, calorimetria indireta para mensurar a taxa metabólica de repouso e análise de expressão gênica pela técnica de PCR em tempo real. Foram observadas diferenças nas variáveis de peso, índice de massa corporal, circunferência abdominal, massa corporal magra, massa gorda e taxa metabólica de repouso entre os grupos do estudo. Houve diminuição dos valores absolutos da taxa metabólica de repouso (2.094±275 vs 1.863±210kcal, p=0,01), porém quando ajustada pelo peso observou-se aumento (17,7±2,1 vs 20,4±2,1kcal/kg p=0,01). A massa corporal magra no momento pós operatório exerceu influência de 29% na taxa metabólica de repouso por quilograma de peso, sendo que houve correlação positiva entre as duas variáveis (r=0,63, p=0,02). A expressão do gene UCP2 apresentou diferença entre os dois momentos do estudo (p=0,01). Houve influência dos genes UCP2 e PLIN1 na taxa metabólica de repouso por quilograma de peso no período pré operatório. O percentual de perda de peso foi influenciado pela expressão dos genes UCP2 e PLIN1 no período pré operatório. Conclui-se que as modificações proporcionadas pela cirurgia bariátrica aumentam a expressão dos genes e gasto energético de mulheres com obesidade grau III. / The contribution of genetic to the development of obesity need to be established accurately interventions for weight loss, as in the case of bariatric surgery. Therefore, the analysis of gene expression related to energy expenditure and subsequent association with the resting metabolic rate can elucidate the understanding of genetic factors that contribute to obesity. Furthermore, the genetic information expressed in certain individuals may help clarify regulatory mechanisms related to energy and substrate oxidation. The objective was to investigate the expression of genes ADRB3, UCPs, PLIN1 and PPARG2 in abdominal subcutaneous adipose tissue and associate it with measures of resting metabolic rate in grade III obese patients before and after bariatric surgery. The sample consisted of 13 obese women before and 6 months after bariatric surgery (gastric bypass Roux-Y technique) and 10 healthy women. This was a longitudinal study in which anthropometric measurements of weight were collected, height, body mass index, waist circumference, body composition (lean body mass and fat mass) by bioelectrical impedance, indirect calorimetry to measure the resting metabolic rate and gene expression was analysed by PCR real time. Differences in body weight, body mass index, waist circumference, lean body mass, fat mass and resting metabolic rate between the study groups. There was a decrease of the absolute values of the resting metabolic rate (2.094±275 vs 1863±210kcal, p=0,01), but when adjusted for body weight an increase was observed (17,7±2,1 vs 20,4±2,1kcal/kg p=0,01). Lean body mass in the post operative period influenced 29% in resting metabolic rate per kilogram of weight, and there was a positive correlation between resting metabolic rate and lean body mass (r=0,63, p=0,02). The expression of UCP2 gene was different between the two sample points (p=0,01). There was influence of UCP2 and PLIN1 genes in resting metabolic rate per kilogram of weight in the preoperative period. The percentage of weight loss was influenced by the UCP2 gene and PLIN1 preoperative period. We conclude that the modifications provided by bariatric surgery increase the gene expression and energy expenditure women with morbid obesity.

PURPOSE: Pregnancy is a physically impactful process in a woman’s life. During this time, a woman will gain weight and research has shown that many women will retain some extra weight after delivery. Because of this, recovery in the postpartum period is pivotal to avoiding the implications of weight retention. The postpartum period is vastly understudied in both the research and medical communities and this gap between pregnancy and postpartum research needs to be bridged. Therefore, the purpose of this study was to investigate metabolic changes from pregnancy to postpartum and to study how factors such as sleep and breastfeeding can impact metabolic values in the postpartum period. METHODS: Women participated in a pregnancy study visit at 32-34 weeks of gestation (n = 25) and attended two subsequent visits at 4-6 months (n = 25) and 12-13 months postpartum (n = 16). At these visits, the women had a baseline blood draw and baseline metabolic measurements taken via indirect calorimetry. At the pregnancy visit, participants completed a demographic survey and a dietary questionnaire (DHQ-II). At the postpartum visits, they completed the same surveys, along with validated sleep and breastfeeding surveys. RESULTS: Absolute resting metabolic rate (RMR) was significantly higher during pregnancy than at 4-6 months postpartum and 12-13 months postpartum (p < 0.001 and p = 0.001, respectively). Accounting for body weight, relative RMR was significantly higher during pregnancy than at 4-6 months postpartum. With regard to sleep, women deemed to be “good sleepers” had a significantly higher relative RMR than those who were deemed “poor sleepers” (23.6 ± 2.5 vs 20.8 ± 2.3, p = 0.009). With regard to breastfeeding, women who breastfed had a relative RMR than the women who did not breastfeed (22.8 ± 2.6 vs 20.4 ± 2.3, p = 0.046). CONCLUSIONS: There are hypermetabolic changes that take place during pregnancy. These values seem to decrease into the postpartum period. Women who demonstrate an improved sleep quality and who opt to breastfeed tend to have improved metabolic responses. This could help combat the struggle with postpartum weight retention that some women face.

