Trousers with a loose-cut and fit are useful in countries that have a warm and potentially sweaty climate. They are also great at defining a particular style for the wearer – either a super-casual look or the slightly overlarge zoot-suit style.
Loose cut trousers have extra width both in the waist – where they are likely to be pleated to ensure that the waistband can fit normally – and down the legs too (so that the base of the leg is wider than normal).
For men who are heavier, a pair of loose cut trousers that provide a good line without exaggerating the additional weight. For any body type, though, the relaxed fit makes for a great casual look.