That melt-in-the-mouth biscuit, puffy potato snack or fluffy white bread all have one thing in common – a moreish, soft texture.
Does it matter? Well, yes, because research into ultra-processed foods (UPFs), which are often blamed for weight gain and poor health, suggests that one of the main problems may not just be their lack of fibre and lower nutrients, but their soft texture.
UPFs are, broadly speaking, highly processed foods containing additives and ingredients that you wouldn’t find in a home kitchen. They are typically high in calories, salt, sugar and fat.
Whenever we eat anything, the food stretches the stomach until it releases fullness hormones to tell the brain we’ve had enough. But these signals take time to travel through the body.
The thinking is that because UPFs are so easy to chew and quick to eat, we end up eating more of them before our body’s fullness signals have time to catch up – essentially, the brain doesn’t get the message in time.
That’s why the quicker you can down food the more likely you are to carry on going and overeat. This is not a problem occasionally, but if it happens often it can mean you’re eating more calories than your body needs.
It was a key study, published in the journal Cell Metabolism in 2019, that first identified how much UPFs encourage overeating. It found that, on average, people ate 500 more calories per day when on a UPF diet compared with an unprocessed one.
For the study, 20 participants were allocated either an ultra-processed or an unprocessed diet that were matched for calories, sugar, fat and fibre, and allowed to eat as little or as much of them as they wanted.
Dr Emily Leeming is a microbiome scientist, registered dietician and chef
Those on a UPF diet gained nearly a kilogram in just two weeks, while those on the unprocessed one lost the same amount.
And it wasn’t because UPFs tasted better. Participants didn’t rate them as more enjoyable, but they did eat them twice as fast.
Yet it isn’t just UPFs that have a softer texture – soft, minimally processed foods such as apple puree are also eaten much faster than when in their raw form as a whole apple.
A 2022 study in The American Journal of Clinical Nutrition found that softer foods, whether ultra-processed or not, make us eat more simply because they’re quicker to chew and swallow.
This was echoed in another study in 2023, published in the European Journal of Nutrition, which showed that how hard or soft food is affects how much we eat way more than whether it’s processed or not.
In the study, participants ate 33 per cent more and 85 per cent faster when their meals were soft – ultra-processed or unprocessed made no difference.
It’s a similar story with drinks. A 2008 study in the International Journal of Obesity found people drank a lot more thin chocolate milk compared to thicker, custard-like versions – about 30 per cent more, which added up to an extra 243 calories.
It turns out that thicker drinks simply take longer to get down, helping us feel full faster and so needing less of it overall.
Soft foods are less filling and easier to chew, so it takes longer to set off the brain’s fullness signals than bulkier and non-processed foods
One reason the feedback mechanism to the brain is slower with UPFs is that softer foods are less filling – they take up less space in the stomach.
Bulkier foods stretch it, signalling you’ve had enough.
This doesn’t mean you should avoid all soft foods.
Many of them, such as Greek yogurt and mashed sweet potato, are full of nutrients and a great part of a healthy diet.
Soft textures can also be a life-saver for older people, making it easier for them to get enough nutrition when chewing becomes harder and with a lower risk of choking.
But if you’re reaching for something that’s higher in calories and lower in nutrients, it might help to think about texture.
And it’s not only the texture – or lack of it – that might make us overeat, there are other pitfalls to avoid too. Here’s how.
Pay attention to what you’re eating
Eating while distracted can make us eat more without realising it.
A 2013 review and meta-analysis published in The American Journal of Clinical Nutrition found that people who ate while distracted ate about 10 per cent more at the time and about 25 per cent more at their next meal because they hadn’t taken the time to appreciate how full they were.
On the flip side, paying attention to what you’re eating – such as noticing the taste, texture, and smell – helped people eat about 10 per cent less at later meals.
This might be because remembering what you’ve eaten can help your body’s fullness signals do their job.
To eat more mindfully, try putting away screens, taking smaller bites and focusing on the flavours and textures of each mouthful.
This way, you’re giving your body time to realise when it’s had enough.
Use smaller cutlery at home but big when out
Using smaller cutlery can help you eat less without noticing, but it depends on where you are.
A 2018 study in the British Journal of Nutrition found that using a small spoon made people take smaller bites and eat more slowly, which led them to eat about 8 per cent less overall.
This is because smaller bites give the body more time to signal that it is full.
Interestingly, other research suggests that the setting – where you are eating – matters.
At home, using a smaller fork or spoon might help you eat less, but in a busy restaurant a bigger fork could actually help you feel satisfied sooner and stop you from over-eating, according to a 2012 study published in the Journal of Consumer Research.
The researchers found that in a restaurant, people are more motivated to eat. But with a smaller fork they didn’t feel like they were making progress, so they ended up eating more.
So try using a smaller fork or spoon when you’re eating at home to help with portion control, but go for bigger cutlery when dining out to avoid eating too much too quickly.
And yes, chew your food more
‘Chew your food’ properly and don’t rush is something parents typically say to their children. But it can also apply to adults, as chewing food more can help you eat less.
A 2014 study published in the Journal of the Academy of Nutrition and Dietetics found that when people chewed each bite 150 per cent to 200 per cent more than usual – around 42 to 56 chews per mouthful – they ate up to 14 per cent less food.
Chewing slower also makes meals last longer, giving the body time to release hormones that signal fullness, without making people feel hungrier afterwards.
To try this yourself, start by counting your chews for a few bites at each meal and aim to double them.
This simple change might help you feel full sooner and naturally eat less.