Energy intake (EI) and energy expenditure (EE) across the menstrual cycle (MC), while considering body adiposity, have not been previously evaluated in the same individuals. This study mainly examined the variations in energy balance (EB) across MC. Seventeen women (Body fat-DXA:28.5%) participated in three identical sessions during distinct phases of the MC: Early-follicular, Late-follicular/ovulation and Mid-luteal (confirmed by basal temperature and sex-steroid hormones). EI, resting metabolic rate (RMR), physical-activity EE (PAEE), severity of PMS, leptin and relative-reinforcing value (RRV) of preferred foods were measured during each phase. No differences in body fat, EI, RMR, PAEE, leptin and RRV of food were noted across MC. Trends were noted in preferred snack (p=0.06) and combined snack/fruit (p=0.06) intakes, while differences were noted in severity of PMS (p<0.05) across phases. Changes in EB across the MC were not noted. PMS was more severe, and preferred snack and combined snack/fruit intakes were slightly higher during mid-luteal phase.

Energy intake (EI) and energy expenditure (EE) across the menstrual cycle (MC), while considering body adiposity, have not been previously evaluated in the same individuals. This study mainly examined the variations in energy balance (EB) across MC. Seventeen women (Body fat-DXA:28.5%) participated in three identical sessions during distinct phases of the MC: Early-follicular, Late-follicular/ovulation and Mid-luteal (confirmed by basal temperature and sex-steroid hormones). EI, resting metabolic rate (RMR), physical-activity EE (PAEE), severity of PMS, leptin and relative-reinforcing value (RRV) of preferred foods were measured during each phase. No differences in body fat, EI, RMR, PAEE, leptin and RRV of food were noted across MC. Trends were noted in preferred snack (p=0.06) and combined snack/fruit (p=0.06) intakes, while differences were noted in severity of PMS (p<0.05) across phases. Changes in EB across the MC were not noted. PMS was more severe, and preferred snack and combined snack/fruit intakes were slightly higher during mid-luteal phase.

Obesity is affecting an increasingly larger proportion of adolescents in the world, and this can be attributed to low resting metabolic rate (RMR) as well as reduced physical activity (PA) levels. Little is known about objectively determined habitual PA and RMR in 16 year old African adolescents. The purpose of this study is twofold. Firstly, to determine the objectively measured PA status of adolescents and secondly, to determine the relationship that exists between RMR and PA in 16 year old adolescents. Two hundred and twenty six (226) adolescents aged sixteen (16) wore the Actiheart® monitor, combined accelerometry and heart rate for seven (7) consecutive days. Six high schools were recruited to take part in the study: two from town (high socio-economic status) and four from the township (low socio-economic status) of the Potchefstroom area of the North West Province of South Africa. Times spent in moderate to vigorous physical activity, physical activity counts per minute (CPM), total energy expenditure (TEE), active energy expenditure (AEE) and physical activity levels (PAL) were assessed using the Actiheart®. The participants’ RMR was measured by indirect calorimetry using the Fitmate Pro (Cosmed, Italy). All data analyses were performed with the SPSS Version 20 software (IBM SPSS, II). The descriptive statistics (mean and standard deviations) as well as independent t-tests and Mann-Whitney U test were performed to determine differences between ethnicity and genders and to calculate practical significance. A Type I error rate of p ≤ 0.05 was used for statistical significance. To investigate the relationship between RMR and physical activity regression analysis was performed with adjustment for gender, race and fat free mass. Results: Significantly higher PAL (1.57 ± 0.15) were determined in girls compared to boys (PAL = 1.41 ± 0.10). Black adolescents indicated significant higher PAL (1.53 ± 0.14) compared to white adolescents (1.45 ± 0.16). On average, regardless of race or gender, the participants were more active on weekdays than weekends. The current study shows that girls spent more minutes/day in moderate to vigorous physical activity (MVPA) than the boys. The results show that 16.4% of the study sample was either overweight or obese. After adjustment for gender, ethnicity and FFM, linear regression between RMR and moderate-to-vigorous PA yielded an r2 = 0.46 (p ˂ 0.05.) Conclusion: Objectively determined PA of adolescents in South Africa indicates that only one third of adolescents are meeting the recommended 60 minutes of daily MVPA. Gender and race specific interventions are needed to increase habitual physical activity levels in adolescents. Given the fact that the studied sample did not meet recommended daily physical activity and the adverse effect of inactivity and chronic diseases of life style, urgent strategies to inculcate the culture of regular physical activity as a preventative measure of chronic diseases of life style are needed. Behaviour that is carried on into adulthood is established during adolescence. Civic health efforts should focus on encouraging adolescent involvement in regular moderate-to-vigorous PA, which will subsequently increase RMR and lower the risk of the development of non-communicable chronic diseases such as obesity. Further local research is needed to confirm the association between RMR and PA in the local population. / Thesis (MSc (Biokinetics))--North-West University, Potchefstroom Campus, 2013.

