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Information about Dynamic Energy Budget

Dynamic Energy Budget (DEB) theory aims to identify simple quantitative rules for the organization of metabolism of individual organisms that can be understood from basic first principles, The word "Dynamic" refers to the life cycle perspective of the theory, where the budget changes dynamically over time.

Cornerstones of the theory are:
  • conservation of mass, energy and time,
  • relationships between surface area and volume
  • stoichiometric constraints on production
  • organisational uncoupling of metabolic modules
  • strong and weak homeostasis
  • partionability of reserve kinetics
They are essential to understand evolution of metabolic organisation since the origin of life.

DEB theory delineates reserves, as separate from structure. Reserves are synthesised from environmental substrates (food) for use by the metabolism for the purpose of somatic maintenance (including protein turnover, maintenance of concentration gradients across membranes, activity and other types of work), growth (increase of structural mass), maturity maintenance (installation of regulation systems, preparation for reproduction, maintenance of defence systems, such as the immune system), maturation (increase of the state of maturity) and reproduction. This organisational position of reserve creates a rather constant internal chemical environment, with only an indirect coupling with the extra-organismal environment. Reserves as well as structure are taken to be generalised compounds, i.e. mixtures of a large number of compounds, which do not change in composition. The latter requirement is called the strong homeostasis assumption. Polymers (carbohydrates, proteins, ribosomal RNA) and lipids form the main bulk of reserves and of structure.

Some reasons for including reserve are to give an explanation for:
  1. the metabolic memory; changes in food (substrate) availability affect production (growth or reproduction) with some delay. Growth continues for some time during starvation; embryo development is fuelled by reserves
  2. the composition of biomass depends on growth rate. With two components (reserves and structure) particular changes in composition can be captured. More complex changes require several reserves, as is required for autotrophs.
  3. the body size scaling of life history parameters. The specific respiration rate decreases with (maximum) body size between species because large bodied species have relatively more reserve. Many other life history parameters directly or indirectly relate to respiration.
  4. the observed respiration patterns, which reflect the use of energy. Freshly laid eggs hardly respire, but their respiratory rates increase during development while egg weight decreases. After hatching, however, the respiration rate further increases, while the weight now also increases
  5. all mass fluxes are linear combinations of assimilation, dissipation and growth. If reserves are omitted, there is not enough flexibility to capture product formation and explain indirect calorimetry.


The standard model quantifies the metabolism of isomorphs with 1 reserve and 1 structure that feeds on one type of food with a constant composition. The rules for the standard model for reproducing multicellulars, and modified for dividing unicellulars, are:

Assumptions of the standard model

  • The state variables of the individual are structural mass and reserve; they have a constant composition (strong homeostasis).
  • Food is transformed into reserve, which fuels all other metabolic processes
  • The reserve density at birth equals that of the mother at egg formation. Foetuses develop similarly, but receive unrestriced amount of reserve from the mother during development.
  • Stage transitions occur if the cumulated investment into maturation exceeds threshold values. These stages typically are: embryo, juvenile and adult.
  • Somatic maintenance is proportional to structural body volume, and maturity maintenance to maturity but maturity does not increase in the adult stage. Heating costs for endotherms and osmostic work (for fresh water organsism) are proportional to surface area.
  • The feeding rate is proportional to the surface area; food handling time and the transformation efficiency from food to reserve are independent of food density.
  • The reserves must be partitionable (i.e. mergable), such that the dynamics is not affected and weak homeostasis applies.
  • A fixed fraction (called kappa) of mobilized reserve is allocated to somatic maintenance plus growth, the rest on maturity maintenance plus maturation or reproduction.
  • During starvation, individuals always give priority to somatic maintenance and follow one of two possible strategies:
    • they do not change the mobilization of reserve (so continue to invest in maturation or reproduction)
    • cease energy investment in maturation and reproduction (thus changing mobilization of reserve).


    • These assumptions quantify all energy and mass fluxes in an organism (including heat, dioxygen, carbon dioxide, ammonia) and imply rules for the covariation of parameter values across species (body size scaling relationships).

    Extensions of the standard model

    DEB theory has been extended into many directions, such as
    • effects of changes is shape during growth (e.g. V1-morphs and V0-morphs)
    • inclusion of more types of food (substrate), which requires Synthesizing Units to model
    • inclusion of more reserves (which is necessary for organisms that do not feed on other organisms) and more structures (which is necessary to deal with plants)
    • the formation and excretion of metabolic products (which is a basis for syntrophic relationships, and useful in biotechnology)
    • the production of free radicals (linked to size and nutritional status) and their effect on survival (aging)
    • the growth of body parts (including tumours)
    • effects of chemical compounds (toxicants) on parameter values and the hazard rate (which is useful to establish no effect concentrations for environmental risk assessment): the DEBtox method
    • processes of adaptation (gene expression) to the availability of substrates (important in biodegradation)
    DEB theory provides constraints on the metabolic organisation of sub-cellular processes. Together with rules for interaction between individuals (competition, syntrophy, prey-predator relationships), it also provides a basis to understand population and ecosystem dynamics. The theory, therefore, links various levels of biological organisation (cells, organisms and populations). A considerable number of popular empirical models turn out to be special cases of the DEB model, or very close numerical approximations.

