I have to ask, because my non-native speaking ass thought you were wrong for a moment. Context aside, it "affects" the body and therefore "has an effect on" the body, right?
Plot twist: they are both verbs and nouns, but the noun affect only gets used in psychology
From wiktionary:
“New governing coalitions have effected major changes” indicates that major changes were made as a result of new governing coalitions.
“New governing coalitions have affected major changes” indicates that before new governing coalitions, major changes were in place, and that the new governing coalitions had some influence over those existing changes.