kcal = kilocalorie = 1000 calories
EVA = Extra Vehicular Activity = Space walk
How Many Calories Do Astronauts Need On A Regular Day In Space?
Calorie intake on the ISS ranges from about 2500 to 3200 kcal/day. This is considerably higher that what is normally recommended for an adult man (2,500 kcal) and women (2,000 kcal), but this reflects the fact that astronauts use more energy than most people here on Earth because they exercise twice per day, most days of week.
In addition, astronauts’ bones become thinner and weaker in space, and we know that – as well as exercise – making sure you eat enough (i.e. the amount of energy you use is not greater than the amount you take in) is an important factor in minimising this bone loss.
How Many MORE Calories Do Astronauts Need If They Are Performing an EVA?
Energy use during an EVA is approximately 250 kcal/hour – an extra 175 kcal/h above resting levels. However, EVAs also include several short, 5–10 min periods of high intensity effort, when energy expenditure can be as much as 400 kcal/h. EVA’s often last between 6-8 hours.
So the total number of EXTRA calories required for a 6 hour EVA would be approximately 1100 kcal.