Calories and protein in an emergency: the basics

During digestion the body breaks food down into small building blocks and “burns” them slowly in the cells – without a flame, but with a similar result: energy is released, part of it as heat. As a common approximation, carbohydrates and protein provide about 4 kcal per gram and fat about 9 kcal per gram. That is why nuts, oil or hard cheese are so valuable when space and weight are limited.

A large part of the energy is used even at rest: for the heartbeat, breathing, the brain and body heat. On top of that comes everything you do – walking, carrying, shovelling snow. In the cold the body also has to heat itself, for example by shivering. So needs depend strongly on body size, age, activity and temperature.

Protein is different from the other two: the body uses it mainly to maintain muscle, skin, blood and immune defences. If more is eaten than needed, it is broken down, and the waste products have to be excreted through the kidneys with water. That is why a lot of protein is unhelpful when water is short.

For planning you do not need an exact calculation, just a rough overview. Following the Sphere Handbook, humanitarian organisations plan with an average of 2,100 kcal per person per day for a whole population. That is an average: a small child needs less, a tall adult who does hard work or is cold needs considerably more.

For protein, WHO, FAO and UNU give a safe intake for healthy adults of around 0.8 g per kilogram of body weight per day. An adult weighing 70 kg would therefore need about 56 g a day. This amount is easy to reach with pulses, tinned fish or meat, nuts, milk powder or long-life dairy products.

At least as important as the numbers is the question: will the food actually be eaten? Under stress and uncertainty many people eat less, especially when food tastes unfamiliar. A stock of familiar food that everyone likes and tolerates is therefore worth more than a theoretically perfect stock that stays untouched.

Take a package and find the “kcal per 100 g” figure on the label. Multiply it by the weight of the package in grams and divide by 100 – that is the energy of the whole package. A 500 g pack with 350 kcal per 100 g, for example, contains 1,750 kcal.

Add up the main parts of your stock this way and divide the total by the rough daily needs of all the people. The result is roughly the number of days the stock will last. This figure is a guide, not a promise – but it shows at once whether you are covered for three days or for two weeks.

Then check the mix: is there enough protein? Is there shelf-stable fruit and vegetables, for example from jars, tins or dried? Is there something that can be eaten without cooking? And is there enough water for everyone according to your authority's recommendation?

Infants, young children, pregnant and breastfeeding people, older people and the chronically ill – for example with diabetes or kidney disease – have their own needs. The averages do not apply to them. Agree their stock and emergency diet with a doctor, midwife or dietitian while everything is calm.

Allergies and intolerances do not disappear in an emergency. Popular stock staples such as nuts or peanut butter are among the common allergens. If someone in the household is affected, deliberately plan alternatives and clearly label dangerous foods.

When water is short, do not eat large amounts of high-protein or very salty food, because both increase fluid needs. When food is short, saving energy – resting, staying warm, drinking enough – helps more than hard work. This entry does not replace nutritional advice and makes no statements about longer fasting.

The reference values come from international expert reports by FAO, WHO and UNU. They describe averages for large groups and include safety margins – they are not calculated for individual people. For a household the principle is entirely sufficient.

A common misconception is that an emergency stock must consist mainly of special food. In fact, authorities recommend food you eat anyway, in somewhat larger quantities. Once you have roughly worked through your stock, you know where the gaps are – and can close them calmly on your next shopping trip.