Madonna. Kylie… Zoe? No, she’s not an A-list celebrity, but the name of an app whose users are recognisable by the little yellow sticker on the top of their arms. The brainchild of Professor Tim Spector, this app was first developed to monitor Covid symptoms, then became a way to offer personalised nutrition plans.
Since it was founded two years ago, 130,000 people have used it, paying £199 for a personalised plan, with thousands on the waiting list. Indeed, jealousy was the main reaction when I told people I was “doing Zoe”. What this meant in practice was that for the next few weeks, I would wear a blood glucose monitor (the yellow sticker secures it) which would test what happens to my body after I eat, and transmit that information to an app to help me assess how my body responds to different foods.
A Zoe-sponsored study conducted by scientists at King’s College London found that people’s responses to dietary inflammation can vary up to tenfold. I’d also test blood fats and digestion speed. During this process, the idea was that I’d learn how to avoid the big peaks and dips in blood sugar that follow some meals, how to keep my blood fat levels in check, and how to support my gut microbiome.
They would then give me my results, and a personalised nutrition plan which would “change how I eat forever”. This plan would include a list of the foods that are best for my body and my gut.
Why do I need it? Generally, I think I eat quite well, with a varied diet, plant-heavy with plenty of legumes and grains, little meat, fish once a week, and the only processed food I eat is the occasional ice-cream, snatched bite of fish finger from a child’s plate, maybe a Sunday night pizza takeaway.
However… when I do eat butter, it’s half a centimetre thick. I’m very keen on mayonnaise. When I drink, it’s quite a lot. I put far too much salt and spicy condiments on my food. And I’ve always had a sluggish digestion. I was hoping Zoe could help me with this. I’ve also always been curious about my gut health, and I wanted my diet to be held to account for a little while. I was keen to test my blood fats, too, and learn a bit more about what’s going on inside my body, particularly because of the butter issue.
Here’s what happened when I tried.
Day 1
I begin the Zoe testing process by applying a blood sugar sensor (a tiny needle on the back of a white disc which will stay in my arm for 10 days or so — it’s less painful than a flu jab). I then have to collect and send off a stool sample — always a joy.
Day 2
An overnight fast, followed by the outrageously sweet “breakfast cookie” they provide. Then, a four-hour fast and a blue lunch cookie. It’s blue so that the dye will travel through your system, meaning you can track your digestive speed by noting when your stool turns blue — yes, really. Then, it ‘s an at-home blood test, to measure my blood fat responses to the cookies. What you hope is that your body is efficient at clearing fat from your blood after a meal. It’s partly genetics, and partly the type of fat you eat that affects this — healthy fats such as avocado and nuts are easier to clear than unhealthy ones. Responses to food are of course normal. But if blood fat levels stay elevated for a long time, and blood sugar levels are repeatedly subjected to high peaks and dips, that can become harmful, the app tells me, with potentially dramatic long-term results. They raise inflammation, which can “lead to weight gain and chronic diseases such as diabetes and heart disease”.
It is also related to the gut. The scientists behind Zoe have conducted studies which identified “good” gut bacteria linked to lower levels of blood sugar, blood fat, inflammation, and less body fat; and that certain “bad” bacteria are linked to higher levels.
Day 3
For the next three days I log everything I eat, while taking part in challenges set by the app, and some of my own, to show myself (and the team who assess all my results) how my blood sugar responds to different foods in combination with each other and exercise. Challenge one: what do a few glasses of rosé on an empty stomach do to my blood sugar? Massive spike! What about if I have a fishcake and some broccoli first, and then the wine? Much, much lower. Result.
Day 4
What makes it spike more – a bowl of chocolate ice-cream, or a fish finger sandwich with mayonnaise on white bread? Drum roll… It’s the fish finger sandwich — by a long way.
