Why do we feel less hungry when it's hot?

In summer or during a heatwave, many people notice that they feel less like eating. Hearty meals become less appealing, while fresh foods, fruits, or salads seem more appetizing.

This decrease in appetite is a well-known phenomenon. It is a normal adaptation of the body to high temperatures.

However, even when hunger is less felt, nutritional needs do not disappear, especially for athletes whose energy expenditure remains significant.

Why do we feel less hungry when it's hot? What mechanisms explain this phenomenon? And how can we continue to meet our needs despite a reduced appetite?

Heat alters the body's priorities

The human body constantly strives to maintain a stable internal temperature, close to 37 °C.

When the outside temperature rises, it mobilizes various mechanisms to dissipate excess heat:

• increased sweating;
• dilation of blood vessels in the skin;
• increased water loss.

In this context, thermoregulation becomes a priority for the body.

Temporarily reducing appetite is one of the adaptations that helps limit the additional heat production linked to digestion.

Digestion produces heat

Eating requires energy.

Digestion, nutrient absorption, and metabolism are accompanied by heat production known as dietary thermogenesis.

The more substantial a meal, the greater this heat production.

When temperatures are already high, the body naturally tends to limit this additional expenditure by reducing hunger signals.

This is one of the reasons why very rich or hot dishes often seem less appealing in the summer.

Appetite hormones are influenced

The feeling of hunger depends on many hormones, including ghrelin and leptin.

High temperatures seem to alter their function and the signals sent to the brain regarding food needs.

Although the exact mechanisms are still being studied, several studies show that high temperatures are associated with a spontaneous decrease in energy intake in many people.

In other words, the decrease in appetite is not just psychological: it is also based on physiological adaptations.

Why do we prefer fresh foods?

When the heat sets in, food cravings naturally evolve.

Water-rich foods often become more attractive:

• watermelon;
• melon;
• strawberries;
• cucumber;
• tomatoes;
• mixed salads.

These foods provide a feeling of freshness while contributing to hydration.

They are also generally easier to digest than meals very rich in fat.

Nutritional needs do not necessarily decrease

Feeling less hungry does not mean that nutritional needs disappear.

For active individuals and athletes, energy, protein, carbohydrate, and micronutrient needs often remain significant despite the heat.

Insufficient intake for several days can lead to:

• a drop in energy;
• more difficult recovery;
• decreased performance;
• muscle mass loss in case of prolonged deficit.

It is therefore important to adapt your diet without neglecting your needs.

Risks for athletes

For athletes, decreased appetite can be exacerbated after training performed in hot conditions.

However, it is precisely after exercise that the body needs:

• carbohydrates to replenish glycogen stores;
• proteins to support muscle recovery;
• water and electrolytes to compensate for sweat losses.

When meals become difficult to finish, it may be beneficial to opt for smaller but more frequent portions throughout the day.

How to continue eating well despite the heat?

A few simple strategies can help maintain sufficient intake:

• fractionate meals;
• prioritize fresh foods;
• consume easily digestible proteins such as dairy products, eggs, or fish;
• add fruits to snacks;
• prepare complete salads containing starches and a protein source.

Smoothies or yogurts enriched with fruits can also be interesting options when appetite is limited.

Should you eat less when it's hot?

There's no need to force yourself to finish a very heavy meal if you're not hungry.

However, it is better to adapt the meal format rather than skip meals entirely.

Lighter but balanced meals generally allow for better coverage of nutritional needs while remaining compatible with a temporary decrease in appetite.

The importance of hydration

The sensations of thirst and hunger can sometimes be confused.

Furthermore, dehydration can accentuate fatigue and further decrease the desire to eat.

It is therefore essential to:

• drink regularly throughout the day;
• increase intake in case of significant sweating;
• consume water-rich foods;
• use electrolyte-containing drinks during prolonged exertion or in hot weather if necessary.

Key takeaways

Feeling less hungry when it's hot is a normal response from the body. By temporarily reducing appetite, the body limits heat production linked to digestion and focuses its efforts on maintaining its internal temperature.

However, this decrease in appetite does not mean that nutritional needs disappear, especially for athletes. Adapting meal formats, prioritizing fresh foods, maintaining sufficient protein intake, and ensuring good hydration help meet the body's needs throughout the summer.