"Clean eating" is associated with the healthy lifestyle and body beautiful that is promoted by many online bloggers. While the term is heavily used in social media, there has never been any agreement on what it really means or any comprehensive studies examining the potential benefits of a clean eating lifestyle as a whole.
However, the core principles that the big names in this movement champion appear to be: eliminate processed food; reduce salt intake; eat more vegetables; choose whole grains; eliminate refined sugar; reduce alcohol. For some, you also need to be gluten, dairy, and soya free and to eat raw (depending on how militant you are, food has to be entirely uncooked or only mildly heated). And if you want to be completely "clean" you should probably be vegan, too. Quite a list, then.
And there are also some big players online - including Food Babe, who was voted by Time Magazine as one of the 30 most influential people on the internet - who have significantly influenced this trend.
While some of the principles of clean eating are in line with the best available evidence for losing weight or preventing ill health - such as eating plenty of fruit and vegetables, sticking to wholegrains and limiting processed food - there are plenty of others that don't stand up to scrutiny. It has been repeatedly proven that dietary restrictions such as a dairy-free diet or gluten-free diet are nutritionally substandard and studies have linked the introduction of a gluten-free diet with increased levels of psychological distress in coeliacs including depression and anxiety.
Some people find it difficult to understand why dietitians and doctors are against the clean eating phenomenon when there are still people eating burgers for breakfast and obesity is on the rise. However, some clean eating is sensationalist promotion of non-evidence based, and extremely restrictive, lifestyles that demonise everyday food essentials. And that can lead followers into having a sense of shame and failure for not eliminating "unclean" foods 100% of the time - so you can see where the negativity from healthcare professionals stems from.
There is significant research disproving many of the principles of the diet. Below are some of the big claims and why they don't stack up.
Clean eating can cure disease
Some clean eating bloggers claim to have cured themselves of diseases. The kinds of medical conditions that clean eating is supposed to cure are often conditions that are not well understood, such as chronic fatigue, which leaves sufferers desperate for a solution. And where there is desperation there is always someone willing to sell help - however unscientific.
One of the big names in clean eating who believes her diet controls her PoTS - where standing up causes a drop in blood supply to the heart and brain and the heart races to compensate - intestinal issues and headaches through her method of a dairy free, gluten free vegan diet is Deliciously Ella. PoTS, however, has no proven link with food except that a higher salt intake is recommended to help keep blood pressure up. Having too little salt in the diet can exacerbate the problem. The reason that Ella is so much better now is much more likely to be age-related as we know that for 80% of sufferers, symptoms disappear between the ages of 19-24. Ella was diagnosed aged 19 in 2011 and has been blogging about diet for four years.
One thing diet may have helped with though is Ella's gastroinestinal issues. Her method of eating has a diet that is very low in fermentable carbohydrates or FODMAPs which have been robustly proven to be a cause of Irritable Bowel Syndrome (IBS) which affects up to one in five people.
Clean eating makes you happy!
Many of the clean eating bloggers promote themselves as a model of how you could look if you follow their lifestyle. But it is important to remember that it is their job to look the way they do. If you have a full-time job and a busy life, the chances of you cooking every meal from scratch, never having to grab a sandwich from the supermarket for lunch and being able to work out for two hours a day are very slim. If you try to model your life on theirs you are more than likely to end up feeling like a failure because it is simply not realistic.
Interestingly, many clean eating bloggers claim to have been depressed before clean eating. There has been lots of research into dietary treatments for depression by increasing an amino acid called tryptophan which is a precursor for serotonin production in the brain, which in turn influences good mood. To date, no trial has conclusively proven that increasing dietary tryptophan improves serotonin production or depressive symptoms but a diet in line with clean eating actually has the potential to be low in essential amino acids such as tryptophan.
What is more likely is that all the attention and apparent public approval received for losing weight and improving their appearance has temporarily improved their self-worth.
