Abstract
Reduction in energy intake below the acceptable level of requirement for an individual results in a series of physiological and behavioural responses, which are considered as an adaptation to the low energy intake. This ability of the human body to adapt to a lowering of the energy intake is without doubt beneficial to the survival of the individual. However, what is more controversial is the view held by some that the body can metabolically adapt in a beneficial manner to a lowered intake and consequently that the requirements for energy are variable given the same body size and composition and physical activity levels. Much of this confusion is the result of considerable evidence from studies conducted in well-nourished adults who, for experimental or other reasons, have lowered their intakes and consequently demonstrated an apparently enhanced metabolic efficiency resulting from changes in metabolic rates which are disproportionate to the changes in body weight. Similar increases in metabolic efficiency are not readily seen in individuals who on long-term marginal intakes, probably from childhood, have developed into short-statured, low-body-weight adults with a different body composition. It would thus appear that the generally used indicator of metabolic efficiency in humans, that is a reduced oxygen consumption per unit fat free mass, is fraught with problems since it does not account for variations in contributions from sub-compartments of the fat free mass which include those with high metabolism at rest such as brain and viscera and those with low metabolism at rest such as muscle mass. Metabolic rate per unit fat free mass thus, does not reflect true variations in metabolic efficiency and is due largely to variations in body composition. This finding combined with the evidence that behavioural adaptation in habitual physical activity patterns which occurs on energy restriction is not necessarily beneficial to the individual raises doubts about the role of adaptation to low intakes in determining one’s requirement for energy. The evidence is overwhelming that both in children and adults, changes in body size and composition as well as in levels of habitual physical activity may be the most important consequences of a lowered energy intake and cannot be assumed to be a part of a beneficial adaptation that influences energy requirements.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Shetty, P. Adaptation to low energy intakes: the responses and limits to low intakes in infants, children and adults. Eur J Clin Nutr 53 (Suppl 1), s14–s33 (1999). https://doi.org/10.1038/sj.ejcn.1600741
Published:
Issue Date:
DOI: https://doi.org/10.1038/sj.ejcn.1600741
This article is cited by
-
Issues related to the assessment of energy balance during short-term over-, under- and refeeding in normal weight men
European Journal of Clinical Nutrition (2023)
-
Muskuloskeletale Merkmale bei unter- und normalgewichtigen Auszubildenden im klassischen Bühnentanz
Zentralblatt für Arbeitsmedizin, Arbeitsschutz und Ergonomie (2023)
-
Stunting in infancy, pubertal trajectories and adult body composition: the Birth to Twenty Plus cohort, South Africa
European Journal of Clinical Nutrition (2021)
-
Reasons for and Consequences of Low Energy Availability in Female and Male Athletes: Social Environment, Adaptations, and Prevention
Sports Medicine - Open (2020)
-
Remembering Prakash Sarvotham Shetty MD, PhD, FRCP [1943–2018]
European Journal of Clinical Nutrition (2018)