Most running nutrition advice is written for mild conditions – a temperate morning, moderate effort, predictable sweat rate. But if you train year-round in a climate like Canada's, that's a fraction of your actual running life. Summer humidity and winter cold each place distinct demands on your body, and ignoring them means your fueling strategy is working against you for a good portion of the year.
The adjustments aren't dramatic. But they are real.
Running in the Heat
What Actually Changes
You track your miles.
We'll handle the meals.
Heat does two things that matter nutritionally. First, it significantly increases sweat rate. In hot and humid conditions, sweat losses during sustained running can reach 2 to 3 litres per hour – far beyond what most runners plan for. [1] Second, heat shifts your body toward burning more carbohydrate relative to fat. The same pace that burns a moderate amount of glycogen in cool conditions depletes your stores faster in the heat, because metabolic stress compounds the thermal stress. [1]
The practical result: you need more fluid, more electrolytes, and your carbohydrate availability matters more than it would on a cooler day.
Fluid and Electrolytes
In the heat, the fluid and electrolyte side of fueling takes priority over everything else. Even modest dehydration – 2 percent of body weight – meaningfully impairs cardiovascular function and performance in warm conditions, and the threshold arrives faster than it does in the cold.
Sodium is the key electrolyte. It's lost in the highest concentration in sweat, it's necessary for retaining the fluid you drink, and replacing it prevents the dilutional effect that plain water creates when consumed in large volumes. For runs over an hour in the heat, a homemade electrolyte drink or any sodium-containing fuel source is more effective than plain water:
Maple Lemon Electrolyte Drink
Carbohydrates in the Heat
Because glycogen depletes faster in the heat, starting well-fueled matters more. A proper pre-run meal with carbohydrates is not optional on a hot summer long run. During the run itself, the same carbohydrate targets apply – 30 to 60 grams per hour for most recreational runners – but erring toward the higher end of that range is sensible when conditions are hot.
One complication in the heat: appetite is often suppressed and the thought of eating a gel or chew feels less appealing. Liquid carbohydrates – sports drinks, diluted juice, or an electrolyte drink with carbohydrates – are often better tolerated than solids when it's very hot. Worth experimenting with in training before race day.
Recovery in the Heat
Rehydration after a hot run requires more attention than after a cool one. The goal is to replace roughly 150 percent of fluid lost – so if you lost an estimated 500ml, aim for around 750ml in the first hour or two after finishing. Including sodium in that recovery fluid or food helps your body retain what you drink rather than excreting it.
These recovery meals work well after hot summer runs, providing carbohydrates, protein, and fluid alongside some natural electrolytes:
Salmon Poke Bowl
Tart Cherry Smoothie
Running in the Cold
What Actually Changes
Cold running has a different set of problems, and they're more subtle. The most significant is that cold suppresses the thirst mechanism. Research shows that cold environments reduce voluntary fluid intake even when the body is meaningfully dehydrated – by as much as 40 percent in some studies. [2] You can finish a cold long run significantly under-hydrated without ever feeling thirsty.
Cold air is also very dry. Every breath you exhale releases moisture, and over a two-hour run in dry winter air, respiratory water losses add up to more than most runners account for.
The second issue is energy. Cold-weather exercise can increase energy expenditure, particularly when you're inadequately dressed and your body is working to maintain core temperature. But appetite during exercise in the cold is often suppressed – physical activity blunts hunger signals, and the cold compounds this. The result is that runners frequently finish cold runs in a meaningful energy deficit without realising it. [3]
Hydration in the Cold
Drink on a schedule rather than to thirst in cold conditions. Your thirst signal is unreliable. The same rough guideline applies – roughly 400 to 600ml per hour on runs over an hour – but you may need to remind yourself to drink it rather than waiting to feel the urge.
Warm fluids are easier to consume in very cold conditions and have the added benefit of not chilling you from the inside. A thermos of warm diluted sports drink, warm broth, or warm water with a pinch of salt is a practical cold-weather solution that many experienced winter runners use.
Fueling in the Cold
Your carbohydrate needs during a cold run are similar to temperate conditions – the per-hour target doesn't change dramatically for most recreational runners. What changes is the practical challenge of actually eating while cold.
Gels and chews can become stiff or unpleasant in very cold weather. Dates, homemade energy bites, and rice cakes tend to hold up better texturally. Keeping fuel in a pocket close to your body – rather than a vest pouch exposed to the air – prevents it from freezing or becoming unmanageable.
Medjool Date & Sea Salt Chews
Recovery in the Cold
Post-run recovery in the cold has one particular risk: under-eating. Because appetite is suppressed during cold exercise and the cold itself can blunt hunger in the immediate aftermath, runners often delay or skip their recovery meal. Combined with the energy deficit accumulated during the run, this compounds the recovery hole.
Warm recovery foods are more appealing after cold runs and have a genuine physiological advantage – eating generates heat through thermogenesis, which helps you warm up. Soups, stews, warm grain bowls, and porridge all fit well here. The nutritional content matters as much as the warmth: carbohydrates to replenish glycogen, protein for muscle repair, and fluids to address the dehydration you likely didn't notice building during the run.
Spicy Cabbage & Lentil Recovery Soup
Coconut Curry with Rice
The Practical Summary
In the heat: hydration and electrolytes take priority, carbohydrate demand increases, liquid fuels are better tolerated, and recovery rehydration requires deliberate effort.
In the cold: drink on a schedule because thirst is suppressed, keep fuel accessible and warm enough to eat, eat your recovery meal even when you don't feel hungry, and make it warm.
The fundamentals of fueling don't change with the seasons. The execution does.
Fuel.fit tags every recipe by training context – pre-run, during-run, and recovery – so you can build a fueling routine that works whatever the season.
Sources
[1] Burke LM. Nutritional needs for exercise in the heat. Comp Biochem Physiol A Mol Integr Physiol. 2001;128(4):735-748.
[2] GU Energy Labs. Cold weather hydration: why thirst fails you in winter. 2017.
[3] Karl JP, Margolis LM, Rood JC, et al. Performance nutrition for cold-weather military operations. Arct Antarct Alp Res. 2023;55(1).
