Australia's jockeys can be a cranky bunch, and research shows the reason is their constant battle with the scales.
A study has found 83 percent of jockeys feel their strict diets and the process of "wasting" - which can involve saunas, appetite suppressing drugs or self-induced vomiting - makes them moody.
More than half also said it made them feel depressed (63 per cent), or angry (52 percent), while many also reported feeling fatigued (79 percent), dizzy (62 percent) or nauseous (45 per cent).
Dr Vivienne Sullivan says the demands of the sport, all to meet the exacting weight requirements of race day, also had a big impact on jockeys' social lives.
"Many jockeys are unable to celebrate their successes and often do not attend, or eat steamed veggies when the rest of their family is having Christmas dinner," Dr Sullivan said.
"The use of unhealthy weight control to achieve minimum riding weights is a major concern".
When it came to the social impact, 76 percent of jockeys reported having strained relationships and a daily preoccupation with their weight which dominated other aspects of their lives.
Dr Sullivan studied jockeys for her recently completed PhD in Psychology at Victoria University.
She surveyed or conducted personal interviews with about a quarter of Victoria's 189 flat-race jockeys, along with their families and other industry professionals.
Dr Sullivan says the fact that Australia had no racing off-season ensured that jockeys had little reprieve from the rigours of wasting.
Many jockeys also felt they could not reject a ride without affecting their relationship with the horse owner or trainer involved.
Dr Sullivan says Australia's racing industry should increase the minimum riding weights for jockeys and also introduce a system of guaranteed time off.
Without this, it was "entirely possible for Australian jockeys to ride all year without taking a break", she said.
In Victoria, minimum riding weights were recently increased by one kilogram to 51 kilograms for Group 1 city races (except the Caulfield and Melbourne Cups, which is 50 kg) and to 52 kg for Group 2 or country races.
