The Zoe App Changed How I Think About Fats

I had seen the Instagram videos showing people popping the Zoe app’s glucose monitor onto their upper arms and promising that “it doesn’t hurt”. Reader, I won’t lie to you. When I put mine on, it did hurt a little bit. Not at first, but afterwards for half a day. Possibly, I’ll admit, because I slept on my arm.  

But, as people far wiser than me perennially say, “No pain, no gain”. And, for that minor pain, I gained a lot from my relationship with Zoe. She taught me a lot. 

Zoe first became known for symptom tracking at the height of the COVID-19 pandemic, but has since been turned into a personalised nutrition app which is also currently the world’s largest nutrition science study.

Founder Dr Tim Spector and his creation are now at the centre of talk about personalised nutrition which, as time goes by, is becoming increasingly loud. It is, I keep reading, “the future of health”. Now, having tried it, I think that’s a fair assessment.

This has nothing to do with dieting or calorie counting and is instead based on a simple premise: There is no one-size-fits-all approach to what we should be eating. Rather, evidence suggests that our unique biology means that we respond to the same foods differently.

Some things are universally true — a mixed and varied diet based around fresh fruit and vegetables with oily fish and healthy fats is desirable for the majority of people. However, a Zoe study conducted by scientists at King’s College London found that the difference between how individuals – even identical twins – experience dietary inflammation can be tenfold. 

There are several reasons for this. Everyone has different microbes in their gut, blood sugar, fat and insulin levels. Everyone exercises differently. Everyone’s sleep differs too. Everyone’s genetics are different. 

Jacket potatoes, for instance, might exhaust you. But they make me feel like I could run a marathon. Pasta might feel comforting and filling for you. It sends me into a complete energy spin. A friend of mine, who is similar in stature and age, coincidentally was doing Zoe at the same time as me. Interestingly, pasta did not cause her blood glucose to rise as fast or sharply as mine. But potatoes, which leave me feeling ready to take on the world, made her crash. 

Zoe, via the glucose monitor placed in your arm, tracks your blood sugar response to food and drink for two weeks — as long as you are honest with her, of course, and accurately log everything you consume, which I did. 

Next up, courtesy of a stool test (yes, you send them some of your poo. Not as gross as I feared), it tells you about your gut microbiome and the diversity of the species and ratio of good to bad bugs living in there. You also provide a tiny sample of your blood (actually fine and not painful), which they analyse to tell you about your blood fat responses. Combined, these at-home tests give you information about how your body handles fats and sugars (carbohydrates break down into glucose after you eat them) and, ultimately, a picture of your overall health. 

For my part, there was one very specific thing I wanted to know from Zoe: Why am I always so tired? Could my diet be both the problem and the solution?

The short answer, it turned out, was yes. But not in the ways I expected. 

Once I had completed my Zoe testing, I spoke with Dr Federica Amati, head nutritionist at Zoe and author of two books about women and nutrition: Every Body Should Know This and Recipes for a Better Menopause.

Though she graciously tried to conceal it, I registered the shock on Dr Amati’s face when I told her how I had been feeling and what I had been doing pre-Zoe. Namely that was avoiding fats and reducing my calorie intake on the advice of a personal trainer I had been working with to try and stay in a deficit. 

“You’re probably not eating enough food,” Dr Amati said right off the bat when I told her I was tired all the time during our first call. 

She was right. During my two-week Zoe testing period, I ate more than I had in months. And, reader, I had more energy, was happier and less bloated than I had been in months. 

The results shown to me by Zoe’s glucose monitor were stark, clear and challenged the narrative I absorbed by osmosis as a young woman growing up in the “Special K diet” 2000s era that fat was bad. Good fats — like butter, olive oil and yoghurt – which I had dutifully avoided as a child of noughties diet culture, are actually very, very good for me. 

The glucose monitor showed that consuming healthy fats such as avocados, butter, Greek yoghurt and cheese kept my blood sugar more stable than so-called “healthy low-fat alternatives” or the ill-advised protein shakes I’d been advised to replace the odd meal with. Eating these things also — wait for it — made me feel energised and fuller for longer. 

My doctor thinks I have endometriosis and I’m waiting for more tests. After speaking with Dr Amati, I learned that avoiding healthy fats could also be part of the reason why my condition had become more painful. 

Endometriosis is a complex condition that, Amati explained to me “includes inflammatory response and the immune system.” As a result, she notes that the current evidence suggests that “a diet rich in fibre from a variety of plants and healthy fats can help support a healthy immune system and manage excess inflammation.”

“With endometriosis, it’s really important to have a good oestrogen/progesterone balance,” Amati explained on our call. “It’s important to reduce bloating and swelling and pain.”

“So,” she continued, “if you were eating very low fat and very low energy, it’s likely to have impacted your hormone levels.”

Had I known this, I would have approached my diet very, very differently. 

On some level, did I know all of the above? Yes. But knowing something logically did not necessarily equate to me being able to believe it because diet culture has made so many of us, me included, scared of fats and calories. 

