Detox diets are out – but do UPFs mean we are still at risk from toxins?

If you didn’t pluck your eyebrows razor-thin, cover yourself in body glitter or go on a detox diet, did you really live through the 90s? Although fashions have changed, the trend for detoxing has continued.

In 2006, Beyoncé famously followed a detox diet that involved drinking a tonic made with lemon juice, maple syrup and cayenne pepper, and juice cleanses are still touted as a way to rid yourself of toxins – and a few extra pounds – today.

Now, experts say detox diets are not a good way to lose weight, and could even be dangerous – but what about those toxins?

Does today’s diet, packed with ultra-processed foods, mean that we should still be wary of toxins building up in our bodies? We take a look at the evidence for and against following a modern detox diet.

The rise – and rise – of detox diets

Detox diets have been around since the 1940s, but they really took off in the late 1990s. The theory was that we needed to cleanse our body of toxic waste – built up over periods of overindulgence (like Christmas) or from years of following a poor diet – and flush out environmental pollutants, such as exhaust fumes or cigarette smoke.

Detox diets vary, but can often involve:

• fasting for a few days and only drinking water or fruit juices
• cutting out major food groups like wheat and dairy
• avoiding ‘toxic’ foods, like caffeine and alcohol
• using a detox kit, with various supplements and powders to support your diet

The supposed benefits are clearer skin, stronger hair and nails, more energy, less cellulite, improved digestion and weight loss. In fact, this was the unspoken goal of any detox diet: although many were advertised to decrease bloating or sluggishness, these were really crash weight-loss diets.

But even at the time, experts were quick to debunk detox diets. A US study in 2005 concluded that detox diets are no more effective than the body’s own natural detox systems, and the British Nutrition Foundation calls them a fad diet.

As we learned more about how our bodies function, we started to understand the dangers of detox diets, too. The British Dietetic Association (BDA) says: “Fasting or severely restricting what you eat, limits your intake of calories and often important nutrients needed for health and well-being. Rapid weight loss can occur, but this is largely water and glycogen, rather than fat.”

As soon as you eat normally again, any ‘water weight’ will simply reappear. Cutting out entire food groups like wheat or dairy means essential vitamins and minerals, proteins, fatty acids and electrolytes could be missing from your diet. Rather than feeling better after a detox, you could feel pretty run-down or even ill.

Detox diets evolved over the years – the no-sugar diet, basic elimination diet or increasingly popular juice cleanses are all variations on detoxing – with the principles remaining the same: severe calorie restriction, eliminating food groups and drinking lots of fluids. More recently, a worrying new addition to detox diets has emerged: colon cleansing.

Colon cleansing can involve taking laxatives, having enemas or even undergoing colonic irrigation. Also known as colonic hydrotherapy, it involves flushing out your entire colon with lots of water to help remove any ‘stubborn toxins'. But, there’s no solid medical evidence that these work, and they could even be harmful, leading to colon damage or making existing bowel conditions worse.

Do we really need to worry about toxins?

The main aim of detox diets was always to remove toxins from your body. But, the definition of what these toxins are, where they come from and why we need to get rid of them keeps changing.

In the 90s and noughties, they were “pollutants, exhaust fumes, alcohol, smoke and pesticides [that could] contribute to the toxic buildup in our bodies." This build-up was believed to overwhelm our natural ability to eliminate waste, leaving us with bad skin, cellulite and low energy levels.

But, the major problem with detox diets is that humans are already perfectly designed to get rid of toxins.

“Your body constantly filters out, breaks down and excretes toxins and waste products like alcohol, medications, products of digestion, dead cells, chemicals from pollution and bacteria,” states the BDA. “It has numerous organs, such as the skin, gut, liver and kidneys, that continually ‘detoxify’ your body from head to toe by responding to signals to remove any waste products.”

In other words, detox diets are utterly pointless. But, new and ‘dangerous’ toxins seem to have appeared over the decades – free-radicals, artificial sweeteners, nitrates and sulphites, to name just a few – that have kept detox diets in the spotlight. As always, the solution was to eliminate certain food groups and drink plenty of water.

But, in the past few years, a genuine toxic threat to our health has emerged: ultra-processed foods.

Are we exposed to more chemicals in our food today?

Our diets contain a lot more ultra-processed foods (UPFs) than they did 30 years ago – over half the calories we eat everyday now come from UPFs. UPFs tend to be industrially produced, and contain manufactured ingredients you wouldn’t find in a home kitchen, such as emulsifiers, stabilisers and artificial colours or flavourings.

Oven-ready meals, fizzy drinks, shop-bought cakes, biscuits and breakfast cereals are all UPFs. But, sliced supermarket bread, flavoured yogurts and vegan ‘meat’ products are also UPFs, due to the amounts of additives or processing they go through. The general rule, according to Dr Chris van Tulleken, author of Ultra-Processed People, is that if it comes wrapped in plastic, it’s probably an UPF.

There’s a growing amount of evidence to show that UPFs are bad for our well-being. Studies found they can lead to weight gain and poor cognitive function, while a major scientific review in 2024 concluded UPFs were directly linked to over 30 “harmful effects to health”, including heart disease, cancer, type-2 diabetes and depression.

It’s not yet clear whether these effects are caused by the specific ingredients in UPFs or the large amounts of fat, sugar and calories they also contain. What is clear is that we are consuming a lot more chemicals in our food than we did in the 1990s.

Do we need an updated detox diet?

If we are now putting more toxins in our body, do we need a modern-day detox diet to get rid of them? Before you start mixing together maple syrup and lemon juice, there are some simple (and far less dramatic) ways to eliminate them.

First, cut down or cut out the amount of UPFs in your diet and replace them with healthier or home-cooked versions. This both reduces your exposure to manufactured ingredients and thigh levels of fat, sugar and salt. Putting fewer ‘toxins’ in your body will always be better than trying to remove them.

Second, support your body’s natural detox systems so they can do their job – reduce the amount of alcohol and caffeine you drink to help your liver work efficiently, eat a well-balanced diet, drink enough water, get enough sleep and exercise regularly. It may not be as Instagrammable as green smoothies, but it is much more realistic.

Finally, think about why you might be tempted to go on a detox diet: do you want to lose weight, feel more energetic or tackle issues like poor skin? See your GP to discuss your concerns and get the help you really need.

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