London, Dec 1 (IANS): Do you want to look your best during the festive season? Drop those extra pounds by opting for suitable celebrities' diets.

Mirror.co.uk reports that experts have assessed the diets Megan Fox, Jennifer Aniston, Pippa Middleton and Holly Valance swear by.

Pick the plan that's right for you and drop a dress size in time for Christmas:

Top nutritionist Angela Dowden gives her verdict on which ones work best.

1. Weight Watchers - loved by Patsy Kensit

How it works: Sign up and follow joined Weight Watchers' ProPoints plan. Every food is worth a different number of 'points', all of which add up to your weekly limit. Your limit will depend on your personal health and weight loss goals.

The expert says: “Weight Watchers is nutritionally sound and gets the thumbs up from docs. You're encouraged to eat lots of fruit and vegetables and nothing's banned.

"Instead you think about the quality of what you eat in terms of how it curbs your hunger rather than just counting calories. There's a big emphasis on group support too which helps a lot of people.”

2. Paleo Diet - loved by Megan Fox and Gary Barlow

How it works: The diet is based on the principle that we should eat the way we did back in the Paleolithic era - i.e. if a cave man wouldn't have eaten it, neither should you. All cereal grains are banned, as are dairy products, processed foods, beans and potatoes. But there's good news for meat-eaters. Paleo encourages you to eat your fill of meat, fish and eggs, accompanied by fresh fruit and vegetable. And there's no strict plan, it's just a case of sticking to the right foods.

The expert says: “If you can't bear going without the carbohydrates it's definitely not for you. But having a bit more lean steak, salad and sweet potato is delicious and can make weight loss seem less painful.”

3. 5:2 Diet - loved by Jennifer Aniston, Beyonce and Phillip Schofield

How it works: Eat normally for five days and 'fast' for two, cutting down your calorie intake to just a quarter of the usual daily amount. This adds up to 500 for women and 600 for men. It's been one of the most popular diets of the last year.

The expert says: “Grab yourself a 5:2 cookery book for inspiration and you can still enjoy gourmet food even on your 'fast' days off. It's also one of the few that's had proper medical research done into it.”

4. Dukan Diet - loved by Carole and Pippa Middleton

How it works: There are four phases:

The Attack Phase: For two to seven days, limit foods to those high in protein. Stick to lean meats, fish and eggs and non-fat dairy products. Tofu and quorn are also ok.

Cruise Phase: Add in vegetables. You can alternate veggie days and meat days or eat them together. No starchy vegetables like potatoes allowed. Grains and pulses are also off the menu, as is fruit (for now). Stick to this until your target weight is reached.

Consolation Phase: This slowly reintroduces 'normal' foods without you piling the weight back on. Add two slices of bread and one portion of fruit and cheese to your daily diet. You can also allow yourself two servings of carbohydrates and two “celebration” meals a week. For every pound lost during the Cruise Phase, stay in the Consolation Phase for five days. So if you have lost six pounds, do it for 30 days.

Permanent Stabilization Phase: Eat normally again six days a week. Once a week have a protein-only day as you did in the Attack Phase.

The expert says: “You have to be seriously dedicated to try this diet. Be aware that cutting out food groups can lead to deficiencies, so you may need to take a multivitamin.”

5. Clean and Lean Diet - loved by Holly Valance and Hugh Grant

How it works: The key is to stick to fresh, unprocessed foods, as close to their natural state as possible. For example, a chopped apple still looks like an apple while a crisp or chip looks nothing like a potato. If something is unrecognisable, it's probably been heavily processed - avoid. Artificial flavours or preservatives are a no-go so it's goodbye ready meals and takeaways. Foods should generally contain fewer than five or six ingredients to ensure they're as natural as possible. There is no exact plan. Eat three meals a day and try to include three key elements: protein in the form of lean meat or fish, fat in the form of avocado, nuts, seeds, and olive or coconut oil, plus vegetables. A rainbow of different colours ensures you're getting different vitamins and minerals so fill your plate with spinach, peppers, broccoli, and sweet potatoes.

The expert says: “The essential principle - cutting out processed foods and eating lots of healthy greens - is good. You shouldn't go short of nutrients and because there's bulky veg you'll feel full. You don't have to cut out carbs either, try to have some brown rice, quinoa, lentils and you'll be really healthy. You still need to watch portion sizes and how many homemade smoothies you have.”