Obesity is affecting an increasingly larger proportion of adolescents in the world, and this can be attributed to low resting metabolic rate (RMR) as well as reduced physical activity (PA) levels. Little is known about objectively determined habitual PA and RMR in 16 year old African adolescents. The purpose of this study is twofold. Firstly, to determine the objectively measured PA status of adolescents and secondly, to determine the relationship that exists between RMR and PA in 16 year old adolescents. Two hundred and twenty six (226) adolescents aged sixteen (16) wore the Actiheart® monitor, combined accelerometry and heart rate for seven (7) consecutive days. Six high schools were recruited to take part in the study: two from town (high socio-economic status) and four from the township (low socio-economic status) of the Potchefstroom area of the North West Province of South Africa. Times spent in moderate to vigorous physical activity, physical activity counts per minute (CPM), total energy expenditure (TEE), active energy expenditure (AEE) and physical activity levels (PAL) were assessed using the Actiheart®. The participants’ RMR was measured by indirect calorimetry using the Fitmate Pro (Cosmed, Italy). All data analyses were performed with the SPSS Version 20 software (IBM SPSS, II). The descriptive statistics (mean and standard deviations) as well as independent t-tests and Mann-Whitney U test were performed to determine differences between ethnicity and genders and to calculate practical significance. A Type I error rate of p ≤ 0.05 was used for statistical significance. To investigate the relationship between RMR and physical activity regression analysis was performed with adjustment for gender, race and fat free mass. Results: Significantly higher PAL (1.57 ± 0.15) were determined in girls compared to boys (PAL = 1.41 ± 0.10). Black adolescents indicated significant higher PAL (1.53 ± 0.14) compared to white adolescents (1.45 ± 0.16). On average, regardless of race or gender, the participants were more active on weekdays than weekends. The current study shows that girls spent more minutes/day in moderate to vigorous physical activity (MVPA) than the boys. The results show that 16.4% of the study sample was either overweight or obese. After adjustment for gender, ethnicity and FFM, linear regression between RMR and moderate-to-vigorous PA yielded an r2 = 0.46 (p ˂ 0.05.) Conclusion: Objectively determined PA of adolescents in South Africa indicates that only one third of adolescents are meeting the recommended 60 minutes of daily MVPA. Gender and race specific interventions are needed to increase habitual physical activity levels in adolescents. Given the fact that the studied sample did not meet recommended daily physical activity and the adverse effect of inactivity and chronic diseases of life style, urgent strategies to inculcate the culture of regular physical activity as a preventative measure of chronic diseases of life style are needed. Behaviour that is carried on into adulthood is established during adolescence. Civic health efforts should focus on encouraging adolescent involvement in regular moderate-to-vigorous PA, which will subsequently increase RMR and lower the risk of the development of non-communicable chronic diseases such as obesity. Further local research is needed to confirm the association between RMR and PA in the local population. / Thesis (MSc (Biokinetics))--North-West University, Potchefstroom Campus, 2013.