Why Can Our Appetite Change With The Weather?
Article by Abi Woodliffe-Thomas
The reasons as to why we eat are plentiful, but have you ever considered the science behind our hunger changing as the seasons change and how to fuel our bodies, in day to day life and exercise, as we step into Spring?
Food's overall warming effect is known as thermogenesis. Your body generates about 10 percent more heat after eating than on an empty stomach. Eating not only provides fuel, but also increases heat production (warmth).
The science behind why we change what we eat when the seasons change
At its simplest level, the variation in appetite is a function of our bodies needing fewer calories to maintain optimal body temperature. When the weather is hot, the difference between our body temperature and the outside temperature is less, meaning less energy is required to maintain homeostasis (1). Conversely, when it’s cold, our bodies must work harder to stay warm meaning we take in more food to help fuel that process.
Do we need to change what we eat when we exercise in different seasons?
Prolonged bouts of strenuous exercise, particularly if performed without carbohydrate intake and/or adequate energy intake, may compromise your body’s immune system. In addition, heavy exercise leads to the release of high levels of cortisol which reduce your body’s ability to fight infections (5).
Reaching for hearty home comforts is nature’s way of strengthening and supporting your immune system. These hearty home comforts make the perfect post workout meal when training in the cold - not only helping to maintain bodily homeostasis, but also packed full of proteins, carbs, and fats, they are a brilliant recovery meal. Likewise, loaded salads and lighter meals are more appealing during the spring/summer months (3). That’s not to say that in the warmer months of the year we cannot enjoy these hotter lunches and dinners and vice versa. We can of course still include and savour these dishes in our diets all year round to help support our immunity and fuel our workouts. It’s important to remember that a healthy diet is all about balance and variety so mixing up the meals we eat is a great way to maintain this.
What about hydration - do we need to alter this too?
Alongside a variation in nutrition as the seasons change - hydration is equally as important in the colder months. When you are cold, your thirst response gets blunted, and you often become dehydrated faster that you may think. Excessive water vapour lost through breathing, as well as general sweat lost from exercise, can reduce hydration levels with the absence of the warning signs prompting us to drink water (6).
In the summer months, our thirst response is more recognisable, and water is often also consumed through food sources like fruits and vegetables accounting for around 20-30% of our fluid intake, and there are some that contain more water than others (4).
Ice-lollies and ice cream might seem like natural choices on a sunny day, but the cooling effect is often short-lived. Cold foods cause an increase in temperature as the process of digestion is heat-generating. In other words, the rapid cooling initiated by cold food and drink causes your body to over-compensate and raise your core temperature. That’s why you may end up feeling hotter than you were before!
Drinking something hot on a sunny day might feel like the least appealing thing to do, but warm drinks can help regulate your body temperature in the opposite way to above. Hot drinks make your core temperature rise and that makes your body want to cool down, so you sweat more to lose heat through your skin (4).
So, as we step into spring and the days get longer, be sure to remain fuelled and hydrated to help training, recovery, and bodily homeostasis.
This blog post was written by Abi (@Happetitie_) . Abi is a Physiology and Nutrition masters student at Loughborough University hoping to become a performance nutritionist. Currently getting involved with four internships, work experience and further reading, alongside her studies, Abi cannot wait to help athletes gain that extra 10% in their sporting performance through a food first approach. Abi is an ex-International Acrobatic Gymnast and sport is a huge part of her life. Learning at Loughborough University has been an amazing opportunity for her and she cannot wait to put all the theory into practice and apply it within the sporting world!
References:
(1) Hardy, J.D., 1961. Physiology of temperature regulation. Physiological reviews, 41(3), pp.521-606.
(2) Herman, C.P., 1993. Effects of heat on appetite. Nutritional needs in hot environments: applications for military personnel in field operations, pp.187-214.
(3) Morrison, J., 2015. Why your appetite goes up when the temperature drops, and what to do about it. By Dr. Jeffrey Morrison, M.D.. [online] Morrison Health. Available at: <https://www.morrisonhealth.com/why-your-appetite-goes-when-temperature-drops-and-what-do-about-it/> [Accessed 20 March 2022].
(4) Nutritionist, K., 2019. How to eat in a heatwave | BBC Good Food. [online] Bbcgoodfood.com. Available at: <https://www.bbcgoodfood.com/howto/guide/how-eat-heatwave> [Accessed 20 March 2022].
(5) Nieman, D.C., 1994. Exercise, infection, and immunity. International journal of sports medicine, 15(S 3), pp.S131-S141.
(6) Marriott, B.M. ed., 1993. Nutritional needs in hot environments: Applications for military personnel in field operations.