Fasting and the female fighter

Almost every study of fasting and athletic performance was carried out in men, and almost every article written from those studies quietly assumes the reader is one. The variables that move first in a female athlete are not the ones being measured.

Whether to fast, and whether an exemption applies, is a matter for the athlete and for whoever advises her on her faith. It is not a question for a nutritionist.

What follows assumes the decision is made and is about protecting training while it is kept.

Energy availability is the variable, not body mass

Body mass is a poor signal during a fasting period, because it moves with fluid and tells you nothing about whether the athlete is fuelled. The measure that answers the question is energy availability: what she eats minus what training costs, per kilogram of fat-free mass.

Below 30 kcal/kg of fat-free mass a day is the threshold associated with risk, and 45 is where nothing is being taken out of her. A month of two eating windows, or 7 weeks without meat, dairy and eggs, can put an athlete under that line without a single deliberate restriction.

The full picture is in REDs, and the figure itself takes a minute on the energy availability calculator.

The cycle as information

A cycle that becomes irregular, lighter, or stops during or after a fasting month is the most accessible signal that intake is not covering the work, and waiting it out wastes the warning.

Track it through the period rather than remembering it afterwards. If something changes, look at intake first and speak to a doctor if it persists, rather than training harder around it. How the cycle interacts with training and weight more generally is in the menstrual cycle, and what hormonal contraception does to that signal is in contraception, because it can hide exactly the change you are watching for.

Iron, in a month that removes it

Female combat athletes frequently start the year with iron on the low side, and both major fasting periods make it harder rather than easier: one compresses the eating into two windows, the other removes red meat for 7 weeks.

Plant iron is absorbed less readily than iron from meat, and absorption improves markedly in the presence of vitamin C at the same meal.

That is a free adjustment: something acidic and fresh alongside the legumes rather than after them.

What not to do is start supplementing iron on a hunch. It is measured with a blood test, treated on the basis of that test, and the detail is in iron.

Bone, which nobody feels

The Lenten fast removes dairy for 7 weeks and the Ramadan pattern compresses when calcium arrives.

Neither will be felt during the period, and that is precisely the problem: bone is the variable that reports late.

For an athlete who keeps a fast every year across a career, this is a repeated exposure rather than a single month.

That accumulates, particularly alongside weight cutting, and the case is set out in bone health.

What to actually do

• Run the energy availability figure in the first week, not the last. Knowing you are under the line on day five is useful. Knowing in week four is history.
• Protein at every opportunity the fast allows, aiming at the upper end of 1.6 to 2.0 g/kg rather than the lower.
• Track the cycle through the period and for the month afterwards.
• Do not run a weight cut inside a fasting period unless the calendar leaves no choice. If it does, plan them as one thing.
• Vitamin C alongside plant iron, at the same meal.

The month is not the problem

Nothing here argues that a female athlete should not fast. Plenty do it every year and train well through it, and the ones who do have almost always planned it rather than endured it.

What goes wrong is the assumption that a body which is smaller, often already low on iron, and running an additional hormonal system will respond to a restricted month exactly like the men in the studies.

It will not, and the difference shows up first in the places nobody was watching.