A new year means one thing for many people - standing on the scales, wishing the number revealed was a few pounds (or stone) lighter, and then embarking on the latest fad diet (only to be back on the beer and cakes two weeks later).
It's a ritual mankind has been practising for decades. In fact, much further back, in the early-1800s, poet Lord Byron was the first known 'celebrity' obsessed with dieting, and popularised a vinegar and water concoction to lose weight.
As we all attempt to embark on a healthier year, here's a look back at some of the popular - and sometimes downright crazy - diets through history (for nostalgia purposes only: we certainly don't suggest following them).
Back in the Thirties, it was claimed that grapefruit contains a chemical, called naringenin, that helps burn fat. Traditionally, the idea was that dieters had a grapefruit before every meal - but also cut their overall calorie-intake down by eating less sugar and carbs, and avoid certain foods like celery and white onion.
The grapefruit does contain naringenin and other good vitamins, of course. Jeraldine Curran, aka The Food Nutritionist (thefoodnutitionist.co.uk), says: "[Grapefruits contain] limonoids which act as antioxidants and promote the formation of a detoxifying enzyme.
This enzyme sparks a reaction in the liver that helps to make toxic compounds more water-soluble and allows them to be excreted from the body."
The diet had a resurgence in the Noughties, when Kylie Minogue championed the method, but scientists dispelled its effectiveness, saying you'd need to eat 40 grapefruits in one sitting for the 'fat-burning' chemicals to have any real impact.
Designed to help shed weight fast, this popular fad came with some serious health risks.
The concept was to spend a week eating unlimited amounts of super-low-calorie homemade cabbage soup. On some of the cabbage soup diets, people were allowed to eat other foods one day a week, but it was extremely limiting.
Dr Fatima Cody Stanford, from the Obesity Medicine and Nutrition Department at Massachusetts General Hospital and Harvard Medical School, says: "The cabbage soup diet was popular and effective over the short term for weight loss because it caused significant caloric-restriction. Most of the weight loss in the initial period is likely water weight, as opposed to fat stores.
"Eventually, you get hungry and revert back to your original eating plan as your body tries to compensate for food groups that were missing, especially protein."
Low-fat became synonymous with being healthy back in the Fifties and Sixties, when Dr Ancel Keys become known for the 'Diet-Heart Hypothesis', which claimed that saturated fat caused heart disease.
"Then in 1983, an article based on the Framingham studies was published, claiming obesity was an independent risk factor for heart disease. By 1984, even though the diet-heart hypothesis was only a hypothesis, it became the gold standard with regards to diet, and therefore was treated like it was proven," says Curran.
In the Eighties and Nineties, low-fat diets were promoted by healthcare professionals and became public policy.
"Fast-forward to 2018 and many healthcare professionals are now very sceptical of the low-fat diet, especially as rates of obesity have increased rapidly over the last 20 years," says Curran. "There is no clear evidence that a low-fat diet prevents heart disease or promotes weight loss."
Devised by cardiologist Robert Atkins, this plan recommended drastically cutting out carbohydrates like bread, pasta and potatoes, as well as nuts, seeds, lentils and starchy vegetables - but dieters could eat as much fat and protein as they liked, including in foods like bacon, mayonnaise and butter, the theory being that without carbs to burn, your body burns fat instead, releasing ketones that you use for energy.
The diet divided opinion when the first book was released in 1972, and now there are newer, less drastic versions available on the Atkins website.
Today, Atkins is still considered quite controversial but according to Curran, there were are some positives.
She says: "Believe it or not, Atkins had the right idea - his diet included healthy fats along with reducing the amount of starchy carbohydrates. The main problem with the original diet was the lack of vegetables.
"While you don't really need to have lots of meat in the diet, good quality meat, butter, eggs and oils have a role to play."
This fad advocated eating a lot of pineapple - also for its apparent 'fat-burning' qualities - when the original book was published in 1981.
Only fruit was allowed for the first 10 days of the plan, after which protein and carbs had to be eaten in separate meals.
"This diet worked on the premise that you needed to eat foods in a certain order, for the right combination of foods to lead to weight loss," says Dr Stanford.
"At this time, there is no scientific study to support the claims noted in this diet regimen. An important article in JAMA (Journal of the American Medical Association) spoke to many of the inaccuracies noted in the bestselling book about this diet, which were primarily in relation to the notion that this diet proposed primarily fruits with a small amount of salt.
"There is concern about significant loss of water weight, diarrhoea, increased heart rate, and muscle weakness associated with the extreme nature of this diet. These issues are probably why this diet is no longer popular."
It was in 1997 that claims surfaced that those with blood type A were thought to be better suited to vegetarianism, while people with blood type B could eat more dairy products.
"This diet works on the premise that blood type, in the ABO blood grouping, will impact the ability to digest lectins if someone eats food that is incompatible with their blood type," says Dr Stanford.
"To date, there is no scientific evidence that certain foods work better for one blood type over another."
As the name suggests, this diet doesn't just see processed foods banned from the menu, but any cooked food - instead sticking to raw, natural items.
"[The belief is] that this decreases the risk of diseases, such as cancer. However, there is a risk to infection from uncooked or raw foods," says Dr Stanford.
"There also may be deficiencies, such as vitamin B12. It is challenging to maintain a raw food diet, and as a result, it may be difficult to achieve meaningful and sustained weight loss."
So make sure you don't fall victim to the next diet fad this New Year.
Curren says: "The best advice is to follow the 'real-food' diet. Thereby eating a diet based around natural, whole foods which includes healthy fats - such as coconut oil, avocado, good quality fish and meats - along with lots of vegetables, while avoiding sugar, processed food and 'low-fat' food."