Is it really because they're 'ultra-processed'?
Food texture explains a large part of why we easily overeat ultra-processed foods
A lot of the concern around ultra-processed foods is down to how much we’re eating of them.
The first randomised controlled trial on ultra processed foods found that participants ate 500 calories more a day on an ultra-processed food diet, than a minimally processed (aka whole foods) diet.
500 calories more a day - that’s the equivalent of a big mac or 1.2kg of carrots.
Why might this be?
Is it that they taste good?
Or that they don’t fill you up that much?
Likely there’s a bunch of different reasons. There (usually) always is!
There’s one key factor that’s been missing from the conversation though.
And it can explain a large part of why this happens - rather than because a food is ‘ultra-processed’.
Is this why we eat more ultra-processed foods?
One surprising reason seems to be that many ultra-processed foods have a soft texture.
And it seems to be that the texture of a food matters, whether it’s ultra-processed or not.
Two studies in particular have explored how the texture of a food can lead to us eating more or less of it.
Both studies compared how much was eaten if foods had a minimally processed soft texture, minimally processed hard texture, ultra processed soft texture and ultra-processed hard texture.
Soft minimally processed e.g. well cooked veggies, yoghurt, banana
Hard minimally processed e.g. brown rice, raw salad, apple
Soft UPF e.g. instant mash, canned mango, flavoured yoghurt drink
Hard UPF e.g. dried mango, potato waffle fries, veggie crisps
Clearly the minimally processed meals and diets were more nutrient dense. But here’s where it gets interesting.
Both studies found that participants ate the softer texture more quickly and ate more of it, than the hard texture - and that the ‘processing’ category didn’t matter so much, or at all.
In the first study, the participants ate 33% more calories from both soft food diets, and ate 85% quicker, than the hard textured diets - the level of food processing had no effect at all on the results.
The second study found that the processing level did matter for energy intake but not total food intake - but still - both the hard minimally processed meal and the hard ultra-processed meal were eaten slower and they ate less calories than the soft textured equivalents.
If you look just at the ultra-processed meals - the hard ultra-processed meal was eaten 2 times slower, and they ate 25% less calories, than from the soft ultra-processed meal.
Why might this be?
When you eat quickly you spend less time in ‘eating mode’ where there’s a continuous feedback loop relaying hunger and fullness signals between your gut and your brain.
Less texture to a food is also less filling - the more bulk to a food stretches the muscles of your gut and can signal you’re full and don’t need to eat any more.
So where does this leave us?
Many of the foods that fall into the ultra-processed food categories are those that we already know are less nutrient dense and tend to be higher in energy, sugar, salt and saturated fats like sugary fizzy drinks, sweets and pastries - and have softer textures.
We know that these foods are ok if we’re eating them occasionally - they taste great and food is so much more than nutrients alone. It’s when these foods make up most of what we eat that they are linked to greater risk of poor health and diet-related diseases.
Many other foods however fall into the ‘ultra-processed’ food category - and seem to be protective of our health. Ultra-processed bread and ultra-processed yoghurt are related to lower, not higher, odds of disease.
Is the ‘ultra-processed’ classification just creating more unnecessary confusion around nutrition? Particularly when not everyone can afford sourdough and the like.
The collective hours spent pondering the ingredient labels between this jar of pesto or that organic additive-free one that costs £1.50 more - could in truth be spent (time, effort and money) on some extra fruit, veg or whole grains.
Far better for your health and your headspace.
That’s it for now! If you have a thought percolating from this, I’d love to hear it - drop me a comment below.
Chat soon, Emily xx
P.S. Did you know my first book Genius Gut will be released in July? I share the latest science on your gut-brain connection, how your gut microbiome influence your mood and emotions and most importantly - 10 simple steps to feel happier, more balanced and have more energy.
SO many thoughts percolating .. found this fascinating. Thank you !