How Many Calories per Day Do You Need to Survive?

How many calories a day does a person need to survive? It’s a serious question. Chances are if you’re on this website, you’re not looking for diet advice. You’re probably wondering how low you can go on calorie intake so you can stretch your food budget, and make the most of dwindling supplies.

It is grim to consider, but it’s a good idea: shortage, lack and loss of food may have you stretching already meager reserves to the breaking point for as long as you can.

According to USDA dietary guidelines, a relatively sedentary man aged anywhere from 26 to 40 years old requires 2,400 calories per day. A relatively sedentary female aged 26 to 50 years old will require 1,800 calories per day. In a survival situation, you may need up to 50% more calories to stay alive.

Other Factors

There are many other factors to consider when calculating calorie consumption besides age, gender, and activity level. Your genetic makeup has a certain effect on this; resting metabolism varies from person to person.

Existing muscle mass makes a big difference, and requires plenty of calories for repair and operation. Someone with greater muscle mass will always require more calories than someone with less.

Calorie “Floor”

Keep in mind the bigger survival picture if you are forced to cut food intake during a crisis. The UCLA Center for human nutrition discovered in their research that an average person eating fewer than 1000 calories per day is, in effect, starving.

That’s right, you can be gobbling down up to 1,000 calories and your body may as well be running on empty, and will react accordingly.

That means it’s going to be turning to fat stores first pretty easily to process energy supplies, and, after that, it’s going to turn on your muscles. It is because your body has immense energy requirements just to stay alive.

Your brain, organs, every single cell in your body need fuel constantly for operation and repair. At 1,000 calories or less, you’re already running at a deficit.

When you’re eating only around a thousand calories or less, you’ll notice your physical and mental performance start to suffer. Many of us will emotionally and mentally suffer even eating a fair amount above that, since much of our mental well-being is tied up in food intake.

Nutrition Concerns

Food isn’t just calories. Our food contains all kinds of necessary vitamins, minerals and fiber required for health and physical performance. As you cut calories, chances are you’re also cutting the percentage of those needed micronutrients.

This means even if you can sustain a low calorie diet for a long time, riding the needle you might say, you may yet incur the wrath of malnutrition.

Constipation, scurvy, the inability to regulate blood sugar, fragile bones due to lack of calcium and low metabolism may all be side effects of a low calorie diet deficient in ample nutrition.

You may be robbing Peter to pay Paul health-wise by trying to stretch your rations as long as you can.

Physical Activity Demands

Preppers who are working hard day in and day out to survive in the aftermath of a crisis will need more calories than a couch potato prepper holed up in a bunker. Strenuous levels of activity may increase your calorie demands upwards of 25%.

Someone who is extremely active for hours upon hours every day may have a 40% net total increase in needed calories compared to someone who is sedentary.

Aging Decreases Calories Needed

Aging diminishes your body’s need for calories. All things being equal, every 10 years a person ages will reduce their bodies calorie demand by anywhere from 150 to 220 calories a day.

This simply because our body’s natural life tempo slows down as we get older, in addition to things like reduced capability to repair, reduced performance of organs and tissues, and shrinking muscle mass, not to mention our gray matter slowing down a little bit.

If a computer isn’t humming along at high speed, it doesn’t need as much power!

Start the Clock

It is entirely possible to starve while still consuming a diet of real food if calories are insufficient.

Your body’s calorie demands are exactly that, demands, and those demands must be met. Survival on very low or no calories for a short period of time is possible thanks to your body’s built in reserves of energy in the form of fat and, in an emergency, muscle tissue.

While a few calories will prolong your lifespan compared to eating zero calories, the end result is still the same: death by starvation. It is a terrible, painful and grueling way to die.

Make sure you’re considering all factors before you decide to cut intake of rations to minimal levels. It might be a better idea to eat more calories so you can work harder and think smarter on a solution to the problem in the short-term.


Leaders in nutritional science have determined the most sedentary males will require around 2,400 calories per day to survive. Females require around 1,800 calories a day to survive, but keep in mind in a survival situation, you’ll need considerably more.

Use this information to plan your food stores accordingly, and take care of the plan for additional Calorie intake when activity levels must be sustained for a long time.

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1 thought on “How Many Calories per Day Do You Need to Survive?”

  1. Keep in mind that many food storage companies who claim “x days supply” are out and out lying to you. If you can find out the calories they actually provide, in some cases its only 800 calories per day. Which, as mentioned, is starvation. The only person who should be on an 800 calorie a day diet is someone morbidly obese, under the direct supervision of a doctor. And probably not even then.

    “Servings” are another way food storage companies “lie”, since that is not a quantifiable measure. One grain of rice is a “serving” if I’m greedy enough to say it is. Or a quart of rice is a serving if I’m a poor enough business man or generous enough to say it is.

    The standard for “life boats” seems to be 1200 calories a day, which may be “survivable” if you are laying in a life boat all day, but it’s not something you want to plan for long term, especially if you are planning to any exertions.


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