PROJECT REPORT 
COMMITTEE ON FOOD RESEARCH 
QUARTERMASTER FOOD AND CONTAINER INSTITUTE 
FOR THE ARMED FORCES 
CHICAGO ILLINOIS 
RESEARCH AND DEVELOPMENT BRANCH 
MILITARY PLANNING DIVISION 
OFFICE OF THE 
QUARTERMA8TER GENERAL 
COOPERATING INSTITUTION 
Yals University 
LOCAL I TY 
vew TTpven, Conn. 
01 V! si on , , „ „ 
School of J eriicine 
OEP ART* EN^ai3ora^ory phySi0X0gy 
OFFICIAL I N VESTI GATOR 
John R. Brobeck 
COLL ABORATO RS 
REPORT NO. 
7 
C?t I-cm- 7019 5 
FOR PERIOD COVERING 
June 1 - Sent, 30, 1947 
P-1007 
INITIATION DATE , 
October 1, 1946 
TITLE: [ ] PROGRESS REPORT [ , PHASE REPORT [ ] ANNUAL REPORT [ JtERMINATION REPORT 
"Fffect of food and environment on food intake” 
SUMMARY 
In two previous reports (nos. 2 and 3), submitted to 
the Committee on Pood Research of the Cuartemaster Food 
a~d Container Institute, the reactions of rets upon exposure 
for 18 hours to temperatures ranging from 35* to 95* F. have 
bee-- described, "civ these reactions have been studied more 
precisely, and food intake, changes in body weight and body 
temperature, and water intake have all been measured over the 
temperature range of 65* to 97* F. Results have been summer! zed 
on four graphs, figs. 1-4, 
CQMO FORM 
5 Apr I I 46 
I 2“ i 2 I (Revised) 
1 ir rats 
Purpose: To investigate/the possibility that food intake is a 
mecha^ism of temperatore regulation, »j, 
Procedure: Adult nale rats o'0 the $nrpgue-Pawlev strain were 
ac’c11zed to a temperature of 82-84° F, j and then exposed for 
18 hours in groans of 8-8 to a temperature snv,e''her6 
within the range of 85° to 97® F. and water intakes were 
measured, and bodv tewne-aiure body weight were recorded at 
the beginning and end of each 18-hour experiment* 
Food and water were always given ad libitum; the food 
used both during the acclimatization and the experimental periods 
was dry calf real (0-. L* F* ) 
Results: intake slowly fell as temperature increased 
from' 65 a to 90° F., then fell more rapidly until at 97* tp„ the 
rats a~e little or not at all. There was a sharp break in the 
curve (see fig. l) bet-res’- 90° a-d 94® F. 
? ost of the rots shewed a rise in body temperai.tn’-e following 
an 18-hour exnosure to temperatures of 72* 7, or less; this rise 
seemed to be a consequence of increased motor activity. At ?6°~ 
90* , bodv temperature tell during the experiments, presumably 
because the animals were usually ouiot or sleaning when the 
final measurements ware begun. At 94° T;'», body temperature 
rcso by the sane amount as at 68”, but for a different reason, 
namolv, the rat’s inability to dissipate heat ranidly enough to 
nrovert mild fever. (It will bo recalled that at 94° F. the food 
intake fell sharply.) At 97° v.y average body temperature changes 
'were gains of from 2 to .8 degrees F. (fir. 2). 
Between temperatures of 68° and 86” F., most rats gained 
about 5 grams overnight; at ?0'J F* no gain occurred; at 
94° F. a loss of 20 gm. was woted, while at h7" F. the losses 
amounted to 30 gm. or more (fig. 8). 
"alter intake was reaaonablv constant between 68” and 90° 
F., but rose sharply in the 94° a-d 9?° experiments (fig. 4). 
Significances These data demonstrate the precision with which 
rats""Vegulrte their energy exchange, and sug est that it is 
nossible either to measure or to control most if not all of the 
variable involved in t*is exchange. 
They also sug est that bodv weight is a none important 
■‘'actor in determining the intake at certair temperatures 
than at others. Its importance seems to be greatest in the range 
tc which the animals have been acclimatized (fig. l). 
Comparison data, obtained at 68° and at 94" p# further 
suggests that food intake mav be an important mechanism of 
P-1307 #7 temperature regulation* At both of these tenreretries the rats 
exhibited nild hyperthermia a"ter 18 hours. At PF°, this hyper- 
thermia was evoked by the cold stress and was accomnanied by 
a high food intake• at 94° the fever was a token, of the animal's 
inability to lose heat easilv> and was associated with a very 
low food intake, pood intake is hot determined by the absolute 
bod"'/ temperature, the^efo'^e, but by the conditions' temnev,a tore 
regulation existing at any ;iver time, BecP’ se its heat of 
utilization (specific dvnam.ic actio’'' or •°.,T).A.), ford is in 
itself a mild heat stress, and the ability of the or nanism to 
use this extra heat seems to a certain extent to determine the 
food ".r-ake, 
publicationsr 
Probeck, John p« Food intake as a nechr.nisa of temperature 
regulation in rats, (In preparation,) 
P-1007 Figure 1. Relation between food intake and 
environmental temperature. Each point 
represents a group of 5 - 6 rats. The 
three symbols on this and the other graphs 
identify rats according to body weight, 
as follows: 
Body weight averaging 236 - 267 gm. 
Body weight averaging 284 - 307 gm. 
Body weight averaging 315 - 330 gm. 
P-1007 #7 Figure 2. Relationship between overnight 
change in body temperature and 
environmental temperature. For 
meaning of symbols, please see fig. 1. 
P-100? #7 Figure 3• Relationship, between overnight 
change in body weight and environmental 
temperature. For meaning of symbols, 
please see fig. 1. 
P-10 >7 #7 
6 Figure 4; Relationship between water intake 
and environmental temperature. For 
meaning of symbols, please see fig. 1. 
P-1007 J^7 
7