Zitat:
Zitat von Matthias75
Und was sollen wir jetzt daraus über die Ursachen von Übergewicht lernen?
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Na dann hätte ich wohl besser das Abstract der Original-Studie verlinken sollen, wenn das nicht klar wird, was die Forscher sagen wollen:
Zitat:
Pontzer H, Raichlen DA, Wood BM, Mabulla AZP, Racette SB, et al. (2012) Hunter-Gatherer Energetics and Human Obesity. PLoS ONE 7(7): e40503.
Western lifestyles differ markedly from those of our hunter-gatherer ancestors, and these differences in diet and activity level are often implicated in the global obesity pandemic. However, few physiological data for hunter-gatherer populations are available to test these models of obesity. In this study, we used the doubly-labeled water method to measure total daily energy expenditure (kCal/day) in Hadza hunter-gatherers to test whether foragers expend more energy each day than their Western counterparts. As expected, physical activity level, PAL, was greater among Hadza foragers than among Westerners. Nonetheless, average daily energy expenditure of traditional Hadza foragers was no different than that of Westerners after controlling for body size. The metabolic cost of walking (kcal kg−1 m−1) and resting (kcal kg−1 s−1) were also similar among Hadza and Western groups. The similarity in metabolic rates across a broad range of cultures challenges current models of obesity suggesting that Western lifestyles lead to decreased energy expenditure. We hypothesize that human daily energy expenditure may be an evolved physiological trait largely independent of cultural differences.
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Zitat:
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Our results indicate that active, “traditional” lifestyles may not protect against obesity if diets change to promote increased caloric consumption. Thus, efforts to supplement diets of healthy populations in developing regions must avoid inundating these individuals with highly-processed, energy-dense but nutrient-poor foods. Since energy throughput in these populations is unlikely to burn the extra calories provided, such efforts may unintentionally increase the incidence of excess adiposity and associated metabolic complications such as insulin resistance. Indeed, processed, energy-dense foods have been linked to insulin resistance and cardiovascular disease among Australian foragers transitioning to village life
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Der Standpunkt der "Conventional Wisdom" lautet: Übergewicht als epidemisches Phänomen unserer Zeit resultiert aus der unlimitierten Verfügbarkeit hochkalorischer Nahrungsmittel
und lebensstilbedingtem niedrigerem bewegungsbedingtem Energieverbrauch als das in früheren Zeiten der Fall war.
Der zweite Teil dieser Hypothese wird durch diese Studie in Frage gestellt.
Vulgo: "Iss weniger und beweg Dich mehr" als Therapie oder Präventionsvorschlag ist zumindest für den "Beweg-Dich- Mehr"-Teil in Frage zu stellen.
EDIT: Auch
diese Studie an den Pima-Indianern kommt zum Ergebnis, dass es wohl weniger die Bewegung ist, die Übergewicht bei diesem Volk erklärt, sondern Energieaufnahme und niedriger Grundumsatz - nicht aber (zu) niedriger Leistungsumsatz.
Zitat:
(...)
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.
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Auch dieser neulich erst erschienene Beitrag stellt die bislang gängige Energy-Expenditure-These in ihrer Bedeutung für das Phänomen in Frage:
Zitat:
Dis Model Mech. 2012 Sep;5(5):569-73. doi: 10.1242/dmm.010553.
Fat: an evolving issue.
Speakman JR, O'Rahilly S.
Abstract
Work on obesity is evolving, and obesity is a consequence of our evolutionary history. In the space of 50 years, we have become an obese species. The reasons why can be addressed at a number of different levels. These include separating between whether the primary cause lies on the food intake or energy expenditure side of the energy balance equation, and determining how genetic and environmental effects contribute to weight variation between individuals. Opinion on whether increased food intake or decreased energy expenditure drives the obesity epidemic is still divided, but recent evidence favours the idea that food intake, rather than altered expenditure, is most important. There is more of a consensus that genetics explains most (probably around 65%) of weight variation between individuals. Recent advances in genome-wide association studies have identified many polymorphisms that are linked to obesity, yet much of the genetic variance remains unexplained. Finding the causes of this unexplained variation will be an impetus of genetic and epigenetic research on obesity over the next decade. Many environmental factors - including gut microbiota, stress and endocrine disruptors - have been linked to the risk of developing obesity. A better understanding of gene-by-environment interactions will also be key to understanding obesity in the years to come.
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