So it's summer. Typically what do you think of when you think of summer? I think of sweating bullets 24/7, humidity (even though I don't currently live in a humid place) and I think of summery foods (i.e. Watermelon, BBQ, popsicles, etc.). This is what I grew up with because my family used to go spend days out in provincial parks, or near pools and these were just easy foods to have on hand. I'll be honest, because I know my parents are going to read this, they did their best to be "healthy," but some of my favorite food-related summer memories came when my parents didn't have time and ended up just grabbing chips and pizza instead of taking the time to create elaborate lunches. You're a kid, who doesn't love that. BUT this brings up an interesting conversation because as the weather gets warmer, we start moving away from soups, and comfortable warm dishes like lasagna, casseroles, etc towards cooler foods, but SHOULD we be doing this? Short answer: YES! Here's why we should consider changing up our diet as the weather changes.
Thermoregulation and Fluids
When the weather gets warmer as it does in the summer, we start to sweat more, and thus hot environments can dictate the performance of the gastrointestinal tract as it contributes to the pathophysiology of exertional heat illnesses (EHIs) and/or gastrointestinal complications that compromise the individual's capacity to address their nutritional goals and optimize thermoregulation among other things. What does this mean? When facing warm climates, our body turns into survival mode. We've probably heard of it doing this in a different context in the past with situations like an aggressive fast or something like this, but its overall goal is to ensure your body stays in a normal, sustainable core temperature range (~37C). Your body tries it's best using various mechanisms to try and lower your core temperature avoiding heat exhaustion (38.5C-40C) or worse. Over time, it shuts down bodily processes in order to utilize all of the body's stores of water to push to the skin and produce sweat. This sweat/water that comes out of sweat pores in the skin, is actually carrying heat out to the surface along with it. As it carries out heat, the water evaporates on your skin, cooling off the body and internally drying out the body of its water stores. That's just one use of water, BUT it's one really important part of setting yourself up for success in warm climates. The typical recommendations are that you should consider drinking 2L of water/fluids each day, however, I firmly advocate for doubling that in the summer, especially if you live somewhere humid where sweating is not as efficient of a process. Additionally, if you're an athlete, that number should likely be tripled (or more), dependent on your size, sport you play, intensity, local weather forecasts, etc. The best strategy is giving yourself a sustainable, achievable intake goal, and doing your best to work towards success in consuming enough fluids throughout the day. When it comes to exercise, that becomes a different ball game, below I will provide a strategy to address this.
Fluid/Electrolyte Intake Strategies Around Exercise:
During exercise, high body temperatures arise from excess heat storage due to sustained imbalance between internal heat production and heat dissipation at the skin surface. Heat is generated in large quantities as a by-product of elevated rates of metabolism, supporting muscle contractions. Simultaneously, heat can be gained or lost via convection and radiation, and dissipated through the evaporation of sweat. Long story short, your body uses sweat/ water in the body to cool the temperature of the skin down.
Pre-Exercise: Consuming 10 ml/kg BM fluid 1–2 hr prior to exercise can improve thermoregulation during constant workload exercise in the warmer environments
- this means that if I weigh 100kg, I would be consuming 1L of fluids 1-2 hours prior to exercise in order to ensure hydration in my body and optimized utilization of glycogen storage in the body during exercise.
During/Intra-Exercise: Opportunities to drink during exercise are often contingent on practicality and/or regulations associated with specific sports/ events. The benefits of fluid consumption during exercise continue to be debated, with contention surrounding the level at which dehydration begins to impair performance and how fluid replacement should occur. Generally, we know that at a point of 2% dehydration, athletes/competitors begin experiencing decreased sports/cognitive performance. What we want to do with our strategy, is to drink to replace sweat losses. If you know yourself to be a sweaty person, you will likely drink more, and less if you're not one who normally sweats. A good guideline for this is 250-500ml of fluids (preferably under 22C for increased palatability and thermoregulatory effects) per 1h of exercise.
Post Exercise: When quick reversal of moderate-severe fluid deficits is desired postexercise, it may be necessary to drink a volume of up to 150% of the net deficit to account for ongoing fluid losses during the hours of fluid re-equilibration. This means we want to drink 1.5x our water losses. Which for most of us, we're not weighing ourselves pre/post competition so it could be a very arbitrary number for recreational athletes, BUT it's a great guideline to consider. The simultaneous consumption of food is likely to facilitate post-exercise rehydration. When combined with voluntary food intake, the choice of postexercise beverage does not appear to influence the restoration of hydration status, but in the case of energy-containing fluids (e.g., sports drinks and milk-based drinks), it may lead to greater energy consumption than when water is consumed. Therefore, fluid and food intake during recovery should be considered in terms of overall nutrition goals
Should the Foods we eat change with the weather?
