METABOLIC STUDIES IN STARVATION
Authors: ASHLEY B. C. E. , WHYTE H. M. 
Published: August 2017

Three obese females were studied during starvation (0 to 500 Calories per day) and light activity for 18, 28 and 34 days, during which they were given vitamins and liberal amounts of water, and two of them were given electrolytes. Studies were then continued on two subjects given 500 Calorie diets with contained protein.

They experienced little or no hunger, and no untoward effects except halitosis, slight ketonuria and sensitivity to cold. Weight loss amounted to 9.3, 14.1 and 9.5 kg., averaging 810, 330, 250 and 250 grammes per day in successive weeks. This was analysed in terms of its components by the methods usually used in metabolic studies and indirect calorimetry.

Protein catabolism declined as starvation proceeded to a minimum level of 12 to 25 grammes per day. It was decreased by norethandrolone and by carbohydrate feeding. The average daily losses of protein during succeeding weeks were 55, 36, 28 and 18 grammes. Overall, protein accounted for 7.6% to 9.1% of the weight loss and provided 5.0% to 6.9% of the caloric expenditure. Protein lost during starvation ranged from 704 to 1156 grammes, which represent 2.8 to 4.6 kg. of muscle and other cellular tissues. Creatinine excretion gradually fell; it accounted for about 5% of the nitrogen loss initially and 15% in the later stages.

Carbohydrate losses were estimated at 495 to 1050 grammes, accounting for 3.5% to 11.0% of the weight loss and for 3.0% to 6.4% of the Calories. Fat losses amounted to 4.1 to 6.5 kg., being 44% to 68% of the weight loss and providing 87% to 90% of Calories. The average daily loss of fat was 215 grammes. The gaseous exchanges and respiratory quotient fell, and the basal metabolic rate fell more steeply than the body weight or surface area.

Water balance was estimated from measurements and calculations made in two slightly different ways, and the total body water was measured in one subject. All items of losses and gains were determined daily, including metabolic water and evaporation. The cumulative net losses of water reached a peak of 6.2 litres in one subject and were 3.8, 6.0 and 1.2 litres at the end of starvation in the three subjects. The final “corrected” water balances, when allowance was made for the discharge of cell water associated with protein catabolism and for possible initial imbalances, were —1.6, —1.1 and +0.5 litres.

Serum electrolyte levels showed only minor changes. Potassium, sodium and chloride were apparently retained in store in the two subjects who were given these electrolytes. There was a net loss of potassium in all subjects, but in two the potassium balance was normal when account was taken of electrolytes released from cellular breakdown.

Observations from this study and from the literature have been interpreted as emphasizing the idea that (a) negative nitrogen balance means the amputation of cells so that cellular water and electrolytes are released in proportion to the protein catabolized, and (b) the “desirable” or normal water balance recognizes a constant volume of extracellular fluid plus an intracellular volume which is proportionate to the cellular protein mass. This concept, the nature of obesity tissue, nitrogen metabolism and the possible importance of essential amino acids and of creatinine metabolism are discussed.