We all know that eating too much and exercising too little makes you gain weight (yawn!), but what many people don’t know is that are all sorts of other more subtle ways that it is all too easy to pile on the pounds. From the friends you have to the relationship you’re in, to whether you eat breakfast and what time you go to bed at night; all of these can have a huge impact on whether you are the size and shape you want to be.

Here are the most surprising things that make you overweight.

1. Starting A New Relationship.

It’s great being in love, but all those romantic meals dinners-for-two can really take their toll on your weight. A recent US survey found that 47% of women said they gained weight in a happy relationship, compared to when they were single. And the effect was greater either than giving up smoking or even having a baby.

Another UK survey pinpointed five different weight stages to a relationship. Stage one, the early dating stage, saw women lose an average of 5lbs (this is when you’re scared witless about taking your clothes off in front of your new man). Stage two, the honeymoon stage, is when women start to inflate, by an average of 10 lbs. They may then lose it in the run up to a wedding, but put it back on again if they have children.

What to do: Don’t ditch the fitness regime just because you’ve met Mr Right.

2. Your Contraception.

Doctors insisted for years that the pill didn’t cause weight, but women knew different and now, finally, there is an acknowledgment that the pill can have an impact on your waistline. This is in part because some pills, called ‘combined’ pills, contain oestrogen, which interacts with insulin, a fat storage hormone. ‘Mini’ pills are progesterone only, but there is anecdotal evidence that they can be a factor in low mood, which we all know causes over-eating.

Injectable contraceptives (Depo-Provera) have the worst reputation for weight gain and even if you have them removed the effect can last for up to a year. IUDs don’t appear to affect weight, although there is a risk of infection and so many doctors do not recommend them for women who have not already had children.

What to do: Try condoms

3. Skipping breakfast.

It may seem basic calorie maths that if you skip breakfast, you reduce your daily energy intake so you’ll lose weight, but the opposite is true. Scientists at Imperial College, London, scanned the brains of two groups of volunteers, one of which had skipped breakfast. This group’s brains reacted far more positively to pictures of high calorie foods such as pizza than the breakfast-eating group. The breakfast skippers also went on to eat 20% more calories at lunch.

What to do: Eat a breakfast of protein and complex carbssuch as boiled eggs and wholemeal soldiers.

4. Snacking.

It’s become dieting lore that we need to eat three meals and two snacks a day to lose weight. The argument is that leaving long gaps between meals causes our bodies to think we’re starving and so store more of the calories we do eat as fat. However, this rule actually comes more from body building, where competitors routinely munch on chicken breasts at all hours of the day and night, than medicine. As an endocrinogist if the body can cope with 5 – 6 hours not eating and they will say: ‘of course’. Otherwise, we’d all starve to death in our sleep.

Eating snacks can be helpful if it stops over-eating at the next meal, but only if these snacks do not increase the overall daily calorie load.

What to do: Keep snacks under 150 cals e.g an apple and 2 Brazil nuts.

5. Wine O’Clock

You know how it is. You’ve had a busy day at work, or you’re facing the busy mum’s the kiddie bedtime routine. You deserve a glass of wine, or three, don’t you? However, a daily wine habit can really pile on the pounds, for four reasons. First, the calories. A glass of wine can have anything from 150 to 250 calories. Three of those and you’ve drunk your supper.

Second, alcohol is basically refined sugar and so upsets blood sugar. This can cause weight gain in itself. Third, alcohol puts stress on your liver. This can make the liver less efficient at detoxing other things, notably female hormones. Unbalanced female hormones also cause weight gain. Last alcohol weakens your resolve around food, so you may end up eating food that is less healthy for you.

What to do: Find another way to unwind at the end of the day, such as a trip to the gym, or just a cup of herbal tea.

6. Your friends
It may seem unfair to blame your friends for your weight, but according to a 2010 study from The University of Harvard in the US, if you have four or more overweight friends you are twice as likely to be overweight yourself. Psychologists think there are two reasons for this. First, your perception of a ‘normal’ weight may be shifted by spending time with bigger people. Second, a concept called: ‘behavioural contagion’. This is when you ‘catch’ behaviour, such as eating unhealthy foods or large portions, from others.

What to do: you don’t have to ditch all your mates, but make a point to hang out with some slim people and copy them as well.

7. ‘Healthy’ Takeaways.

We all know that curries, kebabs and pizzas are the quick route to weight gain, so many of us try to choose ‘healthier options’. However, some of these can be much more fattening than you think. Sushi is marketed as the ultimate health food, but the rice is highly refined white rice and is also sweetened with sugar, so it will stimulate the release of fat storage hormone insulin. Some sushi also comes with hidden mayonnaise. One plate, or 2 – 3 pieces, of California roll (avocado, salmon and mayonnaise) comes in at a whopping 255 calories. Most of us may eat three to five plates of that.

Asian food has a far ‘healthier’ image than Indian and yet chicken katsu curry from Wagamama has 800 calories, the same as an average chicken tikka masala from the neighbourhood curry house. Even salads can add up. You may feel really virtuous if you order a vegetable and goats cheese salad at Pizza express, but it has a scary 866 calories.

What to do: Eat at home more. You can control added fats and sugars, plus you’ll save money.

8. Your social life.

Hibernating under the duvet all weekend with a hangover, rather than getting to the gym, is not the way to shift the flab. However, even if you don’t go mad on Jagerbombs, going out too much and skimping on sleep can cause weight gain.

A US study from 2011 showed that just one night of reduced sleep can slow down the metabolism, meaning that you burn fewer calories doing the normal stuff like breathing. And the bad news doesn’t end there. Another study found that sleep deprivation raises stress hormones that can cause weight gain and increases appetite because it alters another hormone, called Leptin.

What to do: If you go out, make sure to get back and be in bed at a decent time.