Clean eating is a good way to lose weight
Clean Eating Alice, 23, is another big name in the game. Alice isn't vegetarian but her diet is very low in carbohydrate. She claims that her diet and exercise regime has immeasurably improved her health and happiness. It was reported that through her version of clean eating and intensive exercise, she dropped 2st 7lb (16kg) and reduced her body fat percentage from 30% to just 15%.
Alice's reported body fat percentage is concerning. The minimum essential fat for a woman is between 10-13% - we need this amount to maintain our immune system and maintain healthy hormone levels. Many professional athletes will have a body fat percentage of up to 20% with the normal healthy level around 25%. So holding herself up as a realistic and achievable role model is highly misleading.
Clean eating is good for gut health
The Helmsley Sisters were some of the first to bring the clean eating trend to our attention. Their philosophy aims to help people with their digestion and relationship with food, and teach the importance of gut health. Their recipes eliminate gluten, grains and refined sugar (and minimise natural sugars). However, the majority of people tolerate gluten very well - the exceptions are for people with conditions such as coeliac disease - sugar is absorbed so efficiently it has no impact on digestion and grains provide high levels of prebiotics to feed the good bacteria in your gut. The best thing for gut health is a good, balanced diet.
Clean eating prevents ageing
Many bloggers state that clean eating will keep you looking youthful. There is some compelling evidence that antioxidants found in fruit and vegetables can prevent premature skin ageing.
You do, however, also need plenty of good quality protein to maintain the integrity of your skin and therefore extreme clean eating could easily undermine the benefits of the antioxidants.
Clean eating will detox your body
Detox diets are all the rage and the clean eating crew all have their own version of a detox diet. Fortunately, no one needs a detox diet because our liver and our kidneys are always already doing this. Everyone would agree that excessive consumption of highly processed food with lots of additives is not a healthy way to eat. However, neither is following a highly restrictive diet for any amount of time and there is certainly no health benefits associated with "detoxing".
Some clean eaters promote an alkaline diet to prevent excess acidity in the body. Ironically, our stomach acid is only slightly less acidic than battery acid so anything you eat will be immediately placed into a highly acidic environment where the pH is tightly controlled. You cannot manipulate your body's pH through diet (as the below tweet suggests) and you don't need to try.
Clean eating makes you healthier
There are even more extreme examples of clean eating out there including Freelee The Banana Girl who promotes a raw vegan diet of 15 bananas, 40 pieces of fruit and a couple of kilograms of potatoes a day. She claims that eating this way has cured her weight issues, depression, irritable bowel syndrome, chronic fatigue, poor digestion and acne.
It is hard to pin down the most concerning thing about this diet but the fact that Freelee is consuming 6.5 times more potassium than is recommended and encourages others to do so is a big one. She even consumes 30% more potassium than is shown to cause excess potassium in the blood, which can lead to deadly changes in heart rhythm. That said, whether or not she is absorbing any of the nutrients in her food due to the amount of fibre she is taking in is questionable and if her bowel habits are normal and healthy it is a medical miracle.
Anyone can call themselves a nutritionist and there are many quick courses that give a false air of credibility. There are also no regulations around what people can and can't recommend as being healthy. It should be very hard to maintain a voice of authority in an area in which you are totally unqualified and in a world where your self worth depends on "likes" and "views" and "followers".
An obsession with clean eating and the shame that is often associated with eating foods considered to be dirty can also lead to mental health issues such as orthorexia, an eating disorder associated with obsessive healthy eating. Emmy Gilmore, clinical director of eating disorders clinic Recover, even suggested in a recent BBC documentary that many UK clean eating bloggers had sought help from her clinic. So rather than watch videos of supposedly physically healthy girls as gospel, it's better to develop healthy eating habits that come from sound scientific advice and which balance all the nutrients your body needs.
And if you're seeking professional advice, find a nutritionist with a degree or a registered dietitian - it's a protected title so you can be certain that the advice you're given will be scientifically robust.