How Many Calories Do You Need to Survive?

All of our food preps are basically fuel preps, but instead of fuel for a generator or our vehicles, our food serves as fuel and calories for our bodies.

open beef and black beans MRE
open beef and black beans MRE

Just like all of our other devices that require a certain amount of fuel to function, it is worth considering how many calories our bodies need for optimum function and a minimum level of subsistence.

Proper rationing of food is a necessary factor when assessing any survival situation. To perform the needed calculations, we must know how many calories are needed, per day, for survival.

Anywhere from 1,800 calories to 2,400 calories a day are needed for optimum function in a survival situation.

As a general rule, men need more than women, with an adult male requiring calories on the upper end of the scale, with an adult female requiring calorie levels on the lower end.

SexAge (Years)Daily Kilocalories to Survive
Both2 – 31,000 – 1,400
Both4 – 81,400 – 1,600
Female9 – 131,600 – 2,000
Female14 – 182,000
Female19 – 302,000 – 2,200
Female31 – 502,000
Male9 – 131,800 – 2,000
Male14 – 182,400 – 2,800
Male19 – 302,600 – 2,800
Male31 – 502,400 – 2,600
Male51+2,200 – 2,400
Average daily calories needed in a survival situation. More info here.

It’s also indicated that these levels aren’t necessarily applicable to the individual based on current health, activity level and other factors and should be used only as a guideline.

Properly calculating specific required calorie levels takes a little more figuring and assessment, and other pertinent factors include overall activity level, climate, age, fitness and pre-existing health conditions.

Certain immutable factors like genetics and the overall efficiency of musculature and organs play a part as well. We will delve more into the problem of figuring all this out and the rest of the article below.

Minimum Calories for Sustainment

A particular interest of preppers is a concept that might be called the bedrock level of calories required for life.

If, as might be anticipated, you are forced to strictly ration food or have greatly reduced availability of food during any long-term crisis you are not going to be eating as much as you would normally, even in a survival situation when you have a fully stocked pantry. This is when the risk of starvation is at its highest.

University studies in the United States, including the prestigious UCLA Center for Human Nutrition, determined that an average adult can, in fact, starve to death when eating up to 1,000 calories a day, plus or minus.

Though that sounds like a lot of food under the circumstances, the math and the results do not lie. That is simply not enough calories to sustain all the many processes of biological life for a human being.

At that level of calorie consumption the body will begin consuming its fat stores for energy and they will be depleted relatively quickly, all things considered.

After fat stores are gone the body will begin consuming what you might call surplus muscle. These internally harvested calories will be used for cellular operation and the minimum required repair needs, though negative effects will be seen and felt.

The Negative Effects of Calorie Deficit

Your brain in particular is the largest overall consumer of calories and like any other organ when the brain is not fully fueled it will not operate at a high level.

Thinking will become more difficult and complex thoughts or planning might as well be out of the question. Emotionally, many people begin to “flatline” when badly underfed.

Beyond this, the loss of essential minerals and vitamins along with fiber will further impede bodily processes. Combined with a lack of calories overall the effects will be rapidly felt and quickly become devastating, surfacing as actual malnutrition.

Symptoms and effects will present as bad blood sugar swings, scurvy, constipation, bone fragility and a greatly reduced metabolism and energy levels to match. Your senses can be dulled or even shut down entirely depending on the severity of the starvation.

Joint and muscle pain will be constant, and once things get bad enough organ shut down will begin to occur, and this can make consuming enough food if food is found difficult or impossible resulting in a vicious cycle ending in death.

Activity Level is a Major Factor

As expected, the level of activity one undertakes is another major influence of calorie requirements with long periods of hard, arduous work requiring many more calories to keep your energy levels and nutritional demands in the black.

Attending the decidedly difficult work of survival, be it gardening, foraging, hunting, building, clearing rubble or anything else will place substantial demands on calorie requirements, totaling in the hundreds or even over a thousand additional per day.

Conversely, chilling out sitting down or resting on a bed, couch or cot while just existing means you’ll need far fewer calories for sustainment.

As a rule, if your survival situation or overall plan entails heightened or extremely strenuous levels of physical activity, plan on increasing nominal calorie requirements per person by anywhere from 25% to 40% as a rule.

Age and Overall Health Factors

Older folks do not need as many calories compared to younger folks, all things being equal.

Generally speaking, regardless of activity levels, past the age of 25 every decade that goes by will see the total level of calories required of a person reduced by 10% to 12%, or appx. Anywhere from 150 to 220 calories a day.

Regardless of any other attendant health issues, this is simply because our metabolisms slow as we age and the processes of life at the cellular level become less vigorous.

Coupled with reduced organ function and a general reduction in muscle mass we also have to contend with a brain that typically is not quite as quick or as agile as it used to be!

Other health factors are worth considering, with people who are very sickly requiring fewer calories than a healthy person, again owing to a reduced metabolism.

Similarly, a person who is healthy but is recovering from an injury may need increased calories as the body demands more resources for repairing a wound or other problem.

Some people suffer from more esoteric health conditions that could gravely increase or decrease calorie requirements in strange ways, and these should be accounted for on a case-by-case basis, the number of such conditions being so vast and varied that it is beyond the confines of this article.

Short-term Effects of Calorie Deficit

Make no mistake it is entirely possible to start even while eating regularly if calorie requirements are not met. At best, you’ll just be slowing the process.

However, as many preppers already know it is entirely possible to survive and even thrive while accomplishing all crucial survival tasks while on a reduced or greatly reduced calorie budget.

The human body has built-in reserves of energy in the form of fat and in a real crisis surplus muscle tissue. This can provide enough energy to keep the body fully operational even if energy levels, attitudes and performance are anything but optimal.

This means you don’t have much to worry about for quite a few days when calories are scarce or if you are trying to ration food for the short-term strategically.

Unfortunately, there is no way to negotiate with the brutal calculus of starvation: If you are not eating enough calories to sustain da ay today living regularly enough, you will eventually starve to death.

Frequently Asked Questions

The number of calories you need has to be balanced with proper nutrients, proteins, and carbohydrates. Here are some of the most common questions about daily calorie intake in survival situations.

Can You Live Off 600 Calories a Day?

No, only consuming 600 calories a day will not meet your calorie needs.

Recommendations for using it as a counter for weight gain is not ideal as it might not necessarily meet the dietary guidelines that someone like a registered dietitian would promote. In a survival situation your body would not last long without a significant boost in the daily caloric intake.

What’s the Minimum Calories Needed to Survive?

The bare minimum estimates for the amount of energy needed for long term health is around 1300 per person. Of course the exact science depends on the gender, basal metabolic rate (BMR), and activity level.

What Are Empty Calories?

Whole foods like beans, rice and whole grains provide more than just energy as they have minerals important to our bodily functions.

Empty calories mean things like sugar and enriched flours which provide energy but nothing substantial. These are fast burners and you’ll need replenishment quicker.

Will Emergency Foods Provide the Right Amount of Calories for a Survival Lifestyle?

Emergency foods provide quick energy in situations where you may not have the resources to make a proper meal.

They are lightweight and can get you through lean times but they are not good for your overall health as they tend to be loaded with salt and other preservatives.

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