    External links

    Metabolism is the complete set of chemical reactions that occur in living cells. These processes are the basis of life, allowing cells to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories.
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    A mass balance (also called a material balance) is an application of conservation of mass to the analysis of physical systems. By accounting for material entering and leaving a system, mass flows can be identified which might have been unknown, or difficult to measure without this
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    Energy balance has the following meanings in several fields:
    • In physics, energy balance is a systematic presentation of energy flows and transformations in a system.

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    The time balance for an individual organism refers to the fact that components of the behaviour have to compete for time if they exclude each other.The Dynamic Energy Budget theory for metabolic organisation makes explicit use of time, energy and mass balances..
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    Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry) is the calculation of quantitative (measurable) relationships of the reactants and products in chemical reactions (chemical equations).
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    modules, both anatomically and in their metabolism. Anatomical modules are usually segments or organs. When we look at illustrations of metabolic reactions, we find that they, too, are modular: we can clearly identify, for instance, the citric acid cycle as a complex network that
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    Homeostasis is the property of either an open system or a closed system, especially a living organism, to regulate the state of its internal environment so as to maintain a stable, constant condition.
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    Reserve in the context of the Dynamic Energy Budget theory means the set of metabolites (mostly polymers and lipids) that the organism can use for metabolic purposes. These compounds can have active metabolic functions, however. They are not just "set apart for later use".
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    Maintenance of an organism is the collection of processes to stay alive, excluding prodiction processes. The Dynamic Energy Budget theory delineates two classes
    • Somatic maintenance.

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    Individual growth is the increase in structural mass of an individual organism, in the context of the Dynamic Energy Budget theory. This frequently (but not always) goes with an increase in weight.
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    Maintenance of an organism is the collection of processes to stay alive, excluding prodiction processes. The Dynamic Energy Budget theory delineates two classes
    • Somatic maintenance.

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    immune system is a collection of mechanisms within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own healthy
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    Maturation could refer to any of the following:
    • Fetal development
    • Developmental biology
    • Emotional development
    • Or physical maturation of any biological life form - see individual articles for maturation of different life forms.

    See Also

    • Mature

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    Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
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    A generalized compound is a mixture of chemical compounds of constant composition, despite possible changes in the total amount. The concept is used in the Dynamic Energy Budget theory, where biomass is partitioned into a limited set of generalised compounds, which contain a high
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    Homeostasis is the property of either an open system or a closed system, especially a living organism, to regulate the state of its internal environment so as to maintain a stable, constant condition.
    ..... Click the link for more information.
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    Proteins are large organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues.
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    Ribosomal RNA (rRNA), a type of RNA synthesized in the nucleolus by RNA Pol I, is the central component of the ribosome, the protein manufacturing machinery of all living cells.
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    Lipids can be broadly defined as any fat-soluble (hydrophobic), naturally-occurring molecules. The term is more-specifically used to refer to fatty-acids and their derivatives (including tri-, di-, and monoglycerides and phospholipids) as well as other fat-soluble sterol-containing
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    Reserve in the context of the Dynamic Energy Budget theory means the set of metabolites (mostly polymers and lipids) that the organism can use for metabolic purposes. These compounds can have active metabolic functions, however. They are not just "set apart for later use".
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    MeSH D013217 Starvation is a severe reduction in vitamin, nutrient, and energy intake, and is the most extreme form of malnutrition. In humans, prolonged starvation (in excess of 1-2 months) causes permanent organ damage and, eventually, death.
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    For the use of the term in ecology, see .
    Biomass refers to living and recently dead biological material which can be used as fuel or for industrial production.
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    autotroph (from the Greek autos = self and trophe = nutrition) is an organism that produces complex organic compounds from simple inorganic molecules and an external source of energy, such as light or chemical reactions of inorganic compounds.
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    Body size scaling relationships are relationships between a physiological quantity (such as the respiration rate, or the maximum reproduction rate) of organisms and their body size (frequently taken to be body weight).
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    In animal physiology, respiration is the transport of oxygen from the ambient air to the tissue cells and the transport of carbon dioxide in the opposite direction. This is in contrast to the biochemical definition of respiration, which refers to cellular respiration
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    In most birds and reptiles, an egg (Latin ovum) is the zygote, resulting from fertilization of the ovum. To enable incubation the egg is usually kept within a favourable temperature range as it nourishes and protects the growing embryo.
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    respiratory rate (or respiration rate) is the number of breaths a living being, such as a human, takes per minute.

    There is only limited research on monitoring alien respiratory rate, and these studies have focused on such issues as the inaccuracy of respiratory rate
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    Calorimetry is the science of measuring the heat of chemical reactions or physical changes. Calorimetry involves the use of a calorimeter. The word calorimetry is derived from the Latin word calor, meaning heat.
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    An isomorph is an organism that does not change in shape during growth. The implication is that its volume is proportional to its cubed length, and its surface area to its squared length.
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