To investigate changes in body composition and the validity of the leg-to-leg bioimpedance (LTL) ... more To investigate changes in body composition and the validity of the leg-to-leg bioimpedance (LTL) method to measure body fat during active weight loss (WL) and weight regain (WR). Longitudinal, 12-week weight loss intervention (3.3-3.8 MJ/day) and subsequent follow-up at 1 year. Fifty-eight adult women aged between 24 and 65 years (mean age: 46.8+/-8.9 years) and with a body mass index (BMI) > or =25 kg/m(2) (mean BMI: 31.6+/-2.5 kg/m(2), range=26.0-48.2 kg/m(2)) participated in the study. Fat mass (FM) was measured at baseline, 12 weeks, 24 weeks and 52 weeks using three- and four-compartment (4-C) models, air displacement plethysmography (ADP), deuterium dilution - total body water (TBW), dual-energy X-ray absorptiometry (DXA), skinfold thickness (SFT), tetrapolar bioelectrical impedance analysis (T-BIA) and LTL. At the end of the weight loss programme, subjects lost 9.9+/-3.5 kg weight (P<0.001) and 7.6+/-0.5 kg fat (P<0.001) but after 1 year they had regained 4.9+/-3.7 k...
Although inorganic nitrate and beetroot juice supplementation are associated with decreased systo... more Although inorganic nitrate and beetroot juice supplementation are associated with decreased systolic blood pressure (BP), these results have primarily been obtained from short-term trials that focused on healthy young adults. Therefore, we hypothesized that oral supplementation of beetroot juice concentrate would decrease systolic BP in overweight older participants but that the decline in BP would not be sustained after a 1-week interruption of the beetroot juice supplementation. For 3 weeks, 24 participants were randomized to either the beetroot juice concentrate or blackcurrant juice group, with a 1-week postsupplementation phase (week 4). Changes in systolic and diastolic BP were assessed during the supplementation and postsupplementation phases. Blood pressure was measured using 3 different methods: (1) resting clinic BP, (2) 24-hour ambulatory BP monitoring, and (3) home monitoring of daily resting BP. The first 2 methods were applied at baseline and after weeks 3 and 4. Daily...
Nutrition, Metabolism and Cardiovascular Diseases, 2014
Whereas adult weight or body mass index (BMI) are directly associated with blood pressure (BP), b... more Whereas adult weight or body mass index (BMI) are directly associated with blood pressure (BP), birth weight is inversely associated with BP. The scenario for height is more complex, as both tall and short stature have been associated with higher BP. We used a theoretical model treating sitting height (SH) and tissue masses (fat mass, lean mass) as components of metabolic load, and leg length (LL) as a marker of homeostatic metabolic capacity. We predicted that decreased capacity and increased load would be independently associated with increased BP.. Anthropometry, body composition (bio-electrical impedance analysis) and BP were measured in 601 adults (228 male) aged 20-91 years from three hill villages in southern Italy. Multiple regression analysis was used to investigate associations of body composition and anthropometry with BP. Adjusting for age, systolic BP (SBP) was associated with lean mass in males, and with adiposity in females, whereas diastolic BP (DBP) was associated with fat mass in both sexes. Associations of LL and SH with BP were in opposite directions. LL was inversely associated with SBP and DBP in males, with a similar trend evident in females. SH was directly associated with SBP and DBP in females, and with DBP in males. Consistent with our theoretical model, metabolic load is associated with increased BP, though differently between the sexes, whereas metabolic capacity is independently associated with lower BP. Our findings suggest that early growth improves hemodynamic tolerance of high metabolic load in adulthood..
