The role of dietary protein in weight loss and weight maintenance encompasses influences on crucial targets for body weight regulation, namely satiety, thermogenesis, energy efficiency, and body ...composition. Protein-induced satiety may be mainly due to oxidation of amino acids fed in excess, especially in diets with "incomplete" proteins. Protein-induced energy expenditure may be due to protein and urea synthesis and to gluconeogenesis; "complete" proteins having all essential amino acids show larger increases in energy expenditure than do lower-quality proteins. With respect to adverse effects, no protein-induced effects are observed on net bone balance or on calcium balance in young adults and elderly persons. Dietary protein even increases bone mineral mass and reduces incidence of osteoporotic fracture. During weight loss, nitrogen intake positively affects calcium balance and consequent preservation of bone mineral content. Sulphur-containing amino acids cause a blood pressure-raising effect by loss of nephron mass. Subjects with obesity, metabolic syndrome, and type 2 diabetes are particularly susceptible groups. This review provides an overview of how sustaining absolute protein intake affects metabolic targets for weight loss and weight maintenance during negative energy balance, i.e., sustaining satiety and energy expenditure and sparing fat-free mass, resulting in energy inefficiency. However, the long-term relationship between net protein synthesis and sparing fat-free mass remains to be elucidated.
Energy expenditure is determined by body size and body composition and by food intake and physical activity. Body size and body composition are the determinants of resting energy expenditure. Higher ...weight results in higher energy requirement through a higher resting requirement because of a higher maintenance cost of a larger body. Activity-induced energy expenditure is the most variable component of total energy expenditure. Smaller and leaner subjects generally move more as activity energy expenditure in larger subjects is not higher in proportion to the cost of moving with a higher body weight. Food intake induces changes in energy expenditure as a function of changes in body size and body composition. In addition, energy restriction induces an adaptive reduction of energy expenditure through a lowering of tissue metabolism and a reduction of body movement. An exercise-induced increase in activity expenditure is a function of the training status. In untrained subjects, exercise induces a larger increase in total energy expenditure than can be attributed to the energy cost of a training program. Trained subjects have a higher performance at the same expenditure through a higher exercise economy.
Summary
Physical activity and body composition show a typical pattern over the lifecycle. Fat‐free mass and physical performance generally peak in early adulthood. Here, evidence for a relation ...between physical activity changes over the life span and the development of sarcopenic obesity is presented. Activity‐induced energy expenditure increases with body size and physical activity during growth. The physical activity level, calculated by expressing total energy expenditure as a multiple of resting energy expenditure, gradually increases from early age to adulthood to decrease again in old age. Habitual physical activity has a significant effect on growth of fat‐free mass during adolescence and thus on peak fat‐free mass and physical performance in early adulthood. Older subjects have a lower fat‐free mass and lower physical activity levels but there is no association, suggesting physical activity does not protect against loss of lean body mass at higher age. Prevention of sarcopenic obesity starts with a physically active lifestyle to develop a healthy peak fat‐free mass and subsequent prevention of excess fat gain. The change from a physically active to a more sedentary routine in later life requires restriction of energy intake to maintain energy balance.
Abstract It is estimated that Asia will be the home of more than 100 million people with type 2 diabetes by the year of 2025. This region combines a high proportion of the world's population with ...rapidly rising diabetes prevalence rates. The increase in diabetes in Asia differs from that reported in other parts of the world: it has developed in a shorter time, in a younger age group, and in people with lower body-mass index (BMI). Studies reported that for the same BMI, Asians have a higher body fat percentage, a prominent abdominal obesity, a higher intramyocellular lipid and/or a higher liver fat content compared to Caucasians. These characteristics may contribute to a higher predisposition to insulin resistance at a lesser degree of obesity than Caucasians. The differences in body composition are more pronounced depending on the region. For the same BMI, among three major ethnic groups in Asia, Asian Indians have the highest body fat, followed by Malay and Chinese. Lower insulin sensitivity is already observed in Asian Indian adolescents with a higher body fat and abdominal obesity compared to Caucasian adolescents. In general, Asian adolescents share the same feature of body composition such as higher body subcutaneous fat, lower appendicular skeletal muscle and lower gynoid fat compared to Caucasian adolescents. This unfavourable body composition may predispose to the development of insulin resistance at later age. Genetics may play a role and the interaction with environmental factors (changes in lifestyle) could increase the risk of developing the metabolic syndrome.
