黑色字體是原文獻(xiàn)

紅色字體是機(jī)翻

藍(lán)色字體是人肉翻，校對(duì)，講解，注釋，批注，說明。。。等等?

Starvation in Man

G. F. CAHILL JR

In creatures in whom mobility plays an important role in survival, the five

to tenfold greater efficiency of storage of excess calories as fat instead of

protein or carbohydrate is crucial. This is particularly true for terrestrial and

avian species who must struggle continuously against gravity. Thus in man,

who once survived as a hunter and gatherer, and in whom mobility also

played an important role in his competition with other creatures and,

unfortunately, frequently against fellow man, storage of calories as triglyceride in adipose tissue was mandatory for survival. Thus, as discussed

elsewhere in this issue, as man eats, the first priority is to provide fuel for

immediate metabolic requirements. The second is to expand his modest

glycogen reserves in liver and muscle and also to replace the amount of

protein broken down in various tissues since the last meal, particularly in

muscle. The third priority is to convert the excess, i.e. the originally ingested

calories as carbohydrate, protein or fat, into triglyceride and to store the

calories in adipose tissue.

In fasting, the priorities are reversed. The body undergoes a series of

hormonal and metabolic changes to draw selectively on its extensive supply of

calories in adipose tissue, and to spare the breakdown of vitally needed

proteins, such as those involved in muscle contractility or in enzymes in

critical structures such as heart or liver, or, even more important, proteins

involved in nervous tissues, particularly brain, which appear not to be

mobilised at all during starvation. This chapter will discuss these various

adaptations to a deficit caloric economy, and will describe how the human

body progressively and preferentially uses fat for energy.

ENERGY STORES

First, an overall account of calories in various forms and tissues is necessary

to provide perspective to fuel economy and mobilisation in man (Table 1). A

normal adult uses 1 to 1.2 Cal/min to maintain basal energy needs, or 1500 to

1800 Cal/day. With standard physical activity or in a cold environment, this

is doubled, and with strong physical activity, daily expenditures may increase

to 5000 to 6000 Cal/day. Thus the 100000 to 150000 Calories in the 12 to 16

kg of triglyceride in fat provides one to three months of survival fuel

Clinics in Endocrinology and Metabolism -- Vol. 5, No. 2, July 1976. 397?