These are the dangerous diets to avoid in the New Year according to the NHS

NHS England medical director Professor Stephen Powis said using pills and detox teas have a "slim chance of success" and can cause serious complications.

Going on a diet is the most common New Year's Resolution and, although the NHS endorses getting in shape, Prof Powis advised against using diet pills, "tea-toxes", and appetite suppressant products, which can be harmful.

Products promising quick weight loss by reducing appetite and fatigue can have damaging side-effects, ranging from diarrhoea to heart problems, and can even interfere with oral contraception, causing unplanned pregnancies.

Prof Powis advised those wanting to shed a few Christmas pounds to lose weight "gradually and safely".

He said: "New Year's Resolutions are a great time to make a change, but the reality is there's a slim chance of success with diet pills and detox teas - and people could end up doing more harm than good."

This follows calls earlier this year for social media giants to crack down on celebrities posting misleading "get fit quick" adverts, prompting Instagram and Facebook to restrict endorsements of risky products.

Prof Powis recommended the NHS Long Term Plan, a 12-week weight-loss schedule to be used alongside an app, for those wanting to get in shape.

The NHS also offers a Diabetes Prevention Programme, and both of these regimes can be found on its website along with healthy recipes.

Health professionals also recommend the Couch To 5K app for first-time runners, Strength And Flex, and the NHS Fitness Studio apps.

Quitting smoking is the second most popular New Year's Resolution, and the NHS Smokefree app can help those wanting to cut down.

The Drink Free Days app is also recommended by the NHS for people wanting to try Dry January.

Prof Powis has also spoken out against so-called "party drips".

"At a time when health misinformation is running riot on social media, it is reckless and exploitative of these companies to peddle ineffective and misleading treatments, and those celebrities and influencers who help them do this are letting their fans down.

"People who are healthy do not need IV drips. At best they are an expensive way to fill your bladder - and then flush hundreds of pounds down the toilet - but at worst they can cause significant damage to your health.

"While many of us want to enjoy ourselves at this time of year, it is important to remember that nothing beats eating well and drinking sensibly when it comes to staying well, and a much better way to 'cure' a hangover is through drinking plenty of water and getting some fresh air.

"Miracle hangover cures and quick fixes simply don't exist, and anyone online who says they do is probably out to make a quick buck at your expense."