Abnormal body compositions such as high adiposity (HA), low muscle mass (LM), or a combination of... more Abnormal body compositions such as high adiposity (HA), low muscle mass (LM), or a combination of the 2 [high adiposity with low muscle mass (HA-LM)] are relevant phenotypes, but data on their prevalence and impact on health are still limited. This is largely because of a lack of a consensus definition for these conditions. Of particular interest is the HA-LM phenotype, also termed &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;sarcopenic obesity,&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; which may confer greater health risk. We propose a new approach for operationalizing abnormal body-composition phenotypes in a representative adult population. Whole-body dual-energy X-ray absorptiometry data obtained from the 1999-2004 NHANES were analyzed for 13,236 subjects aged ≥18 y (maximum weight and height of 136 kg and 1.96 m, respectively). Sex- and body mass index (BMI)-specific decile groups of appendicular skeletal muscle index (ASMI; kg/m(2)) and fat mass index (FMI; kg/m(2)) were developed. Cutoffs for HA and LM were incorporated into a diagnostic framework to characterize 4 specific body-composition phenotypes-low adiposity with high muscle mass, high adiposity with high muscle mass, low adiposity with low muscle mass, and HA-LM-and a subclassification of the phenotypes into classes I, II, and III. Abnormal phenotypes were prevalent across the age spectrum and BMI categories. The association between ASMI or FMI and age was modified by sex and BMI. The prevalence of HA-LM in the whole sample was 10.3% in women and 15.2% in men. The prevalence of all subclasses of HA-LM in obese women and men was 14.7% and 22.9%, respectively. HA-LM class III was more prevalent in obese men (2.3%) than in obese women (0.3%). We developed sex- and BMI-specific reference curves to harmonize the classification of body-composition phenotypes. The application of this classification will be particularly useful in the identification of cases of sarcopenic obesity. The association of these phenotypes with metabolic deregulation and increased disease risk awaits verification.
High adiposity in middle age is associated with higher dementia risk. The association between wei... more High adiposity in middle age is associated with higher dementia risk. The association between weight loss and cognitive function in older adults is still controversial. A meta-analysis was undertaken to estimate the effectiveness of intentional weight loss on cognitive function in overweight and obese adults. A structured strategy was used to search randomized and non-randomized studies reporting the effect of intentional and significant weight loss on cognitive function in overweight and obese subjects. Information on study design, age, nutritional status, weight-loss strategy, weight lost and cognitive testing was extracted. A random-effect meta-analysis was conducted to obtain summary effect estimates for memory and attention-executive domains. Twelve studies met inclusion criteria. Seven were randomized trials and the remaining five included a control group. A low-order significant effect was found for an improvement in cognitive performance with weight loss in memory (effect size 0.13, 95% CI 0.00-0.26, P=0.04) and attention/executive functioning (effect size 0.14, 95% CI 0.01-0.27, P&lt;0.001). Studies were heterogeneous in study design, sample selection, weight-loss intervention and assessment of cognitive function. Weight loss appears to be associated with low-order improvements in executive/attention functioning and memory in obese but not in overweight individuals.
The Thrifty Gene hypothesis theorizes that during evolution a set of genes has been selected to e... more The Thrifty Gene hypothesis theorizes that during evolution a set of genes has been selected to ensure survival in environments with limited food supply and marked seasonality. Contemporary environments have predictable and unlimited food availability, an attenuated seasonality due to artificial lighting, indoor heating during the winter and air conditioning during the summer, and promote sedentariness and overeating. In this setting the thrifty genes are constantly activated to enhance energy storage. Psychosocial stress and sleep deprivation are other features of modern societies. Stress-induced hypercortisolemia in the setting of unlimited food supply promotes adiposity. Modern man is becoming obese because these ancient mechanisms are efficiently promoting a positive energy balance. We propose that in today&#39;s plentifully provisioned societies, where sedentariness and mental stress have become typical traits, chronic activation of the neuroendocrine systems may contribute to the increased prevalence of obesity. We suggest that some of the yet unidentified thrifty genes may be linked to highly conserved energy sensing mechanisms (AMP kinase, mTOR kinase). These hypotheses are testable. Rural societies that are becoming rapidly industrialized and are witnessing a dramatic increase in obesity may provide a historical opportunity to conduct epidemiological studies of the thrifty genotype. In experimental settings, the effects of various forms of psychosocial stress in increasing metabolic efficiency and gene expression can be further tested.
