Charlie Myer won't leave the house without wearing his chest binder, though he knows it may be endangering his health.

The 22-year-old Wellington student said he has been using the chest binder for the past two years, just before he came out as a transgender man.

"During that time, I've had gender dysphoria with my chest because I just want it to be flat," he said.

SUPPLIED Charlie Myer says he has been using the chest binder for the past two years, just before he came out as a transgender man.

A chest binder is a purpose-built medical undergarment a little like a sports bra but it's designed to compress the breasts into a masculine shape.

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It's restrictive - it sits tightly enough around the ribs to stop normal breathing. And if used long-term, it can also cause back pain and other health problems.

"Binders are a temporary solution for people who are waiting for top surgery or just a sometimes or occasional garment that you wear because if you wear it too frequently, it can cause a lot of damage to your body," Myer said.

Cameron Burnell Gender Minorities Aotearoa national co-ordinator Ahi Wi-Hongi said there was currently a waiting list of about 100 people for the organisation's free national chest binding programme to support people who needed a binder but couldn't afford it.

"I have a couple of friends that have been binding for five years that have suffered back pain - it can end up being chronic because of it."

But without it, Myer said he feels very self-conscious in public.

"I feel like all eyes are on me and that they're all reading me as a person I'm not, or the person that I understand myself to be," he said.

"Even if I'm by myself and I'm out of the house, I just don't feel comfortable. Sometimes it's affected by other people's perception and sometimes it's just like a miscommunication almost, between how I understand myself to be and how I'm presenting."

SUPPLIED Gender Minorities Aotearoa offers a free national chest binding programme to support people in Aotearoa who need a chest binder but can't afford to buy one.

The binder isn't easy to wear though. Myer said it "restricts his life", preventing him from swimming, going to the gym or enjoying a long walk with friends.

"Often when I go out with friends, we have to stop for a while because I just need to catch my breath.

"It can be really difficult in summer time as well because it's obviously another layer of clothing on you and so it isn't easy. You sweat a lot, which is really uncomfortable and sometimes it just means I just don't leave the house because if it's too hot to wear my binder, then I just won't go outside.

"It just ends up being an obstacle in my life."

Myer doesn't plan to wear the chest binder for much longer. This year, he will undergo top surgery, a double mastectomy to remove breast tissue, then reshape into a masculine chest.

Because it's not offered in the public health system in Wellington, he has opted to have the procedure done privately, which costs $20,000.

Despite being a student - he's just graduated with a creative media production degree, he's already saved $10,000 toward the cost of the surgery. His family has offered to help with some of the cost and he's launched a givealittle fundraising campaign to raise the final $2000.

"The response has been so overwhelming, it is really awesome. I'm really lucky to have a really accepting family and friends that support me. There's just been such an intense amount of support shown to me, which is really humbling."

Physiotherapist Sophie Aitchison, whose Willis St Physiotherapy centre in Wellington started a transgender and non-binary physiotherapy clinic last year, said the biggest risk was chest binding with materials that weren't stretchy or mobile, such as duct tape.

"You basically restrict the amount that the ribs can move and what that can cause is stress fractures over time."

Aitchison said chest binding undergarments were a better option, however, they still caused painful compression to the rib cage and soft tissues around it. It could also cause breathing difficulties, fainting or abnormal breathing patterns.

"It can be risky but it can also be something that can be a lot safer if done with the right education and advice," she said.

Gender Minorities Aotearoa national co-ordinator Ahi Wi-Hongi said there was currently a waiting list of about 100 people for the organisation's free national chest binding programme to support people who needed a binder but couldn't afford it.

The garments can cost around $80 plus shipping from the US but were the safest form of chest binding, she said.

The programme was developed with physiotherapists to include safety information, including how to wear the binder, breathing techniques, the importance of stretching back and arm muscles and not wearing it for more than eight hours a day.