In all my years as an obstetrician and gynaecologist, I have seen many women of all ages, races, and even sizes, walk through my doors.

Each woman is unique, but I have observed a common trend among most of my patients - they tend to start putting on weight when they enter a relationship, start living together with their partner, or get married.

This has always been a running joke among married couples: "Wah, married already, put on weight ah!"

It turns out that this may not be a joke, but is actually reality.

Let us look at why this phenomenon is happening, and what women - or couples - can do about it.

Numbers don't lie

Many of the stories of women in relationships gaining weight are shared as anecdotes, but there is also scientific evidence of this trend.

In the US, the National Longitudinal Study of Adolescent Health looked at 7,000 young adults who were either single, dating, living with a partner or married.

The study found that women are at higher risk of becoming overweight when they are in a relationship.

Women who lived with their partners had a 63 per cent higher risk of becoming obese.

Marriage made obesity an even greater likelihood - women who were married were 127 per cent at higher risk of becoming obese!

Interestingly, men who co-habitated with their partners had less risk of becoming obese, though their risk also doubled when they were married.

In Australia, the Longitudinal Study on Women's Health found that being in a relationship and having a baby had the biggest impact on weight gain - the average weight gain was 9kg over a 10-year period, compared to single women who only gained 5kg in the same period.

Women with partners, but did not have a baby, gained an average of 6.8kg.

Love or love-handles?

How are relationships or marriage linked to weight gain in women?

One theory suggests that being in a relationship and living together brings about changes to a woman's eating habits.

She is more likely to eat regular meals and larger portions.

This could be due to the fact that meal times become an important part of a couple's routine together, and they tend to spend more time over the meal, rather than rushing through it as a woman would if she were eating alone.

Exercise and physical activity also reduce in a relationship, perhaps due to the fact that other leisure activities take over.

It has even been suggested that women may no longer feel the need to lose or maintain weight after they are in a relationship because they don't need to "attract a mate" anymore!

Some people critically refer to this as the woman "letting herself go".

In sickness and in health

It is ironic that we should be so negligent of our health during what could be the happiest period of our lives.

Some people still see weight gain as a sign of prosperity or contentment, but it is actually a health problem with serious consequences.

Women who are overweight or obese are at much higher risk of developing diabetes, heart disease, cancer and knee problems.

While we do not have to maintain a supermodel figure, neither should we "let ourselves go" to the point of obesity.

It is not about impressing your partner, but about staying healthy and well for life.

Of course, I am not suggesting that women should break off their relationships or remain single for the rest of their lives.

In fact, we should use our relationships to help us maintain a healthy body weight.

Exercise can be something that you and your partner do together, as a way of bonding and spending quality time with each other.

Make a gym or badminton date several times a week, instead of just going out to dinner or lounging in front of the television.

Exercise also works better when you have someone to motivate you, and who better to give you inspiration than a loved one?

Eating habits can also be modified through the power of two people.

Perhaps you and your partner can make a greater effort to cook at home, so that you can control the portions that you eat, and the amount of oil and fats used. Cooking can be a fun shared activity, instead of one person doing all the work and getting cranky.

When you eat outside, consider splitting your meal with your other half.

The serving sizes in restaurants or hawker stalls are often too large, so ordering one meal with a small side dish is often sufficient for two people.

A relationship is just like a partnership, and partners usually work better together. So work together with your husband or boyfriend to keep your weight at the right level.

Don't forget that lifestyle habits are formed at home, so being healthy in a relationship is not only important for you, but also for your children in the future.

Being in a relationship should enrich your life, not make you overweight and sick. Here's to living healthily ever after!

Datuk Dr Nor Ashikin Mokhtar is a consultant obstetrician & gynaecologist (FRCOG, UK). For further information, visit www.primanora.com. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader's own medical care. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.