Sensory aversion can lead to dietary restrictions or avoidant restrictive intake disorder (ARFID), and is often linked to neurodivergence, says expert Lisa Smith. Hatty Willmoth writes.

Most people avoid some foods. It’s not uncommon to turn a nose up at squidgy mushrooms, baulk at the idea of smelly smoked fish, or pick out coriander leaves to discard at the side of a plate.

But for those with food-related sensory issues, it’s not a case of fussiness, but intense disgust at certain foods and fear at the prospect of eating them.

In some cases, this can develop into an eating disorder called avoidant restrictive food intake disorder (ARFID), where an individual avoids the vast majority of foods.

ARFID is characterised by sensory aversion to the textures, tastes, smells and appearances of some foods, as well as a fear of choking, vomiting, or other consequences of eating, a fear of new foods, and a lack of interest in eating.

It’s a little-known eating disorder, but that might be changing; the Guardian reported in February 2024 that calls to the UK’s leading eating disorder charity, Beat, have risen sevenfold in the last five years.

And this may be – at least partially – because of the links between sensory issues, ARFID, and neurodivergence.

Links between neurodivergence and ARFID

Lisa Smith is a functional nutritionist who specialises in neurodiversity, eating disorders and disordered eating. She’s also a co-founder of NEDDE (neurodiversity, eating disorders and disordered eating), which trains nutrition and mental health professionals to better support neurodivergent clients.

'Neurodivergent' can be used to describe individuals whose brains function in a way that isn't typical. It's a nonmedical term without a strict definition, but it commonly refers to people with autism spectrum disorder (ASD) or attention deficit hyperactivity disorder (ADHD), and sometimes refers to those with other conditions such as Tourette syndrome, dyslexia, learning disabilities, certain mental health conditions, or something else.

Smith says that ARFID often “goes hand in hand with some form of neurodivergence” and that the two are closely linked.

For instance, she says, “a lot of autistic people have issues with oral motor: chewing”.

“[They might have a] swallowing issue as a follow-on from that,” she adds, “especially if they’ve had any experience of choking because they haven’t chewed something properly.”

This may prompt individuals to avoid foods which require more chewing or which they consider a choking hazard - and it's a possible symptom of ARFID.

Hypersensitivity, sensory overload and autism

Hypersensitivity is another possible link between ARFID and neurodivergence. Common in people on the autistic spectrum, hypersensitivity is when the senses are heightened to the extent that sensory input can feel overwhelming or uncomfortable – including the texture, taste, smell and appearance of food.

“Food’s a multi-sensory assault on the body,” says Smith. In a neurotypical world which a neurodivergent individual may find “demanding”, “challenging” and “anxiety-inducing”, she explains, many feel the need to avoid foods which might contribute towards sensory overload.

As such, neurodivergent individuals may develop a restrictive diet, or even ARFID, and this can come with health consequences.

Restrictive diets can lead to nutritional deficiencies, which Smith says can “starve the brain” of vital nutrients and thereby “magnify neurodivergent behaviour”.

Plus, people with ARFID and some form of neurodivergence tend to gravitate towards foods which are nutritionally poor.

Smith says: “If you have something that offers you predictability, consistency, and that doesn’t challenge you in any way, obviously you’re going to be drawn to that.

“Unfortunately, the most predictable foods are [ultra-processed foods and fast food]. If you think of MacDonald’s, they taste the same wherever you are in the world, so you don’t have to get any more overwhelmed.”

Hyperfixation cycles and ADHD

Beyond hypersensitivities, many neurodivergent individuals develop hyperfixations, especially if they have ADHD.

From the outside, a hyperfixation may seem like an obsession; in food terms, a person may choose to eat the same meal over and over again.

It’s comforting, says Smith, but hyperfixation foods are often low in micronutrients, heavily processed, and high in sugar, refined oils and salt.

“Quite often with ADHD, that’s what it is,” she says. “Because [the foods have] that sugar, fat, salt in them, it's going to actually interact with [dopamine] receptors.

“A neurotypical might go, ‘ooh, I really like that’. For an ADHD person with a dopamine deprived brain, the reward that they will get from that food will be greater.”

But hyperfixations can end in an instant. A food will lose its feel-good factor, says Smith, and then a neurodivergent person may wish to avoid it completely – which can become another road to restriction.

Add foods, don't take them away

But Smith says that the number one rule for helping neurodivergent individuals with restrictive diets or ARFID, is that they should be allowed to continue eating the foods they already like.

“Don’t ever take away those ‘safe’ foods,” she says, “especially within ARFID. It’s always about what you’re putting in, not taking out.

