Body composition at high altitude: a randomized placebo-controlled trial of dietary carbohydrate supplementation

Macdonald, Jamie; Oliver, Samuel J.; Hillyer, Kelly; Sanders, Stephan; Smith, Zoë; Williams, Catherine J.; Yates, Danny; Ginnever, Hazel; Scanlon, Edward F.; Roberts, Edward; Murphy, David; Lawley, Justin S.; Chichester, Eleanor

doi:10.3945/ajcn.2009.28075

Cited by 37 publications

(32 citation statements)

References 39 publications

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“…The reduced energy intake at 4559 m confirms previous findings at similar altitudes 388 where both males and females were shown to reduce their energy intake by more 389 than 30% after ascent to 4300 -5100 m [15,21,33,40]. The present study extends 390 these findings by providing a systematic analysis of certain factors that may 391 contribute to the energy intake reducing effect of hypoxia following rapid ascent to 392 16 high altitude.…”

Section: Energy Intake 387supporting

confidence: 78%

Disturbed eating at high altitude: influence of food preferences, acute mountain sickness and satiation hormones

et al. 2012

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PURPOSE: Hypoxia has been shown to reduce energy intake and lead to weight loss, but the underlying mechanisms are unclear. The aim was therefore to assess changes in eating after rapid ascent to 4,559 m and to investigate to what extent hypoxia, acute mountain sickness (AMS), food preferences and satiation hormones influence eating behavior. METHODS: Participants (n = 23) were studied at near sea level (Zurich (ZH), 446 m) and on two days after rapid ascent to Capanna Margherita (MG) at 4,559 m (MG2 and MG4). Changes in appetite, food preferences and energy intake in an ad libitum meal were assessed. Plasma concentrations of cholecystokinin, peptide tyrosine-tyrosine, gastrin, glucagon and amylin were measured. Peripheral oxygen saturation (SpO(2)) was monitored, and AMS assessed using the Lake Louis score. RESULTS: Energy intake from the ad libitum meal was reduced on MG2 compared to ZH (643 ± 308 vs. 952 ± 458 kcal, p = 0.001), but was similar to ZH on MG4 (890 ± 298 kcal). Energy intake on all test days was correlated with hunger/satiety scores prior to the meal and AMS scores on MG2 but not with SpO(2) on any of the 3 days. Liking for high-fat foods before a meal predicted subsequent energy intake on all days. None of the satiation hormones showed significant differences between the 3 days. CONCLUSION: Reduced energy intake after rapid ascent to high altitude is associated with AMS severity. This effect was not directly associated with hypoxia or changes in gastrointestinal hormones. Other peripheral and central factors appear to reduce food intake at high altitude. DOI: https://doi.org/10.1007/s00394-012-0366-9Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-62402 Accepted Version Originally published at: Aeberli, Isabelle; Erb, Annina; Spliethoff, Kerstin; Meier, Daniela; Götze, Oliver; Frühauf, Heiko; Fox, Mark; Finlayson, Graham S; Gassmann, Max; Berneis, Kaspar; Maggiorini, Marco; Langhans, Wolfgang; Lutz, Thomas A (2013). Disturbed eating at high altitude: influence of food preferences, acute mountain sickness and satiation hormones. European Journal of Nutrition, 52 (2) Purpose Hypoxia has been shown to reduce energy intake and lead to weight loss, 36 but the underlying mechanisms are unclear. The aim was therefore, to assess 37 changes in eating after rapid ascent to 4559 m and to investigate to what extent 38 hypoxia, acute mountain sickness (AMS), food preferences, and satiation hormones 39 influence eating behavior. 40Methods Participants (n=23) were studied at near sea level (Zurich (ZH), 446 m) and 41 on two days after rapid ascent to Capanna Margherita (MG) at 4559 m (MG2 and 42 MG4). Changes in appetite, food preferences and energy intake in an ad libitum meal 43were assessed. Plasma concentrations of cholecystokinin, peptide tyrosine-tyrosine, 44 gastrin, glucagon and amylin were measured. Peripheral oxygen saturation (SpO2) 45 was monitored and AMS assessed using the Lake Louis score. 46Results Energy intake from the ad...

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Section: Energy Intake 387supporting

confidence: 78%

Disturbed eating at high altitude: influence of food preferences, acute mountain sickness and satiation hormones

et al. 2012

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“…However, some evidence suggests that body mass and body composition can be maintained at HA in both active and sedentary populations if they are highly motivated, educated, strongly encouraged and empowered to meet their energy needs [8,23]. In contrast to this, more recent work has shown weight loss can occur despite adequate carbohydrate supplementation [43]. There is no convincing evidence that intestinal malabsorption plays a role in negative energy balance observed at HA [44].…”

