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Winter Fueling Guide for Endurance Athletes

I know I'm not the only one who is clinging tightly to these weeks of Fall. Here in Santa Cruz, it "only" gets down to the high 30's and low 40's in the winter, which somehow feels FREEZING to me despite spending 20+ years in places that go through REAL winters. Anyway, my point is that temps are dropping everywhere, especially for my Midwest and Northeast clients, while many of my West Coast clients are heading to the slopes. So we need to chat about how to stay well fueled and hydrated during the colder months!


Sports nutrition tips for winter running and other endurance sports

How do cold temperatures and altitude affect hydration and fueling?

Cold weather can increase risk of dehydration and underfueling during exercise, and high altitude (>8,000ft) amplifies this risk further. These concerns apply to all active individuals, and particularly to endurance athletes given the duration of exercise.


  1. Cooler temps reduce thirst, which may decrease fluid intake. If using sports drink, this can lead to lower carb/salt intake.

  2. You may struggle with logistical challenges, like nutrition freezing. This may lead to reduced intake of fluid, salts, and calories. And as we know, that ain't good!

  3. Meanwhile, several things are going on to make your body lose MORE water. In the cold, blood flows away from the skin towards the center of the body to keep the organs warm, forcing the kidneys to filter more blood and make more urine (aka cold-induced diuresis). Similarly, at high-altitude, the kidneys react to drier air and control the thickness of your blood to carry oxygen, making more urine. And with less oxygen available, your breathing becomes faster and shallower, leading to greater fluid loss.

  4. Lastly, you still sweat in the cold, especially if bundled up. Drier air causes sweat to evaporate faster, so you just may notice it less. Don't be fooled!

All of this means that you must individualize and practice cold and sport-specific fueling strategies so that you stay well-fueled and hydrated in the outdoors! Don't "wing it" this winter - come up with a plan so you can feel awesome and have fun doing what you do.


Keep reading or download my FREE Winter Fueling Guide for Endurance Athletes.


Strategies to keep you fueled and hydrated this winter


1. Start ALL sessions well-hydrated:

  • For a rough estimate of your baseline daily hydration needs, take your body weight in pounds and divide by two to get number of ounces per day

  • Additionally, drink ~16-24oz if you have 2+ hours before exercise, or 8-16oz if you only have 1 hour before you start your session

  • If you're a heavy (sweat loss >1L/hr) and/or salty (sodium loss >1,000mg/L) sweater, consider pre-hydrating with sports drink or with salty foods plus water before exercise. This is particularly important before long and/or hard sessions.

2. Fuel before ALL sessions, regardless of duration:

  • For exercise <60-75min: Aim for ~30g carbs + 8-10g protein if you have 1-2hr before you go, or >60g carbs as part of a balanced meal if you have 2-3 hr before exercise

  • For exercise >60-75min: 60-90+g carbs + 8-10g protein if you have 1-3hr before you go, and then take 20-30g carbs (e.g. a banana or gel) 10-15min before you start

  • Individualize your carb intake: Consume 1-2g of carbs per kg of bodyweight as part of the recommendations above

3. Fuel/hydrate during longer sessions, even if not thirsty/hungry:

  • Do a sweat test in cold weather to individualize fluid goals during exercise. You can find detailed instructions on how to do this easy, at-home test in this blog post.

  • If you're not able to test, drink 12-28oz per hour for exercise >60min

  • For exercise lasting 1-3hr: Aim for 30-60g/hr of carbs

  • For exercise >3hr: Aim for 60-90g/hr carbs (plus 5-10g/hr protein for anything over 4-5 hours, and possibly some fat, as tolerated, )

  • Fuel/hydrate every 10-20min: At altitude, it is especially important to take smaller sips and bites for better GI tolerance.

  • If GI issues occur, slow down but don't stop intake and slow your pace.

4. Don’t let your nutrition or hydration freeze:

  • For gels, chews, pouches, and bars, keep them close to your core to stay warm

  • Instead of (or in addition to) the above sports products, try including foods that are less likely to freeze (e.g. PB&J, waffle, cookies etc)

  • Carry sports drink instead of water, which has a lower freezing point. If the one you like still freezes, try higher calorie sports drinks (e.g. Skratch Superfuel, Maurten 320 etc)

  • Insulate your fluids (e.g. bladder under jacket, bottles in wool socks, insulated hose) and blow black into tube after drinking so it doesn't freeze up


Download my FREE Winter Fueling Guide for Endurance Athletes


For practical fueling examples with visuals as well as ALL of the above info in a handy three-page guide, visit my Teachable School on-demand digital library and download my Winter Fueling Guide for FREE! You will also be subscribed to my monthly newsletter, which contains practical nutrition tips, podcast highlights, nutrition Q&A, recipes, subscriber-only discounts and more.


If you found this helpful, my 7-part self-paced course Peak Performance for Endurance Athletes is now available and will teach you how to crush your health and athletic goals. You can listen for FREE to module 1 in this podcast episode, and you can also visit the course page to watch a free video preview and read detailed course FAQs.


Questions? Email me at claire@eatforendurance.com.

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