Day 5
Why is there a glucose spike at 7.50am when I haven’t eaten anything yet? I did have a herbal (lemon and ginger) tea at 7.15am, could that really do it? Surely it’s just water. Later in the morning I have a slice of white sourdough and two boiled eggs and a milky coffee — get quite a big glucose spike with that meal. Later in the day I have a BLT on wholemeal bread and that raises my blood sugar substantially. I know sliced bread isn’t great, but that still surprises me.
Day 6
After reading a “Zoe lesson” on the app, I test what happened to my blood sugar levels if I go for a walk straight after eating — it certainly helps to “flatten the curve”.
Day 7
A sweet potato and broccoli salad followed by a beer, and half a bottle of red wine at the theatre. My blood sugar readings stay almost perfectly flat.
Day 8
A bowl of Dorset Cereal Gloriously Nutty muesli. No added sugar, but lots of dried fruit. This is the only meal in the entire process which pushes me into the “red” limit of the blood sugar spikes.
Day 9
Different food sequences (eating in different orders) or pairings (what you eat the food with), will, or should, affect it. Mango on its own — glucose spike. Cheese before mango — much flatter. This is called “fat stacking” and is one of the cornerstones of the Zoe way of eating.
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Day 10
Lunch is a noodle, chicken and veg salad — but I eat the noodles first, then the chicken 10 minutes later. This gives me a big spike.
Day 11
This time I have the chicken, followed by noodles 10 minutes later. Yes, it gives a much smaller spike. But oh, does it take the joy out of eating. And it is this focus on blood sugar spikes, which is where much of the criticism of the Zoe app comes in. It’s claimed that the popularity of the app has meant that people focus too much on trying to control blood sugar spikes in order to achieve better health or weight loss, at the expense of other health markers.
Day 12
I have a salmon and egg baguette sandwich from Pret. I hope that the protein and fat-heavy filling will counteract the white bread sugar spike I’m expecting. It does not. I have a huge spike followed by a big dip, into the “red zone”. Even chocolate affected me less.
I continue like this for nearly two weeks, following the challenges, and finding inventive ways to add extra ingredients to my meals at the app’s suggestion, to “flatten the curve”. They say that the advice is tailored to the needs of my own gut and body.
So, am I balancing my blood sugar curve? Yes. Keeping blood fat levels in check? Yes. Nourishing gut microbes? Yes. But after four weeks, I realise that my meals are just getting bigger and bigger to hit the targets and recommended portion sizes, and the fats to flatten my blood sugar… and as a result I’ve put on weight — an extra 2.5kg. That’s more than a quarter of a stone.
Trying to get a “good” response made me competitive with myself. They wanted me to eat 30 different plant-based ingredients a week — well, I wanted to eat 40. They wanted me to keep my spikes as flat as possible — that became an obsession. I was giddy with excitement when I got my blood fat results back, a score of 95 out of 100, “excellent”. My blood sugar control was measured as 77, also “excellent”. I was cross with myself that my gut health didn’t score as highly (73/100) and my pre-Zoe diet was rated as 68/100 — not quite as good as I thought.
For the next month I continue logging every meal, trying to hit the targets. But I stop inputting alcohol because I don’t like how it affects my stats. Once I realise I’m lying to the app, I realise it is time to stop. I learn that it played to the worst parts of my personality — competitive, addictive. I had become obsessed with trying to make the app tell me that I was doing well.
So, now that I’ve quit the app, what has changed? I am instantly more relaxed. And then go on a fairly crazed weekend of booze, cakes, white carbs and sugary cereal. I am thrilled not to have to log any of it. Then, come Monday, I realise that I hated behaving like that, feel bloated and sluggish and rubbish, and head straight for a bowl of porridge with cashew nut butter, mixed nuts and seeds (six different kinds), a handful of berries, and a black coffee. All very Zoe. Since I’ve stopped using it, I’ve found a way to follow some of the rules and advice I learnt without being beholden to it.
I am, however, still regularly using the recipes on the Zoe Instagram account (they’re not just healthy, they’re delicious) — I’m just not adding peanut butter or cheese to every meal. And thank goodness, the extra 2.5kg has gone.