Section: Mission Reality: Acute Metabolic Demands and Responses In Thmentioning

confidence: 99%

Energy at High Altitude

2011

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For the military doctor, an understanding of the metabolic effects of high altitude (HA) exposure is highly relevant. This review examines the acute metabolic challenge and subsequent changes in nutritional homeostasis that occur when troops deploy rapidly to HA. Key factors that impact on metabolism include the hypoxic-hypobaric environment, physical exercise and diet. Expected metabolic changes include augmentation of basal metabolic rate (BMR), decreased availability of oxygen in peripheral metabolic tissues, reduction in VO2 max, increased glucose dependency and lactate accumulation during exercise. The metabolic demands of exercise at HA are crucial. Equivalent activity requires greater effort and more energy than it does at sea level. Soldiers working at HA show high energy expenditure and this may exceed energy intake significantly. Energy intake at HA is affected adversely by reduced availability, reduced appetite and changes in endocrine parameters. Energy imbalance and loss of body water result in weight loss, which is extremely common at HA. Loss of fat predominates over loss of fat-free mass. This state resembles starvation and the preferential primary fuel source shifts from carbohydrate towards fat, reducing performance efficiency. However, these adverse effects can be mitigated by increasing energy intake in association with a high carbohydrate ration. Commanders must ensure that individuals are motivated, educated, strongly encouraged and empowered to meet their energy needs in order to maximise mission-effectiveness.

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“…The contribution of lowered energy intake to hypoxia-induced muscle atrophy has been investigated at high altitude (34), but the effects of normobaric hypoxia on energy intake and signaling pathways regulating protein turnover in skeletal muscle have not been studied earlier to our knowledge. Protein turnover is the balance between protein synthesis and protein degradation.…”

mentioning

confidence: 99%

Distinct responses of protein turnover regulatory pathways in hypoxia- and semistarvation-induced muscle atrophy

Theije¹,

Langen

Lamers³

et al. 2013

American Journal of Physiology-Lung Cellular and Molecular Phys

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de Theije CC, Langen RC, Lamers WH, Schols AM, Köhler SE. Distinct responses of protein turnover regulatory pathways in hypoxia-and semistarvation-induced muscle atrophy. Am J Physiol Lung Cell Mol Physiol 305: L82-L91, 2013. First published April 26, 2013 doi:10.1152/ajplung.00354.2012.-The balance of muscle protein synthesis and degradation determines skeletal muscle mass. We hypothesized that hypoxia-induced muscle atrophy and alterations in the regulation of muscle protein turnover include a hypoxia-specific component, in addition to the observed effects of reduction in food intake in response to hypoxia. Mice were subjected to normoxic, hypoxic (8% oxygen), or pair-fed conditions for 2, 4, and 21 days. Cell-autonomous effects of hypoxia on skeletal muscle were also assessed in differentiated C2C12 myotubes. Hypoxia induced an initial rapid loss of body and muscle weight, which remained decreased during chronic hypoxia and could only in part be explained by the hypoxia-induced reduction of food intake (semistarvation). Regulatory steps of protein synthesis (unfolded protein response and mammal target of rapamycin signaling) remained active in response to acute and sustained hypoxia but not to semistarvation. Activation of regulatory signals for protein degradation, including increased expression of Murf1, Atrogin-1, Bnip3, and Map1lc3b mRNAs, was observed in response to acute hypoxia and to a lesser extent following semistarvation. Conversely, the sustained elevation of Atrogin-1, Bnip3, and Map1lc3b mRNAs and the increased activity of their upstream transcriptional regulator Forkhead box O1 were specific to chronic hypoxia because they were not observed in response to reduced food intake. In conclusion, altered regulation of protein turnover during hypoxia-induced muscle atrophy resulted from an interaction of semistarvation and a hypoxia-specific component. The finding that food restriction but not hypoxia-induced semistarvation inhibited regulatory steps in protein synthesis suggests a hypoxiaspecific impairment of the coordination between protein-synthesis signaling and protein-degradation signaling in skeletal muscle. hypoxia; mouse model; protein turnover; regulation; skeletal muscle WEIGHT LOSS AND MUSCLE ATROPHY are common features in advanced chronic obstructive pulmonary disease (COPD). In addition to nutritional imbalance, systemic inflammation, and progressive inactivity, hypoxemia has been implicated as a trigger for muscle atrophy in patients with COPD. Hypoxemia is a symptom during the whole course of the disease with chronic hypoxemia in end-stage COPD and acute hypoxemic episodes during exacerbations (50). Understanding the mechanisms by which hypoxia induces muscle atrophy will benefit the treatment of this disease because loss of muscle mass is a strong predictor of mortality and significantly increases disease burden (8,17,25,35,57). Although exposure to hypobaric hypoxia at high-altitudes results in muscle atrophy in men and animals (5,11,21,23), it is still under debate whether hypoba...

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Body composition at high altitude: a randomized placebo-controlled trial of dietary carbohydrate supplementation

Cited by 37 publications

References 39 publications

Disturbed eating at high altitude: influence of food preferences, acute mountain sickness and satiation hormones

Disturbed eating at high altitude: influence of food preferences, acute mountain sickness and satiation hormones

Energy at High Altitude

Distinct responses of protein turnover regulatory pathways in hypoxia- and semistarvation-induced muscle atrophy

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