IT has been touted as the most scientific diet ever – pioneered by world-renowned scientists and based on data from the world’s largest nutrition and health study.
The promises are bold: lose half a stone in 12 weeks, feel “80% more energized” and avoid heart disease – and all without counting a single calorie.
Before getting started, dieters are given a battery of DIY tests to perform at home.
These aim to measure exactly how each individual reacts to sugar and fat, as well as the quality of the essential “friendly” bacteria in our intestines, which govern feelings of hunger and fullness, and the quality of our digestion of food, among other things. The results allow experts to assign each food a score indicating how healthy it is for your personal genetic makeup. This, they say, allows users to make smarter meal choices. But nothing is on the table.
The diet was devised by Professor Tim Spector, perhaps best known as the founder of the ZOE Covid Symptom Tracker app, which offered crucial insight into the changing nature of the virus.
Before being sidetracked by the pandemic, Professor Spector’s main area of research was personalized nutrition, the theory that our weight is, to some degree, determined by how our bodies process certain foods – and this varies from person to person.
This explains why, according to proponents, some people seem to pile on the pounds after a few bowls of pasta, while others stay perfectly fit.
Professor Spector says: ‘Most mainstream diets don’t take this into account – and that’s why they fail. But eating according to your body’s physiology can reduce inflammation — which we know is linked to diabetes and heart disease — and reduce drowsiness and feelings of hunger. And the weight loss should be a pleasant surprise.
The plan, called ZOE (meaning life in Greek) costs £559 for the test kit and an annual app subscription. More than 300,000 customers worldwide have signed up since its launch in April.
So is this finally the weight loss answer we’ve all been waiting for? Users certainly seem thrilled.
Julie Holton, 57, lost a stone in seven months – and says it’s the only diet that’s ever worked to shift her post-menopausal pounds. And Paul Sculfor, 51, says he got a “burst of energy” after three months on the diet and no longer takes afternoon naps.
Others say they were ‘blown away’ by the information about their bodies and are ‘losing weight and feeling healthier’.
Still, some experts remain skeptical. They say the plan’s barrage of information triggers obsessive thoughts about eating right and an unhealthy focus on food scores.
And it must be said that the cost – £559 a year or £399.95 for four months – is a high price to pay for recommendations that are no different from those on the NHS website: eat more vegetables and less sugar and fat.
And then there are questions about whether the benefits of the microbiome — the bugs in our guts that are believed to play a role in everything from weight gain to mood enhancement — have been overstated.
So what is ZOE? When users place an order, they receive two large yellow boxes, containing a host of self-testing tools.
One of the first tasks for users is to send a stool sample to ZOE scientists for microbiome testing. Professor Spector’s team is checking the signs of 30 species of bacteria – 15 ‘good’ and 15 ‘bad’ – for appetite regulation and weight control.
This is followed by tests to measure how the body reacts to fatty and sugary foods – by eating specially formulated muffins, also in the box.
On the third day, clients swap breakfast and lunch for high-fat muffins, before taking a blood test in the evening by pricking their finger and sending it for analysis. This is designed to determine how quickly saturated fat is cleared from the bloodstream after eating – a risk marker for heart disease.
On the fourth day, users do the same with the muffins that are high in sugar rather than fat.
The body’s response is tracked by a continuous blood glucose monitor – a small circular device that is glued to the back of the upper arm and monitors blood sugar levels 24/7 by real time.
This sensor is one of ZOE’s main selling points. These devices are a well-known part of the treatment for type 1 diabetics. The disease leads to dangerously high blood sugar levels, and patients must regularly inject themselves with drugs to control it, so they need to monitor their levels closely.
But in the ZOE plan, the sensor is worn by healthy people. The goal is to track spikes and dips in blood sugar after eating certain foods. Big spikes in blood sugar followed by crashes are said to make us hungrier, while a steady release of blood sugar keeps us going longer.
A study published last year by Professor Spector’s group at King’s College London and other Harvard scientists showed that participants who had an extreme drop in blood sugar two to four hours after eating had an average of 9% hungrier than the others.
