TOKYO, JAPAN and ESSEX, ENGLAND — The urge to merge sexually often is described as an “appetite.” As it turns out, the food analogy may be particularly apt. Two studies have found links between eating behaviors, body mass and intercourse.A study backed by Japan’s health ministry discovered a possible link between breakfast and the age at which subjects lost their virginity. Among a sample of 3,000 young people, those who ate breakfast hung on to their chastity an average of two years longer (19.4 years) than those who skipped the morning meal (17.5 years).

Japanese researchers concluded an unstable or unhappy home life contributed to rebellious behavior, including early sexual experimentation, among teens.

“Those unhappy with their parents — such as for not preparing breakfast — may tend to find a way to release their frustration by having sex,” Kunio Kitamura, head of the Japan Family Planning Association and lead researcher on the project, told AFP. “If children don’t feel comfortable in their family environment, they tend to go out.”

That may contribute to a vicious cycle of sorts, Kitamura added, because young people who return home late because they’ve been out having sex may skip breakfast in order to sleep in.

The study also found that 40-percent of Japanese adults hadn’t had sex in more than a month. Most blamed the lack of intimacy on job-related fatigue, although some said they simply found the act to be “too much trouble.”

That could be part of the reason for the country’s low birth rate among married couples, researchers concluded.

In Western societies, however, sexual frequency and appetite seem to be related in another way: Size matters, and not the size you’re thinking.

According to a LighterLife.com survey, British women who wear a size 8 have the most sex: 60-percent of size 8 ladies reported having intercourse within the past week. About 50-percent of size 12 women reported bedding someone at least as recently.

As body mass increases, however, intercourse frequency decreases: Only 33-percent of size 26 women reported having sex weekly.

For big, beautiful women, body image may play a role in intimacy. About one in 10 large women reported not having sex in more than a year, primarily due to concerns about potential partners seeing them naked.

In contrast, just 7-percent of Brits with a body mass index “within normal limits” said they had gone without sex for a year or more.

“Slimmer people do tend to feel more sexually confident,” sex and relationships expert Tracey Cox said. “It also stands to reason that the more you like your body, the happier you are to show it off to your partner. Slimmer people also tend to be healthier and fitter, which makes them more active and enthusiastic in bed.”

Even though they are more active sexually, size 8 women ranked their confidence at 5.7 out of 10, around the same as those who were a dress size bigger. Size 20 women rated their confidence as just 5, and size 24 women just 4. Fourteen percent of size 24 women said their confidence levels in the bedroom were just one out of 10, while only 5-percent of size 8 women said the same.

In total, 70-percent of women and 48-percent of men admitted they do all they can to avoid baring their bodies to their partners during sex. Some reported ingenious methods for sexual avoidance, including pretending to have had too much to drink and ensuring their partners are asleep before entering the bedroom.

According to Mandy Cassidy, a psychotherapist and consultant for LighterLife, “The study shows that being obese affects the mind as well as the body and reveals the problems faced by so many people. For many it’s a vicious circle: Many use food as a substitute for love, and as the pounds pile on, their relationship switches from their partners to food.”