“Even if they’re only eating cornflakes, they’re eating.” This is absolutely crucial when working with children, she says, but with neurodivergent adults too, it is not usually worth trying to enforce a perfectly balanced diet.

“What you need to do is work with that individual,” says Smith. “You have to find out, what are the acceptable tastes, textures, smells, and then look at what they are eating and say: ‘How can we make what they are eating just a bit more nutritious?’.

“I have one client where everything needed to be crunchy. Well, great! Let’s dehydrate food. Let’s make it crunchy.

“It’s working with them; changing the environment to the individual, not trying to force the individual into the environment.”

How to tackle ARFID with food chaining

Once it’s clear what that person likes and dislikes, change can begin to happen – but it must be slow.

Smith says a technique called ‘food chaining’ can be quite effective, to diversify the diet with tiny steps that don’t feel too overwhelming.

For example, she explains, a neurodivergent individual may eat fast food beef burgers. So, the first change might be buying one of those burgers but swapping the bap.

Once they’re used to that, the burger could be swapped with a supermarket option; then made at home; then eaten without the bap.

Smith says: “It’s about slow changes, and you always try to keep things looking the same or tasting the same, [and just] make it more nutritious.

“Because if you’ve got it looking the same, at least then that’s one sense that somebody hasn’t got to work with.”

Similarly, if someone eats pasta with a tomato-based sauce and cheese on top, Smith might switch 10% of their pasta with a higher protein pea-based pasta in the same shape. Over time, that percentage can be gradually increased, increasing the dish’s protein content.

Smith says: “What you’re doing is slowly changing the nutritional value of that meal. It needs to be done slowly. If you do it straightaway, it’s going to be too much of a challenge…

“When you’re looking at especially autism and ARFID, just the thought of the change could be anxiety-inducing.”

Don't be afraid of unconventional combinations

Working with neurodivergent individuals with restrictive eating challenges may mean embracing some bizarre food combinations – throwing the ‘food rules’ out the door, as Smith says.

“I’ve had a client that, everything had to be in tomato ketchup. Well, fine. That’s absolutely fine. Eating broccoli dipped in tomato ketchup is better than not eating broccoli at all.

“I have people that have banana and marmite sandwiches. That’s absolutely fine. If the marmite covers up the taste – or whatever it is – then, fine. Have that.

“You can use the marmite there – or whatever their key thing – to smother other foods in. And then you can start to slowly reduce the marmite.”

But hiding foods is something neurodivergent people must do themselves; well-meaning parents, relatives or friends should not try to trick them into eating foods they prefer to avoid.

Smith says: “That can cause a problem, because the individual finds out and then the trust has gone… If they thought [their food] was one thing, and … realised it was another, that would be a challenge they weren’t ready for.”

Neurodivergence is just different wiring

The final nugget of wisdom Smith advises is to focus on improving health, not fixing neurodivergence itself.

“If you are neurodivergent, you are neurodivergent. You’re not broken. You don’t need mending. It’s just different wiring," she says.

“I still get clients that come to me and say: ‘I want you to cure my son’s autism.’ And I say: ‘Well, your son is autistic. That isn’t going to change. What we can do is help by installing coping mechanisms, helping him to understand, looking at the environment.’

“A neurodivergent interacts with the world in a different way to a neurotypical, but they live in a neurotypical world.”

Neurodivergence isn't new - but awareness is

As for the increase in calls to eating disorder charity Beat for ARFID, Smith believes this could be down to increasing awareness around neurodivergence – particularly for people on the autistic spectrum and with ADHD.

“We’re looking at neurodivergence differently,” she says. “Previously, it was always thought to be teenage boys, whether it was autism or ADHD.

“Before, all the studies were done on young adolescent males, and if you didn’t fit that criteria, you didn’t get the diagnosis.

“Everybody saw the boy that was charging around the classroom being disruptive, but what they didn’t see was the girl in the corner colouring away in her own little world, because she was quiet.

“Some people say: ‘It’s a new thing. Everyone’s got neurodivergence. It’s a new trend.’ Actually, it isn’t … we’re measuring it against a different thing…”

Neurodivergent clients? A message to practitioners

Smith also wants to encourage nutritional therapists and other healthcare practitioners to embrace working with neurodivergent clients.

“I often speak to nutrition professionals that say they don’t work with eating disorders, or they don’t work with neurodivergent individuals,” she says.

“My comment would be, yes, you do, but you’re not asking the right questions.” She says that neurodivergent people often try to ‘mask’ – “like acting” – to appear neurotypical.

“The problem is, if they are given a neurotypical set of recommendations, we’re almost setting people up for failure, which is the last thing that a neurodivergent person needs, because they live in this neurotypical world that isn’t necessarily friendly to them.”

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