Carola Long: Forget science: as every fashionista knows, black is best

What impact will the revelation that horizontal stripes are flattering have on the world of truly high fashion?

Absolutely none. The most avant-garde designers don't let pedestrian details such as whether certain patterns add pounds interfere with their creative visions.

And besides, the women who wear these straight-off-the-catwalk pieces are generally so thin that they could wear five coats on top of each other and still look slender.

Away from the catwalks, the insight is also likely to be treated with a degree of scepticism, because, although these kind of fashion rules are a bit passé and real style can't be achieved through a set of mathematical formulae alone, experience shows that some clothes are more slimming than others.

While a Breton-style top with fine stripes won't make anyone look larger, thick horizontal bands can make the wearer resemble a zebra crossing. Similarly, small, delicate patterns are more flattering than big patterns.

Black is genuinely slimming, which is why it's the fashion industry's favourite colour, and accordingly, dark denim jeans are a better option than a pale pair.

Double-breasted jackets have a reputation for adding bulk, and single-breasted styles actually do create a narrower silhouette.

In terms of shoes, ankle straps truncate the leg, as do ankle boots with skirts, but they are a big trend at the moment, nevertheless.

Lace patterned tights are also a key look this season, but the busy design is far less flattering than a pair of black or dark grey opaques.

Carola Long is Deputy Fashion Editor at The Independent