IT'S likely you'll put on weight over the festive season - and equally likely you'll struggle to lose it.

But many people will still embark on New Year diets, possibly losing a bit of timber, and then putting it back on again, in the classic yo-yo fashion.

However, although such yo-yoing is very common, new research suggests it could also be dangerous.

DEATH RISK

A US study found women in the 'normal weight' range who lost and regained weight had about a three-and-a-half times higher risk of sudden cardiac death - where the heart's electrical system abruptly stops working - than women whose weight remained stable.

Yo-yo dieting was also associated with a 66% increased risk of death from coronary heart disease, where blood vessels to the heart become blocked with fat, in the normal weight women.

The research, which studied more than 158,000 post-menopausal women over an 11.4-year period, didn't find an increase in either type of death among overweight or obese women who yo-yo dieted, otherwise known as 'weight cycling'.

"Weight cycling is an emerging global health concern associated with attempts of weight loss, but there have been inconsistent results about the health hazards for those who experience weight cycling behaviour," said Dr Somwail Rasla, lead author of the study at Brown University.

WHAT'S GOING ON?

The research didn't explain how yo-yo dieting might increase the risk of death, but Rasla suggests it could be connected to the possibility that, as people gain weight, cardiac risk factors, such as blood pressure and glucose levels, often increase, and the body eventually makes adjustments to compensate for the changes.

But when people yo-yo diet, the body may not have time to make those adjustments.

Another theory, developed after a trial using mice, suggests yo-yo dieting may have an impact on DNA. "We found that mice exposed to weight cycling behaviours ended up with damage to their DNA," notes Rasla.

DON'T DITCH THE DIET!

However, if you're overweight, it's not wise to completely abandon diets either, as evidence shows that being overweight in mid-life also increases the risk of dying from both types of heart disease.

The best solution, therefore, has to be to embark upon a healthy diet which aims to achieve a steady, regular, small weight loss, rather than the rapid, major loss that a crash diet aims for.

Nutritionist Cassandra Barns points out that as well as negatively impacting physical health, crash diets followed by weight gain can affect mental health, leading to guilt and low self-esteem.

"This can result in an unhealthy relationship with food," she warns. "By cutting back on calories to extreme levels while yo-yo dieting, you can be at risk of malnourishment, and you may be more tempted to overindulge in the likes of alcohol when 'off' your diet.

"Also, when our weight fluctuates regularly, we often diminish muscle mass, which is crucial for a high metabolic rate when resting."

SEVEN YO-YO-PROOF TIPS FOR HEALTHY WEIGHT LOSS

1. Don't starve yourself

If you miss meals or starve yourself, your body will think there's a shortage of food and its response will be to slow down your metabolism and hold onto fat stores. "This type of eating can lead to cravings because blood sugar will be low and your body needs a quick fix," says Shona Wilkinson, a nutritionist at the health and wellbeing shopping site SuperfoodUK.com.

2. Skip fad diets

"Fad diets, especially those that miss out whole food groups, may work temporarily but are usually too difficult to maintain for more than a couple of weeks," says women's health nutritionist and author Dr Marilyn Glenville.

3. Add protein to each meal

Protein slows down the rate the stomach processes food, and slows the passage of the carbohydrates with it, says Wilkinson. "As soon as you add a protein to a carbohydrate, you change it into a slower releasing carbohydrate, which will make you feel fuller for longer," she explains.

4. Don't eat on the run

Eating while rushing out and about gives your body the message that time's scarce and you're under pressure and stressed, says Glenville. "Furthermore, your digestive system will be less efficient. Make a point of sitting down and eating your food as calmly as possible," she advises.

5. Never Skip Breakfast

Sleeping makes your metabolism slow right down, and breakfast gets it going again. But it's important to choose healthy breakfast options, such as wholegrain cereals like porridge, or natural dairy products like yoghurt, eggs and fruit. Sugar-laden cereals will make blood sugar rise sharply and drop rapidly, making you feel more hungry quickly, explains Wilkinson.

"The old saying is that breakfast is the most important meal of the day. When you have breakfast, you're literally 'breaking the fast'. But always remember that just as important as having breakfast itself, you need something that will sustain you and keep you feeling fuller longer," she notes.

6. Eat little and often

Keep blood sugar and energy levels stable by eating something every three hours. Eat breakfast, lunch and dinner, plus a mid-morning and mid-afternoon snack. Try not to eat carbohydrates after 6pm. "This will stop those rollercoaster highs and cravings for sweet foods," explains Glenville. "Because your blood sugar isn't allowed to drop, your body will no longer have to ask you for a quick fix. As the blood sugar steadies, so will mood swings."

7. Don't cut out all fat

Fat is an essential part of the diet and shouldn't be avoided, stresses Glenville. However, fat needs to be the right kind, from oily fish, nuts, seeds and seed oils, to get essential omega-3 and 6 fats which are necessary for health. "What we should be avoiding are the processed fats found in junk food and bakery products," she adds.