This article originally appeared in Issue 4 of our magazine.

Here’s a cold hard fact: Overwhelmingly, urban dwellers are unprepared to face crises, their hope placed on FEMA or other disaster relief agencies to meet their post-crisis needs. Not having groceries is just one of those concerns.

Few would contest the notion that a well-nourished individual would thrive better than one merely trying to survive in the aftermath of a catastrophe. But, do you always need a sandwich to survive?

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You may have incurred injuries. In addition to all your other gear, can you carry a 10-day supply of calories for yourself or your family? If not, who’s going to carry the 10-day water supply for each of them? Plus, you all may be on foot … and you may have to carry a child as well.

This intentionally provocative article examines the extreme situation of involuntary, near-total starvation, post-crisis in urban North America. Humans are actually more adaptable to starvation than generally appreciated. Healthy adults can benefit from an alternative strategy by understanding the adaptation process and how it might be optimized by simple oral supplements — versus having to carry a conventional calorie sub-load in your kit.

Are there precedents for urban starvation that we can study to develop a crisis calorie management plan? The truth is that there haven’t been any modern U.S. urban disasters where starvation-related mortality was a major concern, mostly because otherwise healthy adults can easily withstand fasting for three to five days, by which time disaster relief resources have usually managed to provide food and supplies to those directly affected by the crisis.

So for our purposes in this article, we’re looking beyond simply being hungry for three to five days, instead focusing on two distinct conditions of involuntary starvation beyond five days.
Individuals may be subjected to total or near-total starvation. With the former, no hydration and no caloric intake occurs — in this case, you will perish due to dehydration stress alone, generally surviving several days to a week or two depending on the individual. In the latter case of near-total starvation, you’re presumed to have access to at least nominal hydration levels, but otherwise no other essential micro-nutrients (vitamins) and caloric intake.

Get Informed

We can actually find relevant information on near-total starvation, both voluntary and involuntary. There are many examples that we can examine: professional entertainers in the late 1800s, who deliberately starved themselves in public at great length for fame and notoriety; starvation during polar desert expeditions; emaciated POWs in concentration camps; severe mental health disorders such as anorexia; prisoner hunger strikes; and even some specific medical studies, including the Minnesota Starvation Experiment (1944-’45) and the Iowa prison studies (1969).

The determinants of how long you can endure starvation include:

• Availability of hydration
• Initial body fat and protein stores
• Calorie demand based on environment (e.g. cold, strenuous, etc.)
• Initial health status (e.g. significant trauma accelerates the pace of starvation demise)
• Gender (women have a slight survival advantage)
• Age extremes (very young and old have limited fat and protein reserves)

In the past 50 years, the only well-documented involuntary near-total starvation in a North American survival situation is the story of Carla Corbus and her mother. After a small plane crash in California’s Trinity Mountain range during the winter of 1967, they survived starvation for at least 54 days before dying. Carla’s daily diary entries were published in the Saturday Evening Post in 1968. Incidentally, their tragic story was the impetus for legislation mandating transponder beacons for aircraft.

A normally proportioned 160-pound person requires approximately 1,200 calories per day to avoid adapting to fasting and starvation metabolism. Our metabolic sensors monitor our bodies and ensure that our brain tissues continuously receive a steady supply of their preferred energy source, glucose (carbohydrates). Upon sensing a caloric restriction, body stores of glucose, particularly muscle and liver glycogen, are consumed within 72 hours to nourish the brain and other critical tissues. And after only 12 hours of fasting, the next day’s carbohydrate calorie needs are already being sourced by metabolically cannibalizing body stores of fat and protein.

In fact, practically all of your body fat is expendable without serious adverse effects. The human body has a mechanism for us to sustain long periods of starvation — by allowing brain tissue to readily utilize the byproducts of fat and protein metabolism, transformed into glucose and ketones. The brain can derive two-thirds of its energy from ketones, synthesized mostly from fat, allowing humans to survive near-total starvation for 60 to 90 days.

Proteins, however, play a more critical role in maintaining normal body function. Their uncontrolled depletion during starvation results in loss of tissue architecture, blood elements, enzymes, and muscle mass, as well as impairment of our immune system. Unlike fat, precious body water is required to eliminate toxic byproducts of protein metabolism. So, if our bodies were only able to utilize our protein stores to maintain brain tissue, we would only survive for 20 to 30 days. In short, if you lose more than one-third to half of your total body protein, that’s all she wrote.

Starvation also depletes non-calorie essential micro-nutrients, particularly vitamin C (ascorbic acid) and vitamin B-1 (thiamine). Unlike most other animals, humans cannot synthesize vitamin C, nor store thiamine in large quantities. Vitamin C deficiency causes scurvy; thiamine deficiency causes beriberi. Without these vitamins, calorie energy utilization and critical tissue repair mechanisms fail within weeks. Despite having non-citrus food and water, more than 2 million sailors died of scurvy from the years 1500 to 1800, more than were ever claimed by naval warfare itself.

Above: If there’s an emergency evacuation and you have to flee the city on foot, at least be sure to grab a 10- to 21-day supply of glucose and multi-vitamin tablets. That’s a lot easier than toting three week’s worth of groceries.

Have a Plan

Providing even nominal amounts of glucose calories favors the metabolizing of body fat stores, rather than precious protein. As little as ¼ ounce of carbohydrates during starvation reduces protein waste by about 50 percent. This tiny bit of intervention generates roughly 8.5 ounces of metabolic water, sufficient to sustain daily requirements under limited conditions. It also conserves body water otherwise required to excrete protein waste products. In great part, this is how black bears survive their months of winter hibernation — humans just cannot do it to the same extent as bears.

What does this mean practically? Simply take two 4-gram glucose tablets per day, and you will conserve precious protein calories and body water. Take a daily multi-vitamin containing C and thiamine, and you will support your critical metabolism mechanisms.

So realistically, the prospect of long-term near-total starvation in North America is a most unlikely scenario.

And by understanding human adaptation to starvation, we can devise unconventional strategies to limit wasted protein and sustain micro-nutrients when faced with limited access to nourishment.

While attempting to escape the city on foot, a 10- to 21-day supply of glucose and multi-vitamin tablets is a lot easier to tote and maintain than the same amount of groceries. Plan on hearing your stomach complain, but answer it with the higher priority of hydration, and take your pills. Relying on stockpiled food is obviously ideal, but it's not the only way to make it through a short-term crisis without starving.

So there’s your food for thought — you don’t always need a sandwich to survive.

Tip: Storing Vitamins and Supplements

To keep vitamins and other dietary supplements at their peak potency for longer, it’s best to store them in a cool, dry place. Avoid places like the refrigerator and bathroom medicine cabinet where humidity and temperature differences can reduce their effective shelf life. Certain vitamins and supplements could require specific storage methods such as being kept out of light, so do keep them in their original packaging. Vitamins lose their strength with time, so be mindful of their expiration dates and swap them out when needed.

Written by M. Duffy, MD