If you are a restaurant diner, sticking to a healthy eating plan can be difficult. So, to help you to eat out without piling on the pounds we've come up 10 rules to stick to.

1. Sauces and dressings on the side

Where possible, always ask for any dressings and sauces to be served separately. This will enable you to add exactly the amount you want to your meal and avoid a meal smothered in a rich sauce. Choose tomato-based over cream-based sauces; as well as containing less fat and calories, tomato sauces contain the antioxidant lycopene, which may help prevent prostate cancer. Men should aim to have seven or more portions of tomatoes or tomato-based foods per week.

2. Don't be swayed by your friends

Don't be tempted to go for unhealthy options because that's what the other people are having.

And don't feel under pressure to cave in if others entice you to do so. You've got to remember that it's your body and the reason why you want to lose weight is to feel better about yourself, it's not for them. After a few occasions eating out they'll just naturally accept your new healthier approach and stop pestering you.

3. See the menu beforehand

If you know where you are going to eat a good healthy eating trick is to make your menu choices prior to getting to the restaurant. Making your selection early on will enable you to have plenty of time to select the healthiest choices, plus you'll be less likely to be influenced by your peers to make more unhealthy choices. So, go online or dig out the menu, make your selection and stick to it.

4. Limit the appetisers

Many restaurants provide some sort of pre-dinner appetiser — which is generally bread. Whilst bread isn't bad for you, it's something that you don't actually need to eat if you are going to eat a full meal as well. Also, if it takes some time for your main meal or first dish to arrive, you are in danger of polishing off a fair few portions. If you do have bread, the healthy approach is to opt for wholemeal varieties, just have one piece and hold the oil or butter.

5. Avoid the 'all-you-can-eat'

If you do have some say in the choice of restaurant try to avoid the 'all-you-can-eat' establishments. Granted, they are one of the most reasonable choices when it comes to budget but it's going to take a cast-iron will to stick to just one plate of the food. It might be a hard task to convince your fellow diners though so if you can't sway them be prepared, have buckets of willpower to see you through the taste temptation the 'all-you-can-eat' buffets provide.

6. Starter and a salad or a side

A good way to keep your meal sizes smaller is to order a starter as your main course but bulk it out by adding some sides. Go for a side salad, a serving of seasonal veg or both if you are particularly hungry. Just make sure you ask for your salads dressing free and hold the butter on the veggies.

7. Limit the alcohol

Alcohol contains a substantial 7 calories per gram (carbohydrates and protein both contain around 4 calories per gram) so you can see how your daily calorie quota can quickly accumulate if you are adding a few glasses to the mix. Try to limit alcohol as much as you can and drink a glass of water for every alcoholic one, this will enable your body to stay as hydrated as possible as well as fill you up.

8. Don't starve yourself

Don't starve yourself during the day to compensate for a planned indulgent evening meal out.

It's a common strategy and we've probably all done it. If you have your normal daily meals you'll arrive at the restaurant healthily hungry and not desperately ravenous. If you are really hungry you are far more likely to choose the most tempting and satiating foods which are more likely to be the less-healthy options.

9. Go for fish

Choose fish — white fish is extremely low in fat and is a great source of protein, while oily fish provides omega-3 fatty acids — a 'good' type of oil which has been shown to help protect against heart disease and may help prevent other diseases such as cancer. If you are not a fish fan, opt for lean meat, ideally chicken or turkey and go for grilled or baked as opposed to fried.

10. One or two but not three courses

If you can, try to stick to one or two courses instead of the full three. However if three courses are must, opt for a salad or soup to begin (vegetable soups are a great option; try to avoid cream-based ones) then go for fish or chicken as the main and finish up with a fruit based dessert or a sorbet. And watch portion size too — a study in the US found that portion sizes in food outlets had grown by up to 700 per cent in the last 30 years.