Stable isotopic methods are considered the &quot;gold standard&quot; for the measurement ... more Stable isotopic methods are considered the &quot;gold standard&quot; for the measurement of rates of in vivo NO production. However, values reported for healthy human individuals differ by more than 1 order of magnitude. The reason for the apparent variability in NO production is unclear. The primary aim of this review was to evaluate and compare the rates of in vivo NO production in health and disease using stable isotope methods. Articles were retrieved using the PubMed electronic database. Information on concentrations, isotopic enrichments of fluxes, and conversion rates of molecules involved in the NO metabolic pathway was extracted from selected articles; 35 articles were included in the final analysis. Three protocols were identified, including the arginine-citrulline, the arginine-nitrate, and the oxygen-nitrate protocols. The arginine-citrulline protocol showed a wider variability compared to the arginine-nitrate and oxygen-nitrate protocols. The direction of the association between disease state and rate of NO production was essentially determined by the etiopathogenesis of the disorder (inflammatory, metabolic, vascular). Considerable variation in methodologies used to assess whole-body NO synthesis in humans exists. The precision of several aspects of the techniques and the validity of some assumptions made remain unknown, and there is a paucity of information about physiological rates of NO production from childhood over adolescence to old age.
Ethnic differences in the association between body mass index (BMI) and body fat suggest that bod... more Ethnic differences in the association between body mass index (BMI) and body fat suggest that body composition varies across ethnic groups. To investigate the association between impedance index - a measure of tissue resistivity - and BMI in adults of different ethnic groups (Asian Indians, West Africans and White Caucasians) living in their native countries. Male (n=329) and female (n=277) adult subjects (18-50 years) living in urban areas in the UK, The Gambia and Pakistan were studied. Body weight and height were measured and BMI calculated. The same leg-to-leg bioimpedance instrument was used in each study and impedance index (height(2) (cm)/impedance (Omega)) used as measure of tissue resistivity. In women, Asian Indians and West Africans had a significantly greater increase in impedance index per unit increase in BMI compared with white Caucasians (P&amp;amp;lt;0.001). In men, Asian Indians had a significantly lower impedance index compared with West Africans and white Caucasians (P&amp;amp;lt;0.001). Different ethnic groups may have different tissue resistivity for the same BMI indicative of systematic differences in body composition.
Eating and Weight Disorders - Studies on Anorexia, Bulimia and Obesity, 2006
We investigated the attitudinal and perceptual components of body image and its link with body ma... more We investigated the attitudinal and perceptual components of body image and its link with body mass index (BMI) in a sample of urban Gambians. We also looked at cross-cultural differences in body image and views on attractiveness between Gambians and Americans. Four groups of 50 subjects were assessed: men 14- 25y (YM); women 14-25y (YW); men 35-50y (OM); women 35-50y (OW). Socio-economic status, education, healthy lifestyle and western influences were investigated. Height and weight were measured. Body dissatisfaction was assessed with the body dissatisfaction scale of the Eating Disorder Inventory. Perceptions of body image and attractiveness were assessed using the Body Image Assessment for Obesity (BIA-O) and Figure Rating Scale (FRS). Different generations of Gambians had very different perceptions and attitudes towards obesity. Current body size was realistically perceived and largely well tolerated. Older women had a higher body discrepancy (current minus ideal body size) than other groups (p&lt;0.001). Regression analysis showed they were not worried about their body size until they were overweight (BMI=27.8 kg/m2), whilst OM, YM and YW started to be concerned at a BMI respectively of 22.9, 19.8 and 21.5 kg/m2. A cross-cultural comparison using published data on FRS showed that Gambians were more obesity tolerant than black and white Americans. The Gambia is a country in the early stage of demographic transitions but in urban areas there is an increase in obesity prevalence. Inherent tensions between the preservation of cultural values and traditional habits, and raising awareness of the risks of obesity, may limit health interventions to prevent weight gain.
Eating and Weight Disorders - Studies on Anorexia, Bulimia and Obesity, 2002
To compare the efficacy of diet alone vs interdisciplinary therapy. 256 women were divided into a... more To compare the efficacy of diet alone vs interdisciplinary therapy. 256 women were divided into an interdisciplinary therapy group composed of 102 subjects and a control group composed of 154 subjects treated by means of diet alone. 21.56% of the interdisciplinary group did not come for the 2 check-ups compared with 49.35% of the diet group (p &lt; 0.001). A weight loss of 5.88 kg and 4.18 kg for the interdisciplinary and the diet group was recorded 8 weeks after the start of the programme (second check-up). Interdisciplinary therapy is necessary to personalize treatment and satisfy the patient&#39;s desire and need for appropriate and effective management.
