There's no denying that December is a foodies paradise. With rich meats, fruity wines, sweet treats and heavy puddings. Then January 1st comes around all too soon, back to work, kids to school and hopefully back to the gym. On average 30% of the UK population is on one diet or another, in January it peaks to around 45%. With so many diets to choose from and so much dis-information being touted as "science", which is the best diet for health and fitness? We've picked 5 of the most popular and test which, if any, you should follow.
The 5:2 Diet
First conceived a few years ago by Doctor Michael Mosley, whilst conducting research into diet for a BBC documentary. Intermittent fasting may not be all that new, but Dr. Mosley put it into the 5:2 format and made it a hit, cashing in on the hype following the TV shows airing and subsequent book release.
The 5:2 diet is based on a principle known as intermittent fasting (IF) – where you eat normally for five days a week and fast on the other two days. On top of losing weight, disciples of the diet claim the 5:2 diet can improve lifespan and brain function, and protect against conditions such as dementia and Alzheimer's disease.
However, evidence on the effectiveness of the 5:2 diet is limited when compared with other types of weight loss techniques. A 2010 study found women placed on a 5:2 diet achieved similar weight loss to women on a conventional calorie-controlled diet, and were also less likely to develop type 2 diabetes. There is however growing evidence that the 5:2 model may help lower the risk of certain obesity-related cancers, such as breast cancer.
Sticking to a regimen for two days a week is more achievable than seven days, so you are more likely to persevere with this way of eating and successfully lose weight. Two days a week on a restricted diet can lead to greater reductions in body fat, insulin resistance and other chronic diseases.
The non-restricted days do not mean unlimited feasting. While you don't need to be as strict about your calorie consumption, you still need to make healthy choices and be physically active.
Fasting days could make you feel dizzy, irritable, give you headaches and make it hard to concentrate, which can affect work and other daily tasks. Common side effects are difficulties sleeping and daytime sleepiness, bad breath, and dehydration.
The 5:2 is a simple way to reduce calorie intake. There are lots of versions of this diet, with some less safe than others. Many studies on intermittent fasting are short-term, involve small numbers of subjects, or are animal-based. If you're keen to try it, choose an evidence-based plan based on healthy, balanced eating and at least written by a dietitian. It's pivotal to avoid nutritional deficiencies, dehydration and overeating on non-fast days.
The Dukan Diet
The Dukan diet is a low-carbohydrate (carb), high-protein diet. There's no limit to how much you can eat in each of the diet's four phases, provided you follow the rules of the plan. In phase one, you're on a strict lean protein diet. This is based on an approved list of 72 low-fat protein-rich foods, chicken, turkey, eggs, fish and fat-free dairy. This is for five days to achieve quick weight loss. Carbs are strictly off limits, except for a small quantities of oat bran.
Unlike the Atkins diet, Dukan's phase one bans vegetables and seriously restricts fat. The next three phases see the gradual introduction of fruit, veg and carbs, and eventually all foods. The aim is gradual weight loss of up to 2lb a week and to promote long-term weight management. There's no time limit to the final phase, which involves having a protein-only day once a week and taking regular exercise.
You can lose weight very quickly, which can be motivating. It's a very strict and which agrees with some people. It's easy to follow, and you don't need to weigh food or count calories. Apart from keeping to low-fat, low-salt and high-protein foods, there's no restriction on how much you can eat during your first two weeks.
At the start of the diet, you may experience side effects such as bad breath, a dry mouth, tiredness, dizziness, insomnia and nausea from cutting out carbs. The lack of wholegrain, fruit and veg in the early stages of the diet could cause problems such as constipation. The high quantities of animal protein in this diet, combined with potential dehydration are high risk markers for kidney stones and other renal problems.
The rapid weight loss can be motivating, but it is unsustainable and genrally unhealthy. The Dukan diet isn't nutritionally balanced, which is further proved by the fact you need a vitamin supplement and a fibre supplement. There's a danger this type of diet could increase your risk of long-term health problems if you don't follow it strictly. The diet lacks any variety, so there's a high risk of getting bored quickly and quitting.
