Minnesota starvation experiment.

Keys' 1945 Minnesota Starvation Experiment. One of the semi-starvation study participants is being examined.

This post is a work in progress.

Last update and review: October 27, 2019.


The changes that Keys and colleagues observed and described in their study of prolonged semi-starvation(1) are similar to what is observed today in many people who went on the currently popular restrictive diets and entered a state of prolonged caloric restriction.

The Minnesota starvation experiment of 1945.

Under the direction of Dr. Ancel Keys at the University of Minnesota a group of 34 young men, previously normal and well-nourished, have completed six months of partial starvation under rigidly controlled conditions. During 6 months, the diet of the participants contained about 1600 calories. During the starvation period, the energy expenditures of the subjects were kept at the 3300 calorie level.

"Relaxation". Pronounced emaciation  is visible in the study subjects by the 4-th months of semi-starvation experiment. From Keys, 1945.
“Relaxation”. Pronounced emaciation is visible in the study subjects by the 4-th months of semi-starvation experiment. From Keys, 1945.

Skin.

More than half of the men exhibited a patchy brownish pigmentation most frequently distributed around the mouth and around
the eyes in a “spectacle effect, but occasionally such pigmented patches were seen elsewhere on the body. Almost all of the men exhibited a slight or moderate degree of cyanosis, most conspicuous in the nail beds but frequently seen in the lips as well.

Definition of spectacle from Meriam-Webster dictionary:
something (such as natural markings on an animal) suggesting a pair of glasses.

The description of changes in skin during the Minnesota starvation experiment is interesting. Many of the changes described below can also be observed in individuals on low carb diets who excessively restricted their caloric intake.

The skin was dry, cold and thin to the touch and, in many cases, was roughened in one or more large areas. Follicular pouting and hyperkeratosis, mostly of slight degree, was suggested in 25 of the men. In a few cases there was plugging and pigmentation of follicles but generally the condition waw represented only by a “permanent gooseflesh” appearance. Skin biopsies taken from 6 of the men showing more pronounced changes disclosed only relatively slight histological abnormality.

Here is a comment by other observers who visited Keys’ laboratory and found that the changes in the semi-starved subjects of the experiment were similar to what they saw in liberated Europe in 1944 and 1945.

At least 65% of the subjects had demonstrable dependent edema and many had brownish pigmentation of their skin. Practically all exhibited a pronounced sinus bradycardia with resting pulse rates in the low thirties.

Loss of fat, tissues and an increase in body fluids.

The graph and the description that follows are extremely interesting. They notably describe how human organs shrink in individuals who undergo prolonged starvation or caloric restriction.

We have been researching this topic, focusing in particular on the potential of the “shrank” by starvation human organs to regenerate. In mice, it was established that organs reduced in size by fasting can regenerate upon refeeding. It is a lot less clear what happens with human organs in the same situation.

Fig. 12. WEIGHT COMPARTMENTS OF THE BODY. Total weight and weights of od~y compartments. Flasma estimated by the dye method; blood cells from plasma volume and hem2atroorit; extra-.cellular fluid from the thiocyanate method; fat from the specific gravity; bones estimated from Mitchell, H. H., T. S. Hamilton, F. R. Stegyerda and H. W. Bean (J.B.C., vol. 158, p. 625, 194f5) The fluid volume is the extra-cellular'volume minus the blood volume. Average values for 7 man. From Keys et al., 1945. The changes in the major compartments in the body are portrayed in Figure 12. Assuming the skeleton to be substantially constant, we find the body "tissue" apparently decreased to 18.0 kg., from an itial average of 30.5 kg., a loss of 41%. In this "tissue" represents everything except fat, bone, blood and interstitial fluid.
Fig. 12. WEIGHT COMPARTMENTS OF THE BODY. Total weight and weights of od~y compartments. Plasma estimated by the dye method; blood cells from plasma volume and hem2atroorit; extra-.cellular fluid from the thiocyanate method; fat from the specific gravity; bones estimated from Mitchell, H. H., T. S. Hamilton, F. R. Stegyerda and H. W. Bean (J.B.C., vol. 158, p. 625, 194f5) The fluid volume is the extra-cellular volume minus the blood volume. Average values for 7 men. (From Keys et al., 1945.)
The changes in the major compartments in the body are portrayed in Figure 12. Assuming the skeleton to be substantially constant, we find the body “tissue” apparently decreased to 18.0 kg., from an initial average of 30.5 kg., a loss of 41%. In this “tissue” represents everything except fat, bone, blood and interstitial fluid.