To investigate changes in body composition and the validity of the leg-to-leg bioimpedance (LTL) ... more To investigate changes in body composition and the validity of the leg-to-leg bioimpedance (LTL) method to measure body fat during active weight loss (WL) and weight regain (WR). Longitudinal, 12-week weight loss intervention (3.3-3.8 MJ/day) and subsequent follow-up at 1 year. Fifty-eight adult women aged between 24 and 65 years (mean age: 46.8+/-8.9 years) and with a body mass index (BMI) > or =25 kg/m(2) (mean BMI: 31.6+/-2.5 kg/m(2), range=26.0-48.2 kg/m(2)) participated in the study. Fat mass (FM) was measured at baseline, 12 weeks, 24 weeks and 52 weeks using three- and four-compartment (4-C) models, air displacement plethysmography (ADP), deuterium dilution - total body water (TBW), dual-energy X-ray absorptiometry (DXA), skinfold thickness (SFT), tetrapolar bioelectrical impedance analysis (T-BIA) and LTL. At the end of the weight loss programme, subjects lost 9.9+/-3.5 kg weight (P<0.001) and 7.6+/-0.5 kg fat (P<0.001) but after 1 year they had regained 4.9+/-3.7 k...
Although inorganic nitrate and beetroot juice supplementation are associated with decreased systo... more Although inorganic nitrate and beetroot juice supplementation are associated with decreased systolic blood pressure (BP), these results have primarily been obtained from short-term trials that focused on healthy young adults. Therefore, we hypothesized that oral supplementation of beetroot juice concentrate would decrease systolic BP in overweight older participants but that the decline in BP would not be sustained after a 1-week interruption of the beetroot juice supplementation. For 3 weeks, 24 participants were randomized to either the beetroot juice concentrate or blackcurrant juice group, with a 1-week postsupplementation phase (week 4). Changes in systolic and diastolic BP were assessed during the supplementation and postsupplementation phases. Blood pressure was measured using 3 different methods: (1) resting clinic BP, (2) 24-hour ambulatory BP monitoring, and (3) home monitoring of daily resting BP. The first 2 methods were applied at baseline and after weeks 3 and 4. Daily...
Nutrition, Metabolism and Cardiovascular Diseases, 2014
Whereas adult weight or body mass index (BMI) are directly associated with blood pressure (BP), b... more Whereas adult weight or body mass index (BMI) are directly associated with blood pressure (BP), birth weight is inversely associated with BP. The scenario for height is more complex, as both tall and short stature have been associated with higher BP. We used a theoretical model treating sitting height (SH) and tissue masses (fat mass, lean mass) as components of metabolic load, and leg length (LL) as a marker of homeostatic metabolic capacity. We predicted that decreased capacity and increased load would be independently associated with increased BP.. Anthropometry, body composition (bio-electrical impedance analysis) and BP were measured in 601 adults (228 male) aged 20-91 years from three hill villages in southern Italy. Multiple regression analysis was used to investigate associations of body composition and anthropometry with BP. Adjusting for age, systolic BP (SBP) was associated with lean mass in males, and with adiposity in females, whereas diastolic BP (DBP) was associated with fat mass in both sexes. Associations of LL and SH with BP were in opposite directions. LL was inversely associated with SBP and DBP in males, with a similar trend evident in females. SH was directly associated with SBP and DBP in females, and with DBP in males. Consistent with our theoretical model, metabolic load is associated with increased BP, though differently between the sexes, whereas metabolic capacity is independently associated with lower BP. Our findings suggest that early growth improves hemodynamic tolerance of high metabolic load in adulthood..
