We all know the feeling: Christmas and New Year have been and gone and you're left with a new-found determination to be healthier and fitter than ever before.
With a variety of diet plans to choose from, it's usually the easiest one with the fastest results we decide to follow.
But could your quest for a quick fix be doing more damage than you realise?
Leading dermatologist Dr Daniel Glass, from The Dermatology Clinic London on Harley St, discusses the negative effects crash dieting and extreme exercise can have on your skin and hair, reports The Daily Mail.
1) Hair-raising issues
Crash dieting may help weight loss in the short term, but it can also have a number of negative effects on your body, including hair loss. Everyone's hair goes through a growth cycle, called the "telogen phase", which is a period of time when the hair stops growing and sheds.
Approximately 10 per cent of your hair is in the telogen phase at any one time, and this results in normal shedding levels of between 30 and 150 hairs every day.
If you are under severe stress, either physically or emotionally, this can cause you to lose your hair, which is a condition known as "telogen effluvium".
Compared with the average loss, during this phase up to 30 per cent of your hairs may enter the telogen (shedding) phase of the growth cycle, resulting in excess hair loss.
It has been well documented that a cause of enhanced hair loss may be due to excessive and or extreme dieting and associated weight loss.
2) Lack of red meat and carbs is BAD for your skin
The potential long-term effects of dieting on your skin depends on exactly what type of diet is being followed, how long it is adhered to and your nutritional status before starting the diet.
If an unusual diet is adhered to for long enough, then there is a greater risk of nutritional deficiencies developing.
Most crash diets advise the user to limit or cut out foods such as red meat, wholegrains and breakfast cereals – all of which are good sources of iron.
Prolonged limitation of these foods could lead to an iron deficiency which may result in itchy skin, hair loss and a sore tongue.
To ensure that this doesn't happen make sure you keep an iron-rich diet which is still healthy and allows weight loss.
3) Too much exercise too soon could give you acne
A type of acne that can occur when starting a new fitness regime is known as Runner's acne; a sub-type of acne that occurs at the site of repeated friction or mechanical trauma, eg on skin under headbands, tight bra straps or waist bands.
This type of friction differs from heat rash and forms either a basic acne spot; a blackhead or whitehead, which can go on to produce inflamed pustules or papules.
In contrast heat rash is monomorphic (ie one shape); the rash is all uniform red bumps on the skin which can be itchy.
Acne generally tends not to be itchy, but can vary from person to person.
4) Lack of vitamins can crack your lips and change your skin
Whenever an overly restrictive diet is followed many will cut out vital foods that ensure are vitamin requirements are met.
A vitamin A or K deficiency can cause changes in the skin color and bruising and a Vitamin B deficiency may result in a sore, red rash at both sides of your lips.
As a whole, it would be far more sensible to avoid crash dieting and aim to incorporate a steady, healthy diet, with a variety of protein, fruits and vegetables, into your diet each day.
Not only would this be better for your physical, and mental, wellbeing, it would also help to make this a continual lifestyle change as opposed to a New Year's resolution that is destined for failure.