The paleo diet or caveman diet, consists of foods that can be hunted and fished i.e meat and seafood; and foods that can be gathered – such as eggs, nuts, seeds, fruits, vegetables, herbs and spices. It's a plan based on the supposed eating habits of our hunter-gatherer ancestors during the paleolithic era, before the development of farming around 10,000 years ago. That means common cereal grains such as wheat, dairy, refined sugar, potatoes and salt , as well as anything processed are strictly off the menu. There is no official "paleo diet", but it is generally seen as a low-carb, high-protein diet, with some variations on carbohydrate and meat sources.
Followers say the paleo diet is "one of the few long-term healthy eating plans that can help you lose weight and reduce your risk of diabetes, heart disease, cancer and other health problems". Most studies on the diet are small, and more long-term research would be needed to show conclusively whether or not it is as effective as some people claim. A 2014 Liverpool University study found similar weight loss between participants on a paleo diet and those on a low-fat diet after two years. Interestingly, participants on the paleo diet did have slightly better levels of triglycerides, a type of fat linked to heart disease.
The paleo diet encourages you to eat less processed food, more fruit and vegetables. Reducing your intake of high-calorie foods will inevitably reduce your calorie intake and help you lose weight. The diet is simple and doesn't involve calorie counting. Some plans go by the "80/20" rule, where you'll get 99% of the results if you adhere to it 80% of the time. This flexibility can make the diet easier to stick to and thus more successful.
There are obviously no accurate records of the diet our Stone Age ancestors ate, so the paleo diet is largely based on educated guesses, and its health claims lack scientific evidence. Most versions of the diet encourage large amounts of meat, which flies in the face of current health advice. Many versions ban dairy products and wholegrain, which form part of a healthy, balanced diet. Like all high-protein diets, the paleo can be expensive, depending on your choice of meat. It's impossible to follow without eating meat, seafood or eggs, so it's not one for vegetarians.
Most versions of the paleo diet exclude key food groups, increasing the risk for nutritional deficiencies unless careful substitutions are made, and use of dietary supplements may be necessary. The diet has some positive aspects, so an adapted version that doesn't avoid key food groups – such as wholegrains, dairy and legumes – would be a better choice. The diet seriously lacks variety, so there's a risk of boredom and quitting. If you're keen to impersonate our Paleolithic ancestors, there are far greater health benefits in mimicking their activity levels, rather than their alleged diet.
South Beach Diet
The South Beach Diet is a low-GI diet originally developed for heart patients. There's no calorie counting and no limits on portions. You're encouraged to eat three meals and two snacks a day, and follow an exercise plan. People who have more than 5kg to lose start in phase one. This is a two-week quick weight loss regime where you eat lean protein, including meat, fish and poultry, as well as some low-GI vegetables and unsaturated fats. Low-GI carbs are slowly re-introduced during phases two and three, designed to promote gradual and maintainable weight loss.
If you can avoid phase one and start on phase two, there are fewer dietary restrictions than some other popular diets. After phase one, the diet broadly follows the basic principles of healthy eating. No food groups are eliminated and plenty of fruit, veg and low-GI carbs are the order of the day.
The severe dietary restrictions of phase one may leave you feeling weak and you will miss out on some vitamins, minerals and fibre. You may initially experience side effects such as bad breath, a dry mouth, tiredness, dizziness, insomnia, nausea and constipation.
The first two weeks are by far the most difficult to get through. It's alarming that this diet promises such a large weight loss – up to 5.5kg – in the first two weeks. This, however, will certainly not be all fat. Some of the weight loss will include water and carbs, both of which will be replaced when you begin eating more normally. Once you get past the initial phase, the diet follows the basic principles of healthy eating and should provide the nutrients you need to stay healthy.