Eating & Drinking during Exercise

Do I need to eat or drink during exercise?

How much you need to eat or drink during exercise depends on many factors including the intensity and duration of the training session or event, goals of the session and body composition objectives. In general you won’t need extra fuel (carbohydrate) during exercise sessions lasting less than ~60 minutes (and possibly up to 90 minutes if the intensity of the session is low). However, if your training session or event is longer than 60-90 minutes topping up with extra carbohydrate during the training session can help to:

  • Maintain blood glucose levels to fuel your muscles and brain during exercise
  • Get the most out of your training session by sustaining intensity for longer

Fluid needs during exercise are highly individualised and will depend on your unique sweat rate which is determined by genetics, body size, fitness levels, intensity and duration of the training session and of course the temperature and humidity that you’re exercising in. For short, low intensity exercise sessions in cool weather you may only need a small amount of fluid, if any, during the session. For longer and more intense sessions or events, particularly if it is hot and humid you may need to be more proactive with your fluid intake to avoid becoming dehydrated. An Accredited Sports Dietitian can help you determine your individual sweat rate.

What can happen if I get my nutrition plan wrong during exercise?

Getting your nutrition plans wrong during training or an event usually means that you don’t optimise your potential during the session. Failing to fuel or hydrate correctly during exercise can result in:

  • Earlier onset of fatigue (commonly referred to as “hitting the wall” or “bonking”)
  • Reduced speed, especially during repeat efforts
  • Reduced endurance
  • Poor concentration and decision making
  • Skill errors
  • Gut upset
  • Suboptimal body composition

How often should I eat or drink during exercise?

There’s no one size fits all plan for eating and drinking during exercise but as a general guide:

  • Sessions or events shorter than 60-90 minutes (e.g. 5-10km run, sprint distance triathlon, criterium cycling race) – typically no need for extra carbohydrate during the session. Small amounts of fluid may be required depending on sweat rates.
  • Sessions or events lasting longer than ~90 minutes (e.g. marathon, Olympic distance triathlon, many team sports) – likely to be benefits to topping up your fuel (carbohydrate) stores during the session. The exact amount required will depend on the duration and intensity of the session as well as individual factors such as tolerance and taste preferences. Potential for dehydration during these longer sessions, particularly if the weather is hot and humid, however the volume of fluid needed will depend on your individual sweat rate.
  • Ultra-endurance events longer than 4 hours (e.g. Ironman, 100km trail running events, ultramarathons, 150km cycling challenge) – these types of events have unique fuelling and hydration requirements as not only do carbohydrate requirements need to be met but logistics (e.g. managing check points or carrying food and fluid over the course) and other challenges such as poor appetite and flavour fatigue also need to be considered.
  • Multi-day events (e.g. cycling tours or team sport tournaments) – your body’s stored fuel (glycogen) stores will gradually deplete over consecutive days of competition so it’s important to keep them topped up with carbohydrate during and between sessions to avoid unwanted fatigue. Without sufficient fluid there is also the potential for dehydration to carry over to subsequent days of competition, which has the potential to negatively impact performance

What should I eat during exercise?

Everyone is different in what they like to eat (and what sits comfortably in their stomach) during exercise but in general foods should be:

  • Rich in carbohydrate to top up your fuel stores
  • Low in fibre, especially if you have issues with your gut upset or feel very nervous
  • Easy to digest – avoid foods overly high in fat as these are slow to digest
  • Familiar – practice your options in training and don’t try anything new on event day!

There’s no one “best” option for what to eat during exercise and it will depend on what your individual preferences and requirements are but here’s a few ideas to get you started.

  • Simple sweet sandwiches (e.g. jam, honey)
  • Simple savoury sandwiches (e.g. peanut butter or vegemite)
  • Bananas
  • Muesli bars
  • Fruit buns
  • Carbohydrate gels
  • Sports energy bars

What is the best fluid to drink during exercise?

The ideal fluid during exercise depends on your goals. If you are using fluid mainly to hydrate for the session than water or electrolyte drinks are a good option. If you also need a source of fuel then sports drinks can be helpful as they contain both carbohydrates and fluid to help hydrate and fuel your body at the same time.

For more information on this or other sports nutrition topics, subscribe to our newsletter or book to see an Accredited Sports Dietitian.