Spontaneous fast is a major characteristic of the annual cycle of sea birds when breeding or moulting on land, whereas they feed exclusively at sea. In situations where food is lacking or not used, the allocation of limited endogenous resources causes trade-offs between competing traits, such as reproduction, somatic growth and maintenance. During food deprivation, animals cannot maximize all of their life-history traits and must exhibit adaptive behavioural, physiological and biochemical responses to reduce metabolism and/or the cost of current activities in order to maintain biological value (Wang et al., 2006). Among sea birds, penguins, especially the Aptenodytes genus, which inhabits cold environments, have evolved to tolerate some of the greatest relative body mass losses and to survive several months of starvation, which can be up to 5 months in winter-acclimatized king penguin chicks (Cherel and Le Maho, 1985; Groscolas, 1990; McCue, 2010).