She is not a gymnast, so you assume she is fine

A coach who has read anything about young female athletes has read about gymnasts, distance runners and dancers.

That literature describes chronic energy restriction producing delayed menarche, absent periods and thin bones, and it has trained a generation of coaches to look for a specific silhouette.

A 16-year-old boxer does not look like that. She trains hard, eats normally most of the time, and cuts weight for 4 days before a competition.

Which is why the risk in her case is frequently missed, and why it arrives by a route the standard picture does not cover.

The arithmetic that separates her from an adult

An adult athlete needs energy for two things: staying alive and training.

An adolescent needs energy for three. The cost of growth and pubertal maturation is superimposed on the training load rather than replacing part of it.

That addition is large enough that a 16-year-old and a 26-year-old on the same programme, eating the same food, are in different situations, and the younger one is the one who runs short.

And she runs short at the point in her life when the consequences last longest.

What low energy availability does at this age

Sustained low energy availability disrupts reproductive hormone signalling. In an adolescent that shows as delayed menarche, irregular cycles, or periods that stop after starting.

Reduced oestrogen means reduced bone accrual, and adolescence is when bone is being built toward a lifetime ceiling.

Weight manipulation during the years of peak bone accrual can delay puberty and compromise the attainment of peak bone mass.

That sentence deserves reading twice by anybody running a junior girls' programme, because both halves are permanent in a way almost nothing else in sport is.

And it is not only bones and periods

Energy deficiency is systemic, and the parts a coach actually sees are usually attributed to something else.

• Thyroid hormone falls, T3 in particular, and resting metabolic rate drops with it. The athlete becomes harder to lean out, which is frequently answered with more restriction.
• Immune function is suppressed. Frequent illness and injuries that keep recurring are part of the picture rather than bad luck.
• Iron status falls fast in adolescent girls under dietary restriction. Ferritin drops, then haemoglobin, and the athlete loses work capacity.

That last one is worth dwelling on, because it produces a specific misreading. An iron-deficient girl looks out of shape. She fades in rounds, her recovery between sessions worsens, and a coach concludes she has not been training hard enough.

The response to that conclusion is usually more work and less food, which is precisely the wrong direction. The iron material covers the testing.

And the sentence that matters most

Female athletes commonly experience amenorrhoea at some point in training, and it is frequently treated inside gyms as a normal consequence of being an athlete.

One further complication is specific to this sport. Hormonal contraception can produce a withdrawal bleed that looks like a normal cycle while underlying function is suppressed, which means the absence of an obvious problem is not evidence there is not one. That belongs with a clinician rather than in this article.

The different door

This part applies to weight-category sport specifically and rarely gets said.

Female athletes in weight-category sports may appear less likely to develop menstrual disorders and low bone density than gymnasts or distance runners, because they are not in chronic restriction. Much of the year they eat adequately.

But the dietary restriction associated with rapid weight loss can itself induce disordered eating in adolescent female athletes.

Which produces a different route to the same destination.

The gymnast arrives through years of continuous restriction. The young fighter arrives through repeated cycles of severe short-term restriction, each one normalised by the sport, each one teaching that food is something to be controlled and that a particular feeling of emptiness is professional.

The development of disordered eating and eating disorder behaviours peaks during adolescence. Running a girl through several weight cuts in that window is not the same intervention as running an adult through them.

And the finding that complicates the alarm

None of this is an argument against girls competing, and the long-term data point the other way.

In a study of over 1,000 women aged 47 to 55, those who had participated in competitive sport in adolescence had higher midlife lean mass, higher bone mineral density and better physical performance than those who had done regular activity or none.

Competitive sport in adolescence was protective across decades.

The same study found that women whose menarche occurred at 14 or later had lower midlife bone density than those whose menarche was at 12 or earlier.

Read together, the message is precise rather than alarming. Sport is good for her. Energy deficiency that delays her development is the specific harm, and it is separable from the sport.

A coach's job is to make sure the competing does not cost her the thing the competing would otherwise have given her, which is a different job from keeping her out of it.

Both the frequency and the size matter

It is tempting to say that the number of cuts matters more than the depth of any one. That is wrong, and stating it that way gives permission for the thing that does the most damage.

Both are constraints, and neither buys permission for the other. A club running one deep cut a year has not solved the problem, and a club running five shallow ones has not either.

The correct response to a girl who is growing is the same as for a boy: move up. The correct response to a calendar requiring five cuts a year at 16 is to enter fewer of them.

What a coach should actually do

Know whether she has started menstruating and whether it is regular. This is uncomfortable and it is basic health monitoring rather than an intrusion.

It does not require the coach to be the person asking. In most programmes the right arrangement is that a female staff member, a team doctor or a designated welfare officer holds this information, and the coach knows only whether there is a flag.

A club with no route for this has decided not to know something directly relevant to the athlete's long-term health.

Watch for the pattern rather than the physique. She may not look underweight. The signals described under gym culture are more useful: inability to take a rest day, withdrawal from team meals, secrecy around food, training added that nobody prescribed.

Refer rather than manage. Menstrual dysfunction, suspected disordered eating and questions about bone health all belong with a clinician. A coach's part is noticing, raising it privately, and making the referral happen.

The conversation, and who should have it

Most male coaches are uncomfortable with this and the discomfort produces silence, which is the worst available outcome.

Two things resolve most of it.

Have a woman on the staff, or accessible to it, whose role includes this. A club that has never arranged this in a sport with female athletes has an obvious gap.

And separate the two conversations. Health monitoring is routine, applies to everybody, and is held by whoever holds it. A specific concern about a specific athlete is private, raised gently, and routed onward.

What to tell a parent

Parents of adolescent girls in this sport ask about weight cutting and they are right to.

• Competing is good for her, and the long-term data support that.
• Energy deficiency during her growth years is the specific risk, and it is not an inevitable part of the sport.
• The club's position is that she moves up rather than cuts hard while growing, that periods are monitored as routine health information, and that anything concerning goes to a doctor rather than being handled internally.

A parent who hears that has been told something specific rather than reassured, and a club that can say it has thought about the problem before being asked.

The thing to hold on to

The picture coaches are trained to watch for is a thin girl who has not eaten properly in 2 years.

The girl in front of you eats reasonably, looks strong, and has done four hard cuts since January.

She is in a different pattern and she is not necessarily in less danger, and the reason this article exists is that the standard warning does not describe her.