Abnormal body compositions such as high adiposity (HA), low muscle mass (LM), or a combination of... more Abnormal body compositions such as high adiposity (HA), low muscle mass (LM), or a combination of the 2 [high adiposity with low muscle mass (HA-LM)] are relevant phenotypes, but data on their prevalence and impact on health are still limited. This is largely because of a lack of a consensus definition for these conditions. Of particular interest is the HA-LM phenotype, also termed &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;sarcopenic obesity,&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; which may confer greater health risk. We propose a new approach for operationalizing abnormal body-composition phenotypes in a representative adult population. Whole-body dual-energy X-ray absorptiometry data obtained from the 1999-2004 NHANES were analyzed for 13,236 subjects aged ≥18 y (maximum weight and height of 136 kg and 1.96 m, respectively). Sex- and body mass index (BMI)-specific decile groups of appendicular skeletal muscle index (ASMI; kg/m(2)) and fat mass index (FMI; kg/m(2)) were developed. Cutoffs for HA and LM were incorporated into a diagnostic framework to characterize 4 specific body-composition phenotypes-low adiposity with high muscle mass, high adiposity with high muscle mass, low adiposity with low muscle mass, and HA-LM-and a subclassification of the phenotypes into classes I, II, and III. Abnormal phenotypes were prevalent across the age spectrum and BMI categories. The association between ASMI or FMI and age was modified by sex and BMI. The prevalence of HA-LM in the whole sample was 10.3% in women and 15.2% in men. The prevalence of all subclasses of HA-LM in obese women and men was 14.7% and 22.9%, respectively. HA-LM class III was more prevalent in obese men (2.3%) than in obese women (0.3%). We developed sex- and BMI-specific reference curves to harmonize the classification of body-composition phenotypes. The application of this classification will be particularly useful in the identification of cases of sarcopenic obesity. The association of these phenotypes with metabolic deregulation and increased disease risk awaits verification.
High adiposity in middle age is associated with higher dementia risk. The association between wei... more High adiposity in middle age is associated with higher dementia risk. The association between weight loss and cognitive function in older adults is still controversial. A meta-analysis was undertaken to estimate the effectiveness of intentional weight loss on cognitive function in overweight and obese adults. A structured strategy was used to search randomized and non-randomized studies reporting the effect of intentional and significant weight loss on cognitive function in overweight and obese subjects. Information on study design, age, nutritional status, weight-loss strategy, weight lost and cognitive testing was extracted. A random-effect meta-analysis was conducted to obtain summary effect estimates for memory and attention-executive domains. Twelve studies met inclusion criteria. Seven were randomized trials and the remaining five included a control group. A low-order significant effect was found for an improvement in cognitive performance with weight loss in memory (effect size 0.13, 95% CI 0.00-0.26, P=0.04) and attention/executive functioning (effect size 0.14, 95% CI 0.01-0.27, P&lt;0.001). Studies were heterogeneous in study design, sample selection, weight-loss intervention and assessment of cognitive function. Weight loss appears to be associated with low-order improvements in executive/attention functioning and memory in obese but not in overweight individuals.
The Thrifty Gene hypothesis theorizes that during evolution a set of genes has been selected to e... more The Thrifty Gene hypothesis theorizes that during evolution a set of genes has been selected to ensure survival in environments with limited food supply and marked seasonality. Contemporary environments have predictable and unlimited food availability, an attenuated seasonality due to artificial lighting, indoor heating during the winter and air conditioning during the summer, and promote sedentariness and overeating. In this setting the thrifty genes are constantly activated to enhance energy storage. Psychosocial stress and sleep deprivation are other features of modern societies. Stress-induced hypercortisolemia in the setting of unlimited food supply promotes adiposity. Modern man is becoming obese because these ancient mechanisms are efficiently promoting a positive energy balance. We propose that in today&#39;s plentifully provisioned societies, where sedentariness and mental stress have become typical traits, chronic activation of the neuroendocrine systems may contribute to the increased prevalence of obesity. We suggest that some of the yet unidentified thrifty genes may be linked to highly conserved energy sensing mechanisms (AMP kinase, mTOR kinase). These hypotheses are testable. Rural societies that are becoming rapidly industrialized and are witnessing a dramatic increase in obesity may provide a historical opportunity to conduct epidemiological studies of the thrifty genotype. In experimental settings, the effects of various forms of psychosocial stress in increasing metabolic efficiency and gene expression can be further tested.
