Calories and water in the heat
Estimate the calories you need each day and a sensible range of water for the UAE heat, with an option for fasting in Ramadan. For adults. Not medical advice.
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Heat illness: know the signs
Heat exhaustion: heavy sweating, cold, pale and clammy skin, a fast weak pulse, cramps, nausea, tiredness, dizziness or a headache. Move to a cool place, loosen clothes, sip water and rest.
Heatstroke is an emergency: a very high body temperature, hot red skin (dry or damp), a fast strong pulse, confusion, slurred speech or passing out. Call 998 (ambulance) or 999 now, and cool the person while you wait. Don't give drinks to someone who is confused or not fully awake.
Heat exhaustion or heatstroke? Learn the differenceIftar to suhoor: are you drinking enough?BMI calculator
How the numbers are worked out
The Mifflin-St Jeor equation estimates what you burn at rest (BMR). An activity factor from 1.2 to 1.9 scales it up to what keeps your weight steady. Real needs can differ by a few hundred calories a day.
The loss and gain ranges are 250 to 500 calories a day away from your maintenance, about 0.25 to 0.5 kg a week. The page never suggests going below 1,200 a day for women or 1,500 for men: lower than that needs a doctor's supervision.
European and US expert bodies set an adequate total water intake of 2.0 to 2.7 litres a day for women and 2.5 to 3.7 litres for men, from drinks and food, for people in mild weather. About 80% usually comes from drinks, so the drinks range starts at about 1.6 to 2.2 litres for women and 2.0 to 3.0 litres for men.
Exercise and hours outdoors in the heat add to that: a rough 0.3 to 0.5 litres for each hour outside in the hot months (less in cooler months). Because outdoor work is also activity, the page counts the bigger of the two in full and the smaller by half. People working hard in constant heat can need 6 litres a day or more. But don't drink more than about 1.4 litres in one hour: too much water too fast is also dangerous.
Check the colour
The easiest check is your urine: pale straw yellow means you are drinking enough. Darker yellow means drink more. Very dark or brown urine, or hardly any, can be a sign of dehydration: drink and, if it doesn't improve, see a doctor.
Not medical advice. These are general estimates for healthy adults. Ask a doctor first if you are pregnant or breastfeeding, under 18, over 65, or have a kidney or heart condition (some people are told to limit fluids), diabetes, or take medicine such as diuretics. Children's needs are different: ask their doctor.
Sources: Mifflin MD, St Jeor ST et al., "A new predictive equation for resting energy expenditure in healthy individuals", American Journal of Clinical Nutrition, 1990;51:241–247 (activity factors 1.2 to 1.9 are the multipliers commonly used with it); US National Heart, Lung, and Blood Institute, Clinical Guidelines on Overweight and Obesity in Adults, 1998 (about 500 kcal a day for about 0.5 kg a week); Harvard Health Publishing, "Calorie counting made easy" (not below 1,200 kcal a day for women or 1,500 for men except under a health professional's supervision). Water: European Food Safety Authority, Scientific Opinion on Dietary Reference Values for water, 2010 (adequate total intake 2.0 L women, 2.5 L men; +300 ml in pregnancy, +700 ml when breastfeeding; children 4–8 years 1.6 L, 9–13 years 1.9 L girls and 2.1 L boys; 14 and over as adults); US National Academies, Dietary Reference Intakes for water, 2004 (about 2.7 L women and 3.7 L men in total, about 80% from drinks; very active people in constant heat may need 6 L or more); US CDC and NIOSH, "Heat Stress: Hydration", 2017 (one cup every 15–20 minutes when working in heat, no more than 48 oz, about 1.4 L, an hour). The extra per hour outdoors is this page's rough estimate, not an official figure. UAE Ministry of Health and Prevention (MOHAP) heat safety advice, July 2024, as reported by Gulf News (drink water regularly, avoid the midday heat, go out early or late, light loose clothes, water-rich fruit). Heat illness signs: CDC and NHS. Ramadan split: Daman and Dubai Health Authority Ramadan advice to spread drinks across the non-fasting hours; the split shown is an example. Not medical advice.