1570 cal. a day with meals carbohydrate rich and protein poor with an emphasis on potatoes, cabbage, macaroni, and whole wheat bread while maintaining an active lifestyle, including the 22-miles of walking each week sounds like a very possible long term SHTF situation.The Great Starvation Experiment, 1944-1945One of the greatest killers of World War II wasn't bombs or bullets, but hunger. As the conflict raged on, destroying crops and disrupting supply lines, millions starved. During the Siege of Leningrad alone, over a thousand people a day died from lack of food. But starvation also occurred in a more unlikely place: Minneapolis, Minnesota. It was here that, in 1945, thirty-six men participated in a starvation experiment conducted by Dr. Ancel Keys.
Keys standardized their diet, allowing them 3200 calories a day, while simultaneously putting them through a battery of tests to gather data on variables such as their heart size, blood volume, hearing, vision, fitness, body fat, and even sperm count. He also ordered the men to maintain an active lifestyle, working jobs in the lab and walking a minimum of 22 miles a week.
Keys abruptly cut the food intake of the men from 3200 calories a day down to 1570. The starvation phase of the experiment had begun. He carefully controlled the amount they ate by serving them two meals a day prepared and weighed by the cook he had on staff. He designed the meals to be carbohydrate rich and protein poor, simulating what people in Europe might be eating, with an emphasis on potatoes, cabbage, macaroni, and whole wheat bread (all in meager amounts). Despite the reduction in food, Keys insisted the men maintain their active lifestyle, including the 22-miles of walking each week.
Effects of the reduced food intake quickly became apparent. The men very soon showed a remarkable decline in strength and energy. Keys charted a 21-percent reduction in their strength, as measured by their performance on a back lift dynamometer. The men complained that they felt old and constantly tired.
http://www.madsciencemuseum.com/msm/pl/great_starvation_experiment