Eating like a caveman, endless bowls of cabbage soups, low-acid regimes - the number of diets promising a slimline figure could confuse even the keenest dieter.
Here are some of the most popular diet plans of recent years - but be warned potential drawbacks include smelly breath, constipation and nausea.
:: 5:2 Diet
Based on the principle of eating normally for five days and fasting on the other two days each week.
During the five days, dieters still need to eat healthily and watch their calorie consumption and be physically active.
However, skipping meals can cause dizziness, irritability and headaches, and can affect concentration.
Other reported side effects include difficulty sleeping, bad breath and dehydration.
:: Dukan Diet
A low-carbohydrate, high-protein diet based on four phases. There's no limit to how much you can eat as long as you stick to the rules.
Phase one includes a strict lean protein diet of 72 low-fat protein-rich foods such as chicken, turkey, eggs and fish.
Carbohydrates are off-limits except for a small amount of oat bran.
The next three phases see the gradual introduction of vegetables, fruits and carbs.
Dieters can be easily motivated by this diet as it enables rapid weight-loss, but the side effects can include bad breath, dry mouth, tiredness, nausea and constipation.
:: Atkins Diet
A low-carbohydrate, high-protein programme starting with two weeks of low-carb foods for rapid weight-loss.
In contrast to the Dukan diet, Atkins allows unlimited fat and some vegetables to be eaten during phase one.
The next three phases see gradual weight-loss - and regular exercise should be taken.
The final phases introduce more carbohydrates, fruit and veg to help maintain a healthy weight.
This diet can be appealing to some men because it doesn't restrict dairy foods or alcohol.
However, possible side effects are bad breath, nausea and constipation, and the high intake of saturated fat could increase the risk of heart disease.
:: Alkaline Diet
Has many celebrity fans and is based on the principle that our bodies produce too much acid, the excess of which is turned into fat.
This diet recommends cutting back on acid-producing foods such as meat, wheat and dairy products, and eating more alkaline foods – mainly fruit and vegetables.
The regime follows an 80/20 rule consisting of 80% fruits and vegetables, and 20% grains and protein.
This diet is seen as good healthy eating advice, but nutritionists don't recommend cutting out whole food groups.
:: Cambridge Diet
Focuses on people buying and eating a range of meal-replacement products.
There are six diet plans, ranging from 415 calories to 1,500 or more calories a day depending on the goal, as well as a long-term weight management plan.
The products consist of bars, soups, porridges and shakes to be used as the primary source of nutrition.
Weight-loss on this programme can be sudden and although the meal replacements are all nutritionally-balanced, the vitamins and minerals required don't come from real food.
Side effects have also been noted as bad breath, dry mouth, insomnia, nausea and constipation.
The plan is not designed to be done over a long period of time.
:: Paleo Diet
Based on the supposed eating habits of cavemen and the most searched diet on Google in 2014.
It consists mainly of foods that can be hunted and fished, such as meat and seafood, and foods that can be gathered, such as eggs, nuts, fruit and vegetables.
It encourages dieters to eat minimal processed foods and more fruit and vegetables.
Like most high-protein diets, it can be expensive, which may mean people abandon the diet before seeing any long-term weight loss.
:: Cabbage Soup Diet
This seven-day plan consists of mainly eating cabbage soup alongside a small selection of other foods.
It's a very low-fat, high-fibre option and attracts dieters because of the rapid weight-loss it causes, as well as its low cost.
However, nutritionists argue that when the diet is over, weight gain can be rapid once normal eating has resumed which can de-motivate people to eat healthily.
The lack of protein and carbohydrates make it nutritionally unbalanced and vitamin supplements are recommended.
:: Vegan-Before-6pm Diet
This was invented by a food columnist who was told he needed to lose weight, so he ate like a vegan until 6pm every day.
It focuses on restraint, with dieters eating just plant-based foods until 6pm. However, dieters have to resist the urge to binge on unhealthy foods in the evening.
:: Raw Food Diet
Based on the belief that cooking food breaks down enzymes, causing it to lose a lot of its nutritional value.
The diet focuses on only eating vegetarian foods which are cooked or heated no higher than 48C (118F). It was originally praised for its focus on eating raw foods, but is now seen as unsustainable.
:: Weight-Watchers
A well-known diet which focuses on losing weight through diet, exercise and a support network of other dieters.
The diet is based on a points system which is calculated on a dieter's current weight.
Each food carries a certain number of points and dieters count points instead of calories.
Dieters attend weekly meetings and "weigh-ins" where nutrition, exercise and conversation with other dieters take place.
Some female dieters tend to find this the best route to weight-loss, preferring to lose weight alongside other people.
