Some authors reported that the SDA of foods may serve a useful physiological purpose to the maintenance of thermal balance in a cold environment. But how and how much effect has SDA upon the extra heat produced dy cold stimulus is out of sight yet.
Our present experiments were carried out in Autumn 1954, to examine how much extra calories above basal metabolism produced by cold stimulus in the fasting men may be spared by the ingestion of different kinds of foods.
Our subjects were two healthy men of us who lied on bed with only a sheet of blanket during 5 hours after meal in the air-conditioned chamber of 0°C±2°C room temperature.
The test meals are shown in table I. These contained, in every case, about 1000 calories for the subject S. S. and about 800 calories for the subject S. N., adjusted to both body sizes.
The results obtained were as follows:
1) The extra calories above basal metabolism produced by the cold stimulus in the fasting men during 5 hours postprandium were 25.5% (subject S. S.) and 20.7% (subject S. N.) of each basal metabolism, but the extra calories produced by the cold stimulus after the ingestion of the high protein diet were 12.8% (S. S.) and I. O % (S. N.) of each basal metabolism. Therefore, 12.7% (S. S.) and 19.7% (S. N.), of the basal metabolism. or 50% (S. S.) and 95% (S. N.) of the extra heat produced by the cold stimulus in the fasting state were diminished following the ingestion of the diet. (table 4.)
2) In the high carbohydrate diet, 10.5% (S. S.) and 8.7% (S. N.) of the basal metabolism, or 41.% (S. S.) and 42% (S. N.) of the extra heat produced by the cold stimulus in the fasting state were diminished following the ingestion of the diet. (table 4.)
3) In the high fat diet, 6.1% (S. S.) and 5.9% (S. N.) of the basal metabolism, or 24% (S. S.) and 29% (S. N.) of the extra heat produced by the cold stimulus in the fasting state were diminished following the ingestion of the diet. (table 4.)
4) The high protein diet has the largest, while the high fat diet has the smallest sparing action of extra heat production by cold stimulus.
These figures all in above were estimated on the assumption that the value of SDA of food would be constant in any environmental temperature.
5) The effect of the ingestion of food on the skin temperature in cold environment was almost negligible as in figure 2 and table 6.