ZOE users must log everything they eat while wearing the monitor in an app – which connects to the sensor – so the algorithm can make associations between foods and blood sugar responses.
They are also encouraged to eat a variety of foods and check their blood sugar response through the app.
‘People who have irregular blood sugar may have more inflammation, are more likely to gain weight and develop cardiovascular disease,’ says Professor Spector.
Three weeks later, users get their results in three reports detailing their response to sugary and fatty foods, and the balance between good and bad gut bacteria.
In the meantime, the app will have calculated scores out of 100 for millions of everyday foods, based on the analysis. The lower the score, the less your body handles it.
The goal is to achieve a score of 75 at each meal, and anything below about 25 is marked as bad. Personalized weekly meal plans, created by the app, do the hard work.
Professor Spector explains, “Have a bagel. For me, a bagel is worth two because it raises my blood sugar dramatically, the fat in it hangs around in my blood, and it contains very little to help my microbiome.
“The app could tell me to eat it every two weeks, rather than every day.” However, according to Dr. Duane Mellor, head of nutrition at the University of Aston, the spikes and dips in blood sugar aren’t that big of a deal. “If you have type 1 diabetes, these sensors are good because people need to be able to judge how much insulin they’re injecting, based on how much their blood sugar levels are rising.” But that’s because they don’t produce enough insulin.
“For everyone… it’s normal to have a spike in blood sugar after eating, and it usually goes away within a few hours.”
Dr. Mellor questions the accuracy of glucose tracking. “There are a number of hormones that can interact with blood sugar and affect results. Hormones released upon waking can cause particularly high blood sugar spikes.
“And heavy exercise after eating triggers the release of adrenaline, which keeps blood sugar higher for longer. You would have to eat the same food three or four times under the same circumstances to be sure that the food itself is causing the blood sugar.
What about the evidence linking irregular blood sugar to obesity and heart disease? “You won’t necessarily have better blood sugar control by following,” says Dr. Mellor. “It’s best to work with a nutrition professional who can help you choose foods that are known to keep us full longer and learn to better listen to your body’s hunger cues.”
A 2018 review of available evidence in the British Medical Journal concluded that continuous blood glucose monitors are no more effective in helping people lose weight than an educational session with a trained dietitian.
There are also questions about what ZOE defines as good and bad gut bacteria.
Glenn Gibson, professor of food microbiology at the University of Reading, has spent 20 years researching the intricacies of gut bacteria – and their effects.
He says: “I wonder if a single stool sample gives an accurate representation of existing gut bugs, as they change in response to a whole host of factors – like food and exercise. You need to take several samples weeks apart to find out what gut bacteria someone has. Dr. Mellor adds, “Ultimately, foods high in good gut bacteria tend to be fruits, vegetables, nuts, and whole grains like wholegrain bread.
“Do we really need to pay £400 and take a fancy test to know that eating more broccoli and apples is probably good for us?”
Dr. Mellor believes that the risks outweigh the benefits. “Checking your glycemic response every time you eat something is no different from obsessive calorie counting, which we see in people with eating disorders,” he says. “You’re just using technology to justify a dysfunctional relationship with food.”
Destini Moody, a registered dietitian concerned with personalized nutrition, caters primarily to athletes and is based in Los Angeles, where continuous blood glucose monitors are popular with athletes.
She says, “They always want to try things that put them above everyone else. I do not see how it can be beneficial to observe the complex processes of the normal functioning of the body.
The diets failed but with ZOE I lost a stone… even if I became a little obsessive
JULIE Holton knows all too well about failed diets.
The 57-year-old, pictured above with her son Thomas, has spent the past decade struggling to lose two stones gained since menopause.
“I’ve tried everything — low-carb, plant-based, and psychology-based programs,” says Julie, who lives in Florida, where she runs an antique store.
‘Nothing worked. I was confused because I didn’t think I was eating badly. I had porridge for breakfast and rice and chicken for lunch and dinner, with lots of vegetables.
After hearing about ZOE from her doctor last year, she signed up. