The gust is assumed to produce a
change in angle of attack, a positive gust increasing alpha. If you are heavy
and flying level at 4deg alpha and the gust adds one deg, which is a 25%
increase in lift, or 1.25g. If you had been light and holding 3 deg alpha for
level flight the gust would give you a 33% increase in lift, 1.33g. If you are
measuring gust effect by g, as you do, then light is bad, heavy is good.
Imagine a really heavy aircraft
flying with the wings flapping away but the fuselage just steaming along
This brings in another issue.
For the heavy aircraft, the stress at
the wing attachments will be higher and it will use up fatigue life faster. So
for long fatigue life fly smooth and fly light…