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Um Bungo: What to eat and drink when humidity is all around

It’s going to be difficult to meet your fluid needs but try to drink little and often.

Um Bungo: What to eat and drink when humidity is all around


Last updated: 02-Mar-16

Written by Sports Dietitian Rin Cobb

Ultra running is becoming increasingly popular and as such races are cropping up all over the world, each with their own unique challenges. Jungle ultras are no different and with the Costa Rican Coastal Challenge (TCC) next month, here we explore the nutritional challenges you’ll likely face along the way.

Asia, Africa or the Americas, whichever jungle you maybe running through, they all have a common challenge; heat and humidity. Combined, these may not only affect your running performance but your health too through varying degrees of heat illness including heat exhaustion, exertional heat stroke, heat cramps and heat syncope (fainting). Unsurprisingly, both dehydration and hyperthermia are the key culprits. The human body, being highly adaptable as it is, can acclimatise to heat however this takes up to 2 weeks. Unless you’re already living and training in a similar climate, many of you will only have a few days in the country before starting a race so won’t have the necessary time to acclimatise fully.  Despite this, many of you have and will go on to successfully complete ultras in both hot and humid conditions so whilst acclimatisation would be the ideal preparation, when it’s not possible you do the best you can and this is where eating and drinking adequately makes the difference.


There is no one size fits all recommendation with regards to how much you should drink when running so you need to try and work out what your own body needs under different conditions. Some of you may already estimate your own sweat rate but if not here’s how to go about it:

Estimating fluid loss/sweat rate:

  • Weigh yourself after emptying bladder just before going for a run
  • Weigh yourself after emptying bladder when you finish
  • Difference in weight plus any fluid drunk during run

Example: 0.5kg loss in 1hr run + 500ml fluid intake = 1kg/L sweat loss/hour

If you can work out what your fluid losses are then this will give you a guide to how much you need to replace per hour. Additionally it can also help you work out how much to drink after you’ve finished a run, which when you have a limited amount of time to recover and replace fluids should be 1.5 times your losses to account for regular toilet trips.

Of course, this whole process may not be so practical under jungle conditions but you could certainly use this method whilst training to give you a baseline. A more crude way to see if you’re well hydrated during a race is to check the colour of your pee. The lighter it is, the better hydrated you are and aiming for straw-coloured pee is desirable. 

Ultimately it could be argued for a multi-day jungle ultra, it’s going to be difficult to meet your fluid needs but try to drink little and often as the gut can struggle to absorb and use large volumes of water in one go.


Sodium is the main electrolyte lost through sweat, whilst potassium, magnesium and chloride are lost in much smaller quantities. You’ll generally find sodium added to sports drinks but this isn’t only to replace losses but also helps the gut absorb fluid better and can make you feel more thirsty, thus encouraging you to drink more. Electrolyte tablets have become popular in recent years as they can be used on their own or in addition to sports drinks and for a jungle ultra should certainly be on your kit list. As coconuts are in abundance in Costa Rica, specifically for the TCC, coconut water is another way to top up your electrolytes or could even be mixed with fruit juice for a jungle-made sports drink. 

Contrary to current healthy eating messages, adding salt to your meals whether you’re self-sufficient or being catered for is another way to help replace losses particularly when racing day in day out. You may even get the chance to sample a local Costa Rican fruit called the Red Jocote, which apparently is best eaten with salt so they provide that too.


As the temperature rises, so will your bodies use of carbs for fuel. Even for a catered race like the TCC taking some carby snacks, which you’ve tried and tested during training is a good idea. Of course you may well be able to literally pick and choose from the abundance of seasonal fruit around you such as melons, bananas, papayas or even try a sapodilla, a very sweet grape like fruit for those low blood sugar moments.

Using sports drinks powders with added electrolytes is a practical all in one option which provides carbs for fuel, fluid to rehydrate and electrolytes to replace losses and help your body absorb the fluid better; et voila! Just be sure to check powders have enough sodium if not using additional electrolyte products with the optimal amount being 0.23 – 0.58g sodium per litre or 0.57 – 1.45g salt per litre.

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