What effect does weed have on the body?

Depends whether you're using a Sativa or an Indica strain.

Sativas tend to be quite energetic, and give a feeling of confidence and in some users even pain relief. Sativas have a higher THC content that Indicas, but a lower CBD content. Visual trips have also been reported.

Indicas tend to relax you and give you a heavy feeling, quite the opposite of Sativas. Indicas also give stress and pain relief. Indicas have a high CBD content, which means the effects last slightly longer than the Sativas.