Stable isotopic methods are considered the &quot;gold standard&quot; for the measurement ... more Stable isotopic methods are considered the &quot;gold standard&quot; for the measurement of rates of in vivo NO production. However, values reported for healthy human individuals differ by more than 1 order of magnitude. The reason for the apparent variability in NO production is unclear. The primary aim of this review was to evaluate and compare the rates of in vivo NO production in health and disease using stable isotope methods. Articles were retrieved using the PubMed electronic database. Information on concentrations, isotopic enrichments of fluxes, and conversion rates of molecules involved in the NO metabolic pathway was extracted from selected articles; 35 articles were included in the final analysis. Three protocols were identified, including the arginine-citrulline, the arginine-nitrate, and the oxygen-nitrate protocols. The arginine-citrulline protocol showed a wider variability compared to the arginine-nitrate and oxygen-nitrate protocols. The direction of the association between disease state and rate of NO production was essentially determined by the etiopathogenesis of the disorder (inflammatory, metabolic, vascular). Considerable variation in methodologies used to assess whole-body NO synthesis in humans exists. The precision of several aspects of the techniques and the validity of some assumptions made remain unknown, and there is a paucity of information about physiological rates of NO production from childhood over adolescence to old age.
Ethnic differences in the association between body mass index (BMI) and body fat suggest that bod... more Ethnic differences in the association between body mass index (BMI) and body fat suggest that body composition varies across ethnic groups. To investigate the association between impedance index - a measure of tissue resistivity - and BMI in adults of different ethnic groups (Asian Indians, West Africans and White Caucasians) living in their native countries. Male (n=329) and female (n=277) adult subjects (18-50 years) living in urban areas in the UK, The Gambia and Pakistan were studied. Body weight and height were measured and BMI calculated. The same leg-to-leg bioimpedance instrument was used in each study and impedance index (height(2) (cm)/impedance (Omega)) used as measure of tissue resistivity. In women, Asian Indians and West Africans had a significantly greater increase in impedance index per unit increase in BMI compared with white Caucasians (P&amp;amp;lt;0.001). In men, Asian Indians had a significantly lower impedance index compared with West Africans and white Caucasians (P&amp;amp;lt;0.001). Different ethnic groups may have different tissue resistivity for the same BMI indicative of systematic differences in body composition.
Eating and Weight Disorders - Studies on Anorexia, Bulimia and Obesity, 2006
We investigated the attitudinal and perceptual components of body image and its link with body ma... more We investigated the attitudinal and perceptual components of body image and its link with body mass index (BMI) in a sample of urban Gambians. We also looked at cross-cultural differences in body image and views on attractiveness between Gambians and Americans. Four groups of 50 subjects were assessed: men 14- 25y (YM); women 14-25y (YW); men 35-50y (OM); women 35-50y (OW). Socio-economic status, education, healthy lifestyle and western influences were investigated. Height and weight were measured. Body dissatisfaction was assessed with the body dissatisfaction scale of the Eating Disorder Inventory. Perceptions of body image and attractiveness were assessed using the Body Image Assessment for Obesity (BIA-O) and Figure Rating Scale (FRS). Different generations of Gambians had very different perceptions and attitudes towards obesity. Current body size was realistically perceived and largely well tolerated. Older women had a higher body discrepancy (current minus ideal body size) than other groups (p&lt;0.001). Regression analysis showed they were not worried about their body size until they were overweight (BMI=27.8 kg/m2), whilst OM, YM and YW started to be concerned at a BMI respectively of 22.9, 19.8 and 21.5 kg/m2. A cross-cultural comparison using published data on FRS showed that Gambians were more obesity tolerant than black and white Americans. The Gambia is a country in the early stage of demographic transitions but in urban areas there is an increase in obesity prevalence. Inherent tensions between the preservation of cultural values and traditional habits, and raising awareness of the risks of obesity, may limit health interventions to prevent weight gain.
Eating and Weight Disorders - Studies on Anorexia, Bulimia and Obesity, 2002
To compare the efficacy of diet alone vs interdisciplinary therapy. 256 women were divided into a... more To compare the efficacy of diet alone vs interdisciplinary therapy. 256 women were divided into an interdisciplinary therapy group composed of 102 subjects and a control group composed of 154 subjects treated by means of diet alone. 21.56% of the interdisciplinary group did not come for the 2 check-ups compared with 49.35% of the diet group (p &lt; 0.001). A weight loss of 5.88 kg and 4.18 kg for the interdisciplinary and the diet group was recorded 8 weeks after the start of the programme (second check-up). Interdisciplinary therapy is necessary to personalize treatment and satisfy the patient&#39;s desire and need for appropriate and effective management.
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Papers by M. Siervo