Hydration, Heat and Hunger: What You Need to Know About Appetite in Wa

As summer arrives in the UK and across Europe, many people naturally become more active, spend more time outdoors, and adopt lighter eating habits. But there’s another seasonal shift that often goes unnoticed. How heat and hydration levels can influence our hunger cues, and ultimately, our approach to weight management.

Understanding the physiological link between temperature, fluid intake, and appetite can help you make more informed and intuitive choices during the summer months, whether you’re at home or travelling across sunnier parts of Europe.

Here’s what you need to know:

1. Dehydration Can Mimic Hunger Cues

One of the most common reasons people feel hungrier in summer, ironically, isn’t due to a lack of food, but a lack of fluids. Mild dehydration can lead to sensations that closely resemble hunger: fatigue, headaches, irritability, and a gnawing feeling in the stomach.

A study published in Physiology & Behaviour (2016) showed that inadequate hydration can influence appetite regulation, potentially leading to unnecessary calorie consumption when the body is actually signalling for water, not food. This is especially relevant in warmer climates or during holidays when regular routines are disrupted, and alcohol or caffeine intake increases.

Tip: If you’re feeling unexpectedly hungry, especially between meals, try drinking a glass of water and waiting 15–20 minutes before reaching for a snack. You might find the craving disappears altogether.

2. Heat Naturally Suppresses Appetite (To a Point)

It’s not just your imagination, you often eat less during heatwaves. That’s because high temperatures cause the body to divert blood flow to the skin for cooling, reducing blood flow to the digestive system and naturally lowering appetite.

Research from the Journal of Nutrition (2013) supports this, showing that thermoregulation and digestion are competing energy processes in the body. This temporary appetite suppression can be helpful for weight management, but it’s important to ensure that you’re still meeting your nutritional needs, especially if you're more active or walking more on holiday.

Tip: Focus on smaller, nutrient-dense meals throughout the day. Cold dishes like salads with lean protein, chilled soups (gazpacho), and hydrating fruits (like watermelon or cucumber) are perfect for hot days and provide both energy and hydration.

3. Travelling in Europe? Climate, Cuisine, and Routine Matter

If you’re heading to southern Europe, like Spain, Italy, Greece, you’re likely to experience hotter days, longer daylight hours, and late-night meals. These environmental and cultural shifts can disrupt your normal appetite regulation.

Heat can suppress hunger during the day, but late evening temperatures and social eating patterns (like longer dinners) may increase evening calorie intake. Additionally, access to alcohol and rich foods while on holiday can mask satiety signals and lead to passive overconsumption.

Tip: Balance indulgence with intentional habits. Start your day with a hydrating breakfast (think Greek yoghurt with fruit), carry a reusable water bottle, and use meal times to slow down and check in with your hunger, especially after spending time in the sun.

4. Hydration Supports Metabolism and Weight Regulation

Beyond controlling appetite, hydration plays a critical role in metabolic efficiency and fat oxidation. Even mild dehydration (as little as 1–2%) can impair exercise performance and cognitive function, reducing motivation to move or prepare healthy meals.

A systematic review in Frontiers in Nutrition (2021) found that optimal water intake is associated with better weight regulation, especially when water replaces high-calorie drinks. In summer, when you're naturally sweating more, especially during outdoor walks, hikes, or swimming. It's crucial to proactively hydrate, not just reactively.

Tip: Aim for 2–2.5 litres of water daily in warmer months, increasing if you're active or spending time in direct sun. Sparkling water, herbal teas, or adding citrus and herbs can help improve flavour and keep things varied without relying on sugary drinks.

Final Thoughts

Staying hydrated in summer isn’t just about avoiding heatstroke. It’s a subtle but powerful tool in managing hunger, supporting metabolism, and maintaining healthy routines.

Whether you’re enjoying a staycation in the UK or travelling across Europe, understanding the relationship between hydration, heat and hunger can help you feel more in control of your weight management goals; without falling into restriction or reactive habits.

Sources:

Maughan RJ, Shirreffs SM, Watson P. Exercise, heat, hydration and the brain. Journal of the American College of Nutrition, 2007.
Mattes RD, Campbell WW. Effects of food form and timing of ingestion on appetite and energy intake in lean young adults and in older adults. Journal of Nutrition, 2009.
Kavouras SA. Hydration, dehydration, and exercise performance. Nutrition Reviews, 2002.
Adams JD, et al. The effects of hydration on metabolic rate and fat oxidation. Frontiers in Nutrition, 2021.
Leiper JB. Fate of ingested fluids: factors affecting gastric emptying and intestinal absorption of beverages in humans. Nutrition Reviews, 2015.