Scientists have found that women order smaller and less calorific meals if eating with a man, than they do if dining with female friends.

Tests by psychologists showed that women eating with a single male companion were more likely to order a salad than a steak, but that this changed when eating with another woman.

When ordering in mixed-gender groups womens food choices were at the lower end of the caloric scale, but the more men in the group the fewer the calories. When in all female groups women pigged out.

Experts at McMaster University think the choice could be subconsciously controlled by a desire to signal attractiveness, which apparently smaller portions do.

However researchers did not look at why, even though a woman orders a salad when you go out together, she invariably pinches half of your chips ... like calories from your plate don't count.