Underreporting of food intake is common in obese subjects.
One aim of this study was to assess to what extent underreporting by obese men is explained by underrecording (failure to record in a food ...diary everything that is consumed) or undereating. Another aim of the study was to find out whether there was an indication for selective underreporting.
Subjects were 30 obese men with a mean (+/-SD) body mass index (in kg/m(2)) of 34 +/- 4. Total food intake was measured over 1 wk. Energy expenditure (EE) was measured with the doubly labeled water method, and water loss was estimated with deuterium-labeled water. Energy balance was checked for by measuring body weight at the start and end of the food-recording week and 1 wk after the recording week.
Mean energy intake and EE were 10.4 +/- 2.5 and 16.7 +/- 2. 4 MJ/d, respectively; underreporting was 37 +/- 16%. The mean body mass loss of 1.0 +/- 1.3 kg over the recording week was significantly different (P < 0.05) from the change in body mass over the nonrecording week, and indicated 26% undereating. Water intake (reported + metabolic water) and water loss were significantly different from each other and indicated 12% underrecording. The reported percentage of energy from fat was a function of the level of underreporting: percentage of energy from fat = 46 - 0.2 x percentage of underreporting (r(2) = 0.28, P = 0.003).
Total underreporting by the obese men was explained by underrecording and undereating. The obese men selectively underreported fat intake.
Obesity represents a strong risk factor for developing chronic diseases. Strategies for disease prevention often promote lifestyle changes encouraging participation in physical activity. However, ...determining what amount of physical activity is necessary for achieving specific health benefits has been hampered by the lack of accurate instruments for monitoring physical activity and the related physiological outcomes. This review aims at presenting recent advances in activity-monitoring technology and their application to support interventions for health promotion. Activity monitors have evolved from step counters and measuring devices of physical activity duration and intensity to more advanced systems providing quantitative and qualitative information on the individuals' activity behavior. Correspondingly, methods to predict activity-related energy expenditure using bodily acceleration and subjects characteristics have advanced from linear regression to innovative algorithms capable of determining physical activity types and the related metabolic costs. These novel techniques can monitor modes of sedentary behavior as well as the engagement in specific activity types that helps to evaluate the effectiveness of lifestyle interventions. In conclusion, advances in activity monitoring have the potential to support the design of response-dependent physical activity recommendations that are needed to generate effective and personalized lifestyle interventions for health promotion.
Objective: Assessment of a possible relationship between perception of satiety and diet-induced thermogenesis, with different macronutrient compositions, in a controlled situation over 24 h. Design: ...Two diets with different macronutrient compositions were offered to all subjects in randomized order. Setting: The study was executed in the respiration chambers at the department of Human Biology, Maastricht University. Subjects: Subjects were eight females, ages 23-33 y, BMI 23 +/- 3 kg/m(2), recruited from University staff and students. Interventions: Subjects were fed in energy balance, with protein/carbohydrate/fat: 29/61/10 and 9/30/61 percentage of energy, with fixed meal sizes and meal intervals, and a fixed activity protocol, during 36 h experiments in a respiration chamber. The appetite profile was assessed by questionnaires during the day and during meals. Diet induced thermogenesis was determined as part of the energy expenditure. Results: Energy balance was almost complete, with non-significant deviations. Diet-Induced-Thermogenesis (DIT) was 14.6 +/- 2.9%, on the high protein/carbohydrate diet, and 10.5 +/- 3.8% on the high fat diet (P < 0.01). With the high protein/high carbohydrate diet, satiety was higher during meals (P < 0.001; P < 0.05), as well as over 24 h (P < 0.001), than with the high fat diet. Within one diet, 24 h DIT and satiety were correlated (r = 0.6; P < 0.05). The difference in DIT between the diets correlated with the differences in satiety (r = 0.8; P < 0.01). Conclusion: In lean women, satiety and DIT were synchronously higher with a high protein/high carbohydrate diet than with a high fat diet. Differences (due to the different macronutrient compositions) in DIT correlated with differences in satiety over 24 h.
