this.peso

Ao setar os valores do imc no objeto pacient, tentei pegar os valores de peso e alura com o "this".

var btnAddPacient = document.querySelector("#adicionar-paciente");

btnAddPacient.addEventListener("click", function(event){

    event.preventDefault();

    var form = document.querySelector("#form-adiciona");

    var pacient = getPacientForm(form);

    var pacientTr = createTrElement(pacient);

    var table = document.querySelector("#tabela-pacientes");
    table.appendChild(pacientTr);
});

function getPacientForm(form){

    var pacient = {
        name : form.nome.value,
        weight : form.peso.value,
        height : form.altura.value,
        fat : form.gordura.value,
        imc : calculaImc(this.weight, this.height)
    }
    return pacient;
}

function createTrElement(pacient){
    var pacientTr = document.createElement("tr");

    pacientTr.appendChild(createTdElement(pacient.name));
    pacientTr.appendChild(createTdElement(pacient.weight));
    pacientTr.appendChild(createTdElement(pacient.height));
    pacientTr.appendChild(createTdElement(pacient.fat));
    pacientTr.appendChild(createTdElement(pacient.imc));

    return pacientTr;
}

function createTdElement(data){
    var td = document.createElement("td");
    td.textContent = data;
    return td;
}

Porém, o valor que aparece no formulário após os dados serem preenchidos é NaN. Por que não deu certo?