It's important before we address nutritional strategies, to start thinking about what our goals are. When it gets warmer, do we want to be leaner and worry about weight management, or do we want to make sure our body is primed for sports performance? Another thing you have to understand is, with warm weather, we are more likely to spend time outdoors, engaging in outdoor activities. What happens when we choose to do this, is we are more burning more calories and potentially increasing our NEAT (non-exercise activity thermogenesis) which is the energy we utilize outside of our planned exercise (in fidgeting, walking to get a cold beverage from the fridge, etc.). So if our goal is to lose weight for the summer, assuming we keep our nutritional strategy the same, we will likely have no issues losing a conservative amount of mass over the summer months. Assuming we are trying to put on mass, we can see this as being somewhat detrimental to our goals and should consider increasing the number of calories we consume on a regular basis. Athletic performance nutrition strategies can vary greatly in warm environments from sport to sport, but below we will address some solid guidelines that you can take with you to improve your nutrition to keep your body comfortable, in an optimal temperature range, and boost your sports performance.
Practical Nutritional Strategies in Warm Climates for Athletes:
While there may be a million different ways to change up nutrient strategies for athletes, consuming adequate calories for peak performance is still the most important goal for the athlete. Additionally, there are cooling strategies the athlete can take on in order to reduce the effects of thermal discomfort from the heat. Some strategies include drinking cold beverages, like iced slurries/slushies, or consuming ice cream to bring the internal temperature down and either increase hydration or add to the total caloric reservoir, respectively. These strategies are important in order to optimize outcomes in the context of sports performance. Another nutrition strategy that alters thermal sensation is the use of L(-) menthol. Menthol is a cyclic terpene alcohol found in mint leaves, which activates oropharyngeal cold receptors and increases the threshold temperature for their activation, creating a feeling of coolness. Menthol can be applied externally to skin or clothing as a gel or spray, but the most effective method is oral ingestion in the form of mouth rinse or an aromatized beverage. Again, the goal of consuming the mint is to bring the feeling of coolness/ to lower the body temperature in order to decrease the rate of perceived exertion of the athlete which should increase performance potential.
Hopefully, you enjoyed this quick read about nutrition in warm climates. I hope to keep more consistent content with regards to nutrition, and specifically sports nutrition coming your way! Please, if you enjoy this content, or have something you'd like me to research and cover... let me know! As always, some of the resources are listed below in references for your perusal.
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Hamouti, N., Fernandez-Elias, V.E., Ortega, J.F., & Mora-Rodriguez, R. (2014). Ingestion of sodium plus water improves cardiovascular function and performance during dehydrating cycling in the heat. Scandinavian Journal of Medicine & Science in Sports, 24(3), 507–518. PubMed ID: 23253191 doi:10.1111/sms.12028
McCubbin, A. J., Allanson, B. A., Caldwell Odgers, J. N., Cort, M. M., Costa, R..S., Cox, G. R., Crawshay, S. T., Desbrow, B., Freney, E. G., Gaskell, S. K., Hughes, D., Irwin, C., Jay, O., Lalor, B. J., Ross, M..R., Shaw, G., Périard, J. D., & Burke, L. M. (2020). Sports Dietitians Australia Position Statement: Nutrition for Exercise in Hot Environments, International Journal of Sport Nutrition and Exercise Metabolism, 30(1), 83-98. Retrieved Aug 18, 2020, from https://journals.humankinetics.com/view/journals/ijsnem/30/1/article-p83.xml
Peier, A.M., Moqrich, A., Hergarden, A.C., Reeve, A.J., Andersson, D.A., Story, G.M., . . . Patapoutian, A. (2002). A TRP channel that senses cold stimuli and menthol. Cell,108(5), 705–715. PubMed ID: 11893340 doi:10.1016/S0092-8674(02)00652-9
Sawka, M.N., Burke, L.M., Eichner, E.R., Maughan, R.J., Montain, S.J., & Stachenfeld, N.S. (2007). American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine & Science in Sports & Exercise, 39(2), 377–390. PubMed ID: 17277604