Hunger kills: how does the body try to cope?

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Victims of starvation face a severe state where their body fat, muscles and tissues burn up for fuel. The body of a victim of starvation literally consumes itself by deteriorating rapidly, all in an attempt to provide fuel for survival.

In the fasted or pre-starvation state, the body’s main concern is to maintain blood glucose. This is because many tissues in the body need it as a constant supply for energy. The brain, for example, requires 120g per day, therefore, if a decrease in glucose levels is detected, the breakdown of glycogen stores (stored carbohydrates) is encouraged. This releases glucose which can be used to supply tissues and organs of the body with energy. In more severe cases where hunger extends to a longer period of time, a series of changes occur in the body.

                                                         Phases of starvation

(1) Gluconeogenesis

Gluconeogenesis is defined as the production of glucose; in starvation this is the first phase, developing on the 2nd or 3rd day without proper feeding. Gluconeogenesis occurs when glycogen stores have decreased, therefore, the only way to maintain blood glucose levels (for energy) is to produce more for the brain as well as other tissues that depend on glucose. The main signal for this phase is the drop in insulin and glucagon ratios. In this phase, amino acids alanine and glutamine are converted into glucose. However, around 1.75g of protein is required for each 1g of glucose and the brain itself uses 100-120g of glucose per day, therefore, should the body continue to use amino acids to provide glucose, a serious reduction of muscle tissue would occur as a result.

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(2) Period of adaptation

In this phase (up to 3 weeks), the body realises that it cannot continue to use important amino acids to make glucose for energy. To spare the concentrations of glucose available, the muscles attempt to spare glucose by adapting to using fatty acids as a source of energy instead. The brain (which usually uses glucose as a source energy) adapts to using ketone bodies instead (a compound usually made from fatty acids). On the other hand, ketone bodies are acidic in high concentrations and even in the state of starvation, ketone concentrations do not exceed 8mM. However, in individuals with uncontrolled diabetes, the effects of the presence of starvation are far worse. For those with uncontrollable diabetes who are in the starved state, the concentration of ketone bodies can exceed up to 25-30mM which can result in a condition known as ketoacidosis. Ketoacidosis causes extreme symptoms such as abdominal pain, confusion, extreme thirst and high blood glucose levels.

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(3) Adapted starvation

After 3 weeks of starvation, the body reaches a steady state where there is a gradual reduction of protein mass and fat stores. If re-feeding does not occur, the individual is likely to die from a number of diseases associated with starvation before actually starving to death. For example, individuals in the adapted phase of starvation will have used up the antibodies (blood proteins used in response to antigens) that would have been used to fight off invading bacteria, to provide amino acids for energy – these people will have an increased susceptibility to infections which will then result in death. In developing countries, the presence of HIV, the development of malaria or onset of diarrhoea is sufficient enough to cause death if that individual is starved because they no longer have a means of protection or defence against viruses or bacteria.

Adults often make an almost complete recovery from starvation following re-feeding, however, in children who recover, the signs of starvation will be visible in adulthood (e.g. they may be mentally stunted, physically stunted and will have an increased susceptibility to many diseases). In developing countries where there are repeated periods of famine, the ability to survive is severely compromised. This is because recovery from the previous famine would not have occurred to allow for the rebuilding of fat and glycogen stores. These people are the most vulnerable to the inevitable state of hunger and its deadly consequences.

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