This is the result I get when I do that. The code just simply does not show up.

This is my updated code after doing what you told me to (not sure if correctly):

        #include <iostream>
        #include <string>
        #include <iomanip>
        #include <fstream>

        using namespace std;


    int main()
    {

        // Housekeeping

        string name, result;
        char c = 'y';
        int counter = 0;
        double BMI, height, weight, WEIGHTINLBS, HEIGHTININCHES, total_BMI = 0.0;
        const double LB2KG = 0.45359237, INCH2METRE = 0.0254;
        cout << fixed << setprecision(1);

        ofstream fout("bmi.dat");
        fout << fixed << setprecision(1);
        if (!fout.is_open())
        {
            cout << "error opening file ";
            return 0;
        }

        // Input

        fout << setw(10) << "   Body Mass Index Report " << endl;
        fout << left << setw(20) << "Name" << setw(20) << "Weight" << setw(20) << "Height" << setw(20) << "BMI" << setw(20) << "Result" << endl << endl;

        while (c == 'y' || c == 'Y')
        {
            system("cls");
            cout << "Enter your name: ";
            getline(cin, name);
            cout << "Enter weight(lbs): ";
            cin >> weight;
            cout << "Enter height(inches): ";
            cin >> height;

            // Processing

            WEIGHTINLBS = weight * LB2KG;
            HEIGHTININCHES = height * INCH2METRE;
            BMI = WEIGHTINLBS / (HEIGHTININCHES * HEIGHTININCHES);

            if (BMI < 18.5)
            {
                result = "Under weight";
            }
            else if (BMI > 24.9)
            {
                result = "Over weight";
            }
            else
            {
                result = "Normal weight";
            }

            // Output

            fout << left << setw(20) << name << left << setw(20) << weight << setw(20) << height << setw(20) << BMI << setw(20) << result << endl << endl;

            cout << "Do you want add more entry? (Y or N): ";
            cin >> c;

            total_BMI = total_BMI + BMI; counter++;
        }

        cout << "The total BMI is " << total_BMI << endl; cout << "The number of people used is " << counter << endl;

        double average_BMI = total_BMI / counter;

        cout << "the average BMI is " << average_BMI;

        system("cls");
        system("type bmi.dat");
        system("pause");
    }