The changes in the major compartments in the body are portrayed in Figure 12. Assuming the skeleton to be substantially constant, we find the body “tissue” apparently decreased to 18.0 kg., from an initial average of 30.5 kg., a loss of 41%. In this “tissue” represents everything except fat, bone, blood and interstitial fluid.

Shrinking organs.

The heart shrinks a lot semi-starving humans. This is confirmed by other observations.

The heart was consistently and markedly reduced in size by the starvation. This change was clearly evident by the middle of the starvation period and became progressively more pronounced. Two typical cases are shown in Figures 19 and 20. While the measurements are not completed it appears that the total heart size shrank more than in proportion to the body weight, perhaps as much as the calculated “tissue” change mentioned above (41%). The uncertain element of the residual blodd volume in the heart must be recognized but in any case a substantial and probably very large loss of actual cardiac tissue was sustained.

The decrease in heart size after 6 months of semi-starvation. From Keys, 1945.
The decrease in heart size after 6 months of semi-starvation. From Keys, 1945.

Waist circumference.

The waist circumference did not decrease. This is also something that is observed in inadvertently calorically restricted health enthusiasts. Increased body fluids partially explain this observation. Constipation and gastro-intestinal issues were not of considerable significance.

The abdominal girth (circumference) did not decrease on the average and, in some individuals, was actually larger at the end of starvation than at the start. It must be presumed that this points strongly toward ascites or edema of the abdominal viscera or both. Numerous examinations failed to disclose free fluid in the abdomen or chest in any subject but the methods are anything but sensitive.

Intellectual function.

The intellectual function remained intact in the participants after 6 months of semi-starvation and loss of lean mass.

By and large, however, none of the intellective tests showed
any appreciable response to semi-starvation. This result might seem at variance with the subjective statements of the men that in general they felt a decline in intellectual power. On closer examination, however, it appeared that the subjective belief reflected primarily mental lethargy, lack of ambition and general depression. Apparently the mental ability remained untouched but the will to
use it declined except under the special stimulus of test situations.

Personality changes.

The changes that Keys and colleagues describe are similar to what is observed in many people who went on the currently popular diets and entered a state of prolonged caloric restriction.

Simple observation, showed that semi-starvation works profound changes on personality, attitude, social behavior and all those relatively intangible items that go to make up what is popularly referred to as “personal psychology”.

An important development was an increasing tendency to introversion.
Social contacts became “too much trouble,” “too tiring,” and just plain “dull”.
Sex interest evaporated rather early and physical lethargy ruled out many forms of extraverted behavior. Ordinary conversation and discussion were limited by the strong tendency of each men to talk chiefly about his personal symptoms, weight and functional peculiarities.

The depression, hypochondriasis and hysteria scores increased
significantly and, in many cases, to extents as marked as are encountered in psychoneurotic patients. Much less prominent changes were observed on the psychopathic scales such as the schizophrenia or paranoia scores.

Sleep.

The description of sleep is similar to what is experienced today by many people on low carb diets.

Sleep was highly variable but the average result seemed to be a need for more than the previous amount, though this was often broken up in several portions.

The diet.

The study details of the Minnesota Starvation Experiment by Keys and colleagues, 1945.
The study details of the Minnesota Starvation Experiment by Keys and colleagues, 1945.

Additional details on different study parameters can be found in the screenshots below.

Keys' 1945 Minnesota Starvation Experiment. One of the semi-starvation study participants is being examined.
Keys’ 1945 Minnesota Starvation Experiment. One of the semi-starvation study participants is being examined.

References:

1. Keys, A., Brozek, J., Henschel, A., Mickelsen, O. & Taylor, H. L. (1945) Experimental Starvation in Man. A Report from the Laboratory of Physiological Hygiene, University of the Minnesota  University of Minnesota, Minneapolis, MN.

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