Humans, as warm-blooded mammals (better known as Homeotherms), run best at a set internal temperature. This means our system tries to maintain a consistent temperature independent of what the external environmental temperature may be. In our case, we are Endotherms – which means we internally generate our own heat, in comparison to an Ectotherm, which is reliant on external factors to regulate their body temperature.
While an Endotherm will utilise external sources to regulate temperature (sitting in front of a fire, taking a cold plunge), the chief benefit of being an Endotherm is that we are able to withstand extremes of temperature ranges by internally self-regulating. For example, we can drop heat through sweating, creating convection of heat. However, this article will focus on the creation of heat. We have two primary methods of creating heat in our bodies, muscle contraction (which can present itself as shivering) and as a result of the process of metabolism.
Because we use metabolism (digestion) as a source of heat, we require a lot more food to maintain the system. In addition, the base rate of metabolism is going to be up to six times as fast in an Endotherm (warm) than in an Ectotherm (cold) of the same size.
The short of it – cold? Eat something!
The human body when feed, immediately starts processing that food through the process of digestion, metabolising that food into energy that we can use. A beneficial product of the process is also heat, which we can use to get warm when we are cold. If the system doesn’t have any food to digest then we are robbing ourselves of one of the easiest and most effective ways of firing up our internal heater.
If you are hungry you are also going to get cold.
Eat before sleep
Having a good meal before climbing into the sleeping bag for the night is a very good suggestion. Regardless of the temperature, if you have been tramping/stalking/exercising the body all day you need to replenish your energy stores – charge the battery and make sure you are ready to go the next day.
In the cold, this becomes even more important because what you eat before you go to sleep is going to have a direct influence on how warm or cold you are going to get during the night.
Sleeping bags and clothing don’t generate heat. They insulate. They keep the heat you are generating trapped and close to the body, helping regulate that important core temperature. It doesn’t matter what rating your sleeping bag is, if you aren’t generating heat you will not be warm.
What to eat
Well, if it’s something warm you are going to get double the benefits. Not only are you literally supplying heat to the body, but you are also fueling it and enabling the process of digestion to also create heat. If it’s cold the benefits of a good hot meal are both moral and physical. That’s why many suggest that a cup of tea or hot chocolate are ideas before tucking in – it’s one last load of heat before starting to trap your expenditure through your sleep system.
However, certain foods are better – and essentially the harder (requires more energy) they are to digest the better. This means extended heat creation; and while at some point you are going to have to start expending energy digesting them than you get back (thermogenesis), if you are really cold it could mean making it through the night without going into a state of hypothermia.
Protein requires the most calories to digest, that, in addition, Fats and complex carbohydrates are what you are looking for. It’s suggested that certain spices can help stimulate the generation of heat. A hot curry on brown rice, with a pile of ginger, coconut oil and cinnamon is an awesome combination to generate internal warmth and continue to do so throughout the night.
That’s nice. But I have lost my pack.
At a pinch – a One Square Meal is also a really good backup option. Lots of carbs, not the quickest to digest, great for generating heat. That is why it is important to keep some kind of food in your emergency kit.
While it is also a good morale booster the reality is you are unlikely to die of starvation if you miss a meal, or two. However, if you find yourself caught unprepared and having to stay a night out in the bush some form of food that you can use to fuel the digestion system and therefore the generation of heat is going to be of massive benefit. Get yourself insulated from the ground (conduction), climb into an emergency bag (convection and reflection) and eat that bar (generation). It’s going to maximise your ability to generate and trap that heat. I won’t promise you are going to be toasty warm, but you will be a lot better than going to bed on an empty stomach.