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French Agency for Food, Environmental and Occupational Health & Safety

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Updated on 24/08/2016

Hot weather: modify your eating habits

Recommendations by ANSES in the framework of the national heatwave plan

Keywords : Heatwave

During a heatwave, the risk of dehydration is higher. Certain recommendations which are valid throughout the year take on increased importance during very hot weather, especially for certain sensitive populations.When the weather is hot the body self-regulates to maintain a stable temperature, which causes higher amounts of water to be lost than usual. During a heatwave, the risk of dehydration is even greater.

When the weather is hot the body self-regulates to maintain a stable temperature, which causes higher amounts of water to be lost than usual. During a heatwave, the risk of dehydration is even greater.

To counteract the risk of dehydration:

  • Drink fluids regularly, before you actually feel thirsty.
  • Avoid alcoholic beverages, which cause dehydration, as well as beverages high in sugar or caffeine, which have a diuretic effect.
  • Eat water-rich foods (fruits, vegetables, dairy, etc.) that add to your fluid intake.

Manual labourers, especially those who work out-of-doors, and people who perform sports activities in the open are also at high risk for dehydration when the weather is hot. It is therefore essential that these individuals consume sufficient amounts of water to make up for water losses, and that they protect themselves from the heat as much as possible.


Special recommendations for sensitive populations

In hot weather, it is especially important to attend to the needs of people over 65 years of age, as well as infants and young children under 3 years of age, since they are particularly sensitive to the risks of dehydration and heat stroke when the ambient temperature is high.

Children's bodies are 90% water, adults 70% and elderly people 60%. Also, the elderly are less effective at fighting the heat through perspiration. In addition to general recommendations for reducing the risks of dehydration, appropriate food consumption advice targeting these populations aims to ensure they receive a balanced water intake.


The elderly

Renal function is also reduced in older people, causing difficulty in eliminating water if intake is excessive. It is therefore important that elderly individuals drink sufficient amounts of water while avoiding excess.

  • It is recommended, for example, that the elderly drink the equivalent of at least 8 glasses of water a day (800 mL), the ideal amount being 13-14 glasses a day.
  • In periods of very hot weather, chlorination of tap water may be increased for microbiological safety reasons. The chlorine taste will disappear if water is left to stand for a few minutes after being drawn from the tap.
  • Drink moderately mineralised water (low osmotic strength), for example mixing sparkling waters, which are highly mineralised, with tap water.
  • Drink fluids regularly in order to anticipate the sensation of thirst.


If you don't like the taste of plain water, you can vary your fluid intake by drinking:

  • iced tea or coffee
  • squash diluted in water or taken in the form of ice cubes
  • gazpachos or cold soups
  • fruit purees
  • sorbets rather than ice-cream, as they contain more water
  • fruit juices
  • water-rich fruits and vegetables such as watermelon, cantaloupe melon, strawberries, peaches, tomatoes, courgettes and cucumbers
  • yoghurt (1 yoghurt hydrates as well as a glass of water), cottage cheese


Children under three

  • Have your child drink frequently, at least once per hour during the day - chilled water, from a baby bottle or glass according to age - without waiting until they show signs of thirst.
  • At night, give chilled water to drink whenever the child wakes.
  • Children with a diversified diet should be given fresh fruit (watermelon, cantaloupe melon, strawberries, peaches) or fruit puree, green vegetables (courgette, cucumber) and dairy (yoghurt, cottage cheese) at mealtime.