All over the UK, we are having a heatwave of unprecedented proportions at the moment. With this heatwave comes refreshing water activities, ice cream and cold beverages. If asked, many of us would agree that those ice creams and cold drinks are refreshing, but the real question is, do they really cool us down?
To explore this idea, we need to know more about how the body controls our temperature. Maintaining an optimal body temperature is called thermoregulation, which involves a careful balance between losing and producing heat.
Humans are warm-blooded, which means we can control our body temperature independent of our environment. However, our bodies often produce heat as a by-product because of our internal chemical processes, known as our metabolism.
So how does this all work?
Metabolism is a critical process to keep our bodies working correctly. Most will commonly know of it for the digestive processes involved in the breaking down of nutrients in our food, then the absorption and transportation of these nutrients to our blood cells. Finally, also for converting into energy needed for any form of physical activity.
This process generates heat, which can be helpful when it’s cold, but when it’s as hot as it has been these last few weeks, that isn’t so good and is something we want to avoid. So it may seem like a good idea to introduce something cold, say ice cream, into our stomach, which could reduce these temperatures; the cooling effect it may give off is quickly replaced with the heat created by our digestive processes as they break down the nutrients in the ice cream. In addition, science shows that eating calorie-dense foods leads to a raising in our body temperature.
So sadly, ice cream is not always the best option to cool us down, but what about cold drinks? There is a slight change in our body temperature when we digest that cold drink, but this is only for a short time; this can depend on how much drink it is and the calorific content of the drink.
If it’s a small drink, it will quickly lose its cooling effect as it will get warmed up by your bodies surrounding organs. Also, drinking a lot of cold liquids can cause blood flow to slow, meaning your blood will transport heat less effectively.
Finally, any form of drink that is high in calories, such as fizzy drinks or fruit juice, can also have a similar effect as ice cream, kick-starting our metabolism into overdrive after ingestion, meaning a rise in body temperature.
But Dave… I’m sure I feel cooler…
That cooling feeling you get from drinking cold drinks likely can be explained by its ability to rehydrate you. Your body will try to lose any excessive heat by moving it away from your vital organs to the surface of your skin, where it can be released into the environment through convection and radiation.
For this process to work, the ambient temperature will need to be lower than our bodies’ temperature, or it means the opposite can happen, and the heat can transfer to our bodies. For example, the heat that radiates from our sun on a hot sunny day.
The most effective way for our bodies to lose excess heat is via sweating. When our brain detects that our core body’s temperate is rising, it responds by sending commands to our sweat glands across our body to stimulate and produce sweat.
This sweat will then evaporate from our skin service, meaning the skin will cool down (sometimes called evaporative cooling). In addition, any blood in our arteries close to our skin will then be cooled in this process which can lead to a reduced core temperature.
Most adults can lose up to a litre of sweat every day, but this is on an average day. However, in hot environments, this heatwave can increase to almost a litre and a half AN HOUR! A huge difference, clearly showing the need to keep our bodies hydrated during hot weather as, without this, we cannot produce sweat.
So is there a different way we can approach this?
So what about alcohol? Many will reach for a cold beer or chilled alcoholic drink on these hot summer days in the hope of cooling themselves down. Sadly though, this can hinder rather than help, as alcohol is a diuretic, meaning that drinking them can make your body lose water, reducing sweat production and its cooling effects.
I know many would not like the idea of a warm drink during this warm weather, but it may be an excellent way to keep you cool. It may seem counterintuitive, but drinking tea or other hot drinks can cause the receptors in your mouth and throat to trigger, leading to a sweat response. This will allow your body to cool down withing the need to drink a lot of hot drinks. So maybe even having a hot drink nearby and having small sips now and then may help!
Most spicy food also has active ingredients that can have the same effect, triggering your sweat response and allowing you to cool down. It’s one of the reasons why these dishes are so popular in warmer climates.
So, in conclusion, while those cold treats may be comforting and refreshing, a better way of cooling yourself down is to spice things up and get your sweat on. Most notably, during this heatwave, though, it to rehydrate!