General Starvation

Starvation, a condition in which the body draws on its own internal reserves for energy, arises from normal processes essential to survival. These processes lead to the disease of general starvation, or undernutrition, only after progressing beyond a threshold where damage resulting in functional incompetencies is done to active tissue. If starvation is not acute, that is, not rapidly induced, dysfunctions incompatible with heavy work are not apparent in nonobese people before the loss of 10 percent of prestarvation weight.

Ordinary starvation may be said to begin some 4 or 5 hours after a meal. It is then that the liver begins to release as glucose its store of glycogen. As this process continues, muscle and adipose (fatty) tissue, which otherwise rely on free glucose for fuel, gradually revert to the oxidation of fatty acids. This allows circulating glucose to be consumed primarily by the brain.

Liver glycogen alone in the absence of any food intake supplies glucose to the blood for roughly 12 to 16 hours before a number of metabolic changes begin shifting liver activity to gluconeogenesis, the conversion of muscle protein into glucose. Within 24 hours or longer, depending on the level of food intake, liver glucose output is fully dependent on imported protein. With the onset of gluconeogenesis, the liver itself burns fatty acids delivered from adipose tissue. As these arrive in increasing amounts, only partial oxidation occurs. This results in the liver sending ketones (incompletely burned fatty acids) into circulation. These become fuel for both muscle and brain as their level in the blood increases. In the case of rapidly induced starvation, keto acid concentrations can reach dangerous levels, resulting in dehydration and, eventually, in coma. This, however, can be avoided by the intake of small amounts of carbohydrate.

Gluconeogenesis continues for about a week before ketone production levels off. Muscle gradually ceases to be reliant on keto acids, making ever greater use of free fatty acids liberated from adipose tissue. The brain now takes ketone bodies over glucose for nourishment. This allows gluconeogenesis to shut down, eliminating the demands of this process on muscle protein. At this point, the body's metabolism is fully adjusted to draw on fat for almost all of its energy needs.

Protein catabolism and the destruction of active tissue is never totally eliminated, however. Wasting, loss of weight or body mass, the most obvious external manifestation of general starvation, is most precipitous during the first few days. It becomes less so over a longer period. If semistarvation extends over weeks or months, the rate of wasting will continue to decline. Fat accounts for the greatest portion of wastage after the first several days, but to the end there is a relatively slight but slowly increasing usage of protein.

This continuing attrition of protein, even as fat remains available, is not borne equally by all organs of the body. Heart and kidney tissue sustain slightly less loss than would be expected given their proportion of total body mass. The liver, intestines, and skin incur more than their share of the loss. Postmortem examinations of starvation victims reveal no part of the body immune to atrophy except the brain.

During famine, starvation initially affects those who are physiologically the most vulnerable. Different forms of protein-energy malnutrition, kwashiorkor and marasmus, show up early in young children. Before gross weight loss is seen in older children and adults, there is a loss of endurance. Those who are afflicted require frequent rests from work. As general starvation becomes more advanced, there are complaints of weakness and muscle pains. Movement becomes sluggish. Individuals sit or lie down whenever possible. A slow, shuffling gait develops. Nocturnal sleep is interrupted, but total sleep progressively increases. An acute sensitivity to noise develops; the skin becomes extremely sensitive and bruises easily. There are complaints about feeling cold. Blood pressure and heart rate decline. A diarrhea attributed to visceral atrophy and malfunction occurs in individuals who are free of intestinal infection. Edema often appears, first in the face, then in the extremities, later in the abdominal and thoracic cavities.

Whereas the intellect remains largely unimpaired, the emotions are greatly affected. Victims' moods alternate between apathy and extreme irritability. The starving become discouraged and depressed but also display an exaggerated ill temper. Critical ability seems to fail. There is lack of concentration and lapse of memory. Speech becomes slow. Appearance and manners become matters of indifference. Interest in sex disappears. Women experience amenor-reah; spermatogenesis declines in men. An inversion takes place: Light hair appears on women's faces, whereas men's beards stop growing. Both sexes lose hair from the top of the head and around the genitals. Victims think only of their diseased condition and food. But when starvation becomes acute, even appetite disappears.

The length of time a starving individual can survive on endogenous sources of energy varies, depending on fat reserves, the magnitude of caloric deficit (determined by energy intake and level of physical activity), and ambient temperature. Inactive individuals with normal weight for height can endure nearly total starvation for about 2 months. Semistar-vation in active subjects consuming between 1,300 and 1,600 kilocalories per day has been studied under controlled conditions for up to six months. During a famine food intake may fall below this level but often for only brief periods of time at first. Hence, victims can endure for months. Once a 30

percent weight loss is incurred, however, the chances of survival are virtually nil without medical intervention. A 40 percent wastage during famine is almost certainly fatal.

Individuals suffering from advanced undernutrition can survive for prolonged periods owing to two remarkable means of accommodation that allow the energy budget to reach near equilibrium and permit weight loss to slow dramatically despite a very low level of caloric intake. The first is a decline in basal metabolism, which occurs because wasting reduces the number of metabolically active cells, accompanied by a decrease in the metabolic rate of the surviving biomass. The second is a decline in spontaneous movements and a decreased cost of movement. In other words, starving people reduce their actions to a minimum. Moreover, any activity that cannot be avoided becomes less expensive energywise because of reduced weight. Of these two factors, curtailed activity accounts for the greatest savings. In experiments conducted during World War II, volunteers restricted to a semistarvation diet for 6 months were observed to reduce movement-related energy expenditures by 71 percent. Approximately 60 percent of this was achieved by elective curtailment of activity. A reduction of anywhere near this magnitude during a famine is bound to have profound social implications.

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