Eating Smart for Every Weather: Hot, Cold and Everything In Between

When the weather changes so does our nutrition requirements. The change in our environment puts different stresses on our body, and therefore our energy and fluid requirements will change. With the changes in weather across the year in the UK it is important to consider the different areas in which fuelling requirements may change.

Hot Weather

Hot weather isn’t optimal for exercise performance, and with heat waves hitting on race days after weeks of colder weather, it is important to understand how heat places extra stresses on the body and how you can adapt your fuelling strategies.

Dehydration can be a big worry in the heat, especially when exercising for long periods of time. A 2% reduction of body mass through fluid can cause noticeable decreases in performance. Athletes should hydrate well prior to the exercise, drink as much as is comfortable and practical during the sessions and rehydrate aggressively after the session in preparation for future sessions. If exercising for over an hour or losing large volumes of sweat adding electrolytes to water will help in replacing lost electrolytes.

In the heat, the body relies more heavily on carbohydrates for energy, shifting the substrate utilisation from fat oxidation to carbohydrate oxidation, when exercising for long periods of time. Muscle glycogen utilisation then becomes more important, therefore it is suggested that in hot environments, athletes ensure high carbohydrate foods are consumed to keep muscle glycogen stores topped up.

However, even though the body relies more heavily on carbohydrates, muscle glycogen oxidation increases, and exogenous carbohydrate oxidation decreases. This is because blood is directed to the skin to help cool the body down, and therefore is directed away from the gastrointestinal tract. So absorption rates are lower, but this energy is still required to delay fatigue. With this it is important that athletes keep high carbohydrate foods in the diet so muscle glycogen stores are not depleted.

We can however adapt to heat, although this won't change the nutritional considerations, it can help athletes feel more prepared and tolerate the hot conditions better.

Cold Weather

In the winter when the temperatures seem to drop overnight in the UK, it is important to know how to adapt to keep on top of our training.

In the cold our primary system to sustain core body temperature is through involuntary central nervous system induced shivering, which dramatically increases the use of muscle glycogen. So you may find you become more fatigued earlier than you normally would during exercise. To help prevent an earlier fatigue, consume high carbohydrate foods to help replenish glycogen stores. While on long runs you may find you need more carbohydrate supplements, so ensure to bring extra on your runs.

The risk of dehydration in the cold can also be as high as in hot temperatures. In the cold athletes are less likely to take on fluids and if wearing increased layers sweat rates can still be great. So in this weather, athletes are encouraged to take on fluids even if they don't feel like they need to. But adding electrolytes to the floods can help stimulate thirst, helping increase the uptake.

Unfortunately there aren't many ways to adapt for the cold, but if you are going to compete somewhere in a cold environment, it is a good idea to arrive a few days before the event for the body to make appropriate adaptations.

Final Word

Environmental conditions can place a variety of stresses on the body, and adapting nutrition strategies accordingly can be key to a successful training block, strong sessions, or even an optimal race day. By understanding how different weather conditions affect the body, athletes can adjust their approach in the way that works best for them.