Obesity results from protracted energy imbalance. Whether this comprises excessive energy intake, lowered physical activity or both, remains disputed.
Physical activity energy expenditure, evaluated ...in three different ways from daily energy expenditure (DEE) measured using doubly labelled water, was examined for trends over time. Data included subjects in Europe (Maastricht, the Netherlands) and North America extending back to the 1980s. These data were compared with measures from the third world, and measures made on wild terrestrial mammals.
Physical activity expenditure in Europe (residual of the regression of DEE on basal energy expenditure (BEE)) has slightly but significantly increased since the 1980s. There was no trend over time in physical activity level (PAL=DEE/BEE), or in the residual variance in DEE once mass, sex and age were accounted for. This latter index of physical activity expenditure also significantly increased over time in North America. DEE of individuals in Europe and North America was not significantly different from individuals measured in the third world. In wild terrestrial mammals, DEE mostly depended on body mass and ambient temperature. Predicted DEE for a 78 kg mammal living at 20 degrees C was 9.2 MJ per day (95% CI: 7.9-12.9 MJ per day), not significantly different from the measured DEE of modern humans (around 10.2-12.6 MJ per day).
As physical activity expenditure has not declined over the same period that obesity rates have increased dramatically, and daily energy expenditure of modern man is in line with energy expenditure in wild mammals, it is unlikely that decreased expenditure has fuelled the obesity epidemic.
Summary
The field of application of accelerometry is diverse and ever expanding. Because by definition all physical activities lead to energy expenditure, the doubly labelled water (DLW) method as ...gold standard to assess total energy expenditure over longer periods of time is the method of choice to validate accelerometers in their ability to assess daily physical activities. The aim of this paper was to provide a systematic overview of all recent (2007–2011) accelerometer validation studies using DLW as the reference. The PubMed Central database was searched using the following keywords: doubly or double labelled or labeled water in combination with accelerometer, accelerometry, motion sensor, or activity monitor. Limits were set to include articles from 2007 to 2011, as earlier publications were covered in a previous review. In total, 38 articles were identified, of which 25 were selected to contain sufficient new data. Eighteen different accelerometers were validated. There was a large variability in accelerometer output and their validity to assess daily physical activity. Activity type recognition has great potential to improve the assessment of physical activity‐related health outcomes. So far, there is little evidence that adding other physiological measures such as heart rate significantly improves the estimation of energy expenditure.
The 9th Stock Conference acknowledged the complex background of genetic, cultural, environmental and evolutionary factors of obesity. Gene–environment interactions underlie the flexibility in ...body‐weight and body‐fat regulation, illustrated by the hunter‐gatherers' feast and famine lifestyle, the variation in physical activity over the lifespan being highest at reproductive age, the variation in energy intake through ‘eating in the absence of hunger’, while running the risk of exceeding the capacity of triacylglyceride storage, leading to lipotoxicity and metabolic problems. Perinatal metabolic programming for obesity via epigenetic changes in response to a ‘Western diet’ results in production of lipid‐poor milk and metabolically efficient pups, contributing to the perpetuation of obesity throughout generations. Evolutionary insight from comparative physiology and ecology indicates that over generations activity‐induced energy expenditure has remained the same compared to wild mammals, that energy balance might be dependant on protein balance, while the function of taste changed from detection of poison or energy to social drinking and social behaviour. At present, the impact of assortative mating on obesity prevalence is unambiguously positive. The complexity that appeared can only be fully appreciated by setting the data into the context of our evolutionary history.
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