Now, you might be laughing at me. You might also be surprised that I — someone who has written about diet culture and the pressures women face — also succumbed to those pressures. There’s an important point to be made by the fact that I did: When it comes to diet, cultural conditioning is as pervasive as it is powerful. 

Arguably, I didn’t need Zoe to tell me that healthy fats were good for me but using the app and the glucose monitor did override some of the beliefs I held and, crucially, didn’t even realise I held so strongly. I was able to see my body respond to food in real time. I always knew pasta didn’t work for me, but seeing the glucose dip in my blood glucose on the glucose monitor’s app confirmed something I’d long felt. I could connect what I saw on the screen with the low energy slumps I was experiencing from low-fat foods and protein bars and with the more stable energy I felt when I ate the foods I had been avoiding. It helped to rewire my brain. 

My other results were reassuring. As Dr Amati talked me through them, I had a creeping feeling that I had been doing more damage than good to my body, which was healthier than I realised. My blood sugar control was in the “excellent” category, and so was my blood fat control and microbiome score. There was nothing wrong with me — I am fit and healthy and I had made myself feel drained because I hadn’t been eating enough food. 

The current vogue for obsessing over glucose spikes brings its problems. Not everyone has access to nutritionists like Dr Amati and there’s a lot of misinformation on social media. A spike is not necessarily bad in and of itself: As multiple studies (conducted by the Zoe team because they now have access to so much data) have shown, spikes are your body’s normal response to food. But other studies — like this one from Stanford — show that it’s never a bad idea to pay attention to what you eat and how it makes you feel, even if you are not predisposed to conditions like diabetes. Stanford researchers make the point that they found that perfectly healthy people’s blood glucose spiked after a bowl of cornflakes and milk and drew the conclusion that it’s “probably not such a great thing for everyone to eat.” This sort of information is now being widely disseminated thanks to Zoe, and apps like Lingo that are springing up in its wake. 

There are also now influencers with hundreds of thousands of followers who have dedicated their pages to trying to hack glucose, encouraging people to eat a spoonful of yoghurt before their breakfast and avoid certain foods in favour of others. In the wrong hands, this information can encourage obsessive monitoring and restrictive behaviour. It also implies there’s a one-size-fits-all approach to nutrition which isn’t true. 

Given that hospital admissions for people with eating disorders in England have risen 84% in the past five years and that NHS support for sufferers seems to be in short supply, it’s really important that we are all mindful of how we talk about tracking what we put into our bodies. 

For me, though, Zoe presented a refreshing foil to the pernicious diet culture I grew up around which was spawned by Slim Fast, Weight Watchers and photos shaming celebrities for having “orange peel thighs”. That’s not a thing, by the way. I can imagine it might also help someone younger than me who has been exposed to Instagram influencers talking about calorie restriction, “leggings legs” on TikTok or Kim Kardashian’s Met Gala “diet”.

And I don’t say this lightly. Zoe helped me to reject some advice that had been making me feel very unwell because I could see my body thanking me for making nutritious choices whenever I checked the app. I was less keen on seeing Zoe’s response to white wine but you can’t have it all.  

“I really wish people would stop spouting nonsense about calories being the best way to think about food ,” she said. “If you’re not nourishing yourself with nutrient-dense food, your body will think there is scarcity and react to preserve energy because we evolved to survive famine and your metabolism will slow everything down. If your body is not getting enough fuel, it will preserve whatever it can.”

Conversations about weight and weight loss aren’t going anywhere. But that’s not what the majority of young women are subjected to and the likes of Dr Amati can provide vital reassurance that eating healthy fats and substantial portions of fruit, vegetables and fibre can help you find balance in a healthy body. 

Dr Amati concludes that the benefits of addressing diet when you are young are wide ranging. 

“Women in their 20s and 30s are often in their fertility window and being properly nourished at this time is crucial for the woman and for her potential children,” she explains. “Foods that are rich in iron to compensate for blood loss with menstruation, high in a variety of diverse foods to include all of the important micronutrients, fibre and amino acids is really important.”

Dr Amati cautions that your 20s and 30s are “often the time when women deprive themselves of a variety of foods” which “can hinder their potential to lay the foundations for a strong and resilient body later in life.”

You might not be thinking about getting old yet but Dr Amati is clear: “Making sure you eat enough high-quality food to support your immune system and your hormones is a powerful tool, and building a good skeletal muscle mass [in your 20s and 30s] is vital for healthy ageing”.

At a moment in time when fewer people in Britain can adequately access public healthcare due to increasing, and sometimes deadly, waiting times, it tracks that those with means — Zoe testing costs £299.99 and membership to a recommended 12-month plan after that is £24.99 a month — are prepared to spend money in a bid to feel a sense of control over their health. 

“Prevention is better than cure” was a founding principle of the NHS when it was founded in the 1940s but sadly, it is now so overburdened and under-resourced that it is fast becoming a patchy triage service. 

Personalised advice and medical care is definitely the future. But right now it’s only available to those who can afford it. My only wish is that Britain’s National Health Service was properly funded so that everyone — not just young professional friends of mine or journalists like me — had access to Zoe and the brains of people like Dr Amati when needed so that, like me, they could be given the information to make better choices.