Fuselage contributing to lift
The wing lift is associated with drag, called lift-dependent drag or 'induced' drag. It is a function of the wing aspect ratio and the spanwise lift distribution. To minimize induced drag you want to have a high aspect ratio and ideally an elliptical spanwise lift distribution. The drop-off of lift near the tip causes the tip trailing vortices.
If the lift dropped to zero at the wing roots you would effectively have two wings with half the aspect ratio and twice the induced drag as the complete wing, and 'tip' vortices at the tips and wing roots.
That doesn't happen. The spanwise lift distribution is continuous across the fuselage except perhaps a slight dip. In other words, the fuselage contributes to the overall lift.
Last edited by Gysbreght; 14th Nov 2018 at 08:57.
Reason: correction of typographical error