"The history of man is in large part the chronicle of his quest for food," wrote Ancel Keys, an early researcher in obesity. Even the Bible is replete with references to fears of inadequate food supplies. Remember Pharaoh's dream of the seven fat cows and seven lean cows that Joseph interpreted to mean seven lean years and seven years of plenty? Now, if ancient humans feared not having enough food (hunger), why is it that thousands of years later in 2011, people who have access to plenty of food often don't eat enough and experience hunger? Why would people intentionally face hunger? Could it have to do with some crazy diet concept like calorie restriction? Yes. Many folks attempt to lose weight by eating less food than they need. Some even experience hunger while taking appetite suppressants. Again why do people intentionally starve? What are the physiological and psychological effects of hunger?
Ancel Keys was one of the first to conduct a long-term scientific study of hunger and semi-starvation. During World War II, while some countries like Holland were in the throes of famine, (and American parents were telling their children to eat everything on their plates because children were starving in Europe), Keys devised an experiment with more than 30 male conscientious objector volunteers. These men were willing to restrict their food intake substantially for several months for the purpose of providing detailed information on the psychological and physiological effects of caloric restriction. Called the "Minnesota semi-starvation experiment," Keys documented his results in an enormous two-volume book. Over the course of the experiment, the men were to lose about 25% of their weight by caloric restriction and exercise and then spend three months in rehabilitation.
Keys' study, though published over 60 years ago, can give us some clues to why dieting by food restriction can be so difficult for so many people. What he found was that with prolonged under-nutrition, hunger sensations become "progressively accentuated," unlike in total fasting where feelings of hunger may dissipate after a few days. Keys, incidentally, reported that Jews in the Warsaw Ghetto in 1942 were barely subsisting on 600 to 800 calories a day. People in his own experiment were given almost twice as many.
During the experiment, Keys' subjects became totally preoccupied with food. They would often dawdle for hours over their meal, and they developed "striking changes" both physically and mentally. The men became depressed, listless, unable to concentrate, socially withdrawn, and apathetic. They also began to neglect their personal appearance: they no longer brushed their teeth, combed their hair, or shaved. And they lost all interest in sex. Keys called the syndrome "semi-starvation neurosis." Incidentally, some researchers more recently believe that hunger causes cognitive changes in people such that those who go on "hunger strikes" have serious mental changes that result in impaired decision skills.
The 3-month rehabilitation period in Keys' study, was even harder for some than the period of caloric restriction. The men ate thousands of calories (some up to 10,000 calories) a day and still felt unsatisfied-what was called a "post-starvation hyperphagia." The speculation was that their bodies were attempting to recover not just the fat they had lost but the loss of their lean body tissue-often gaining more weight than their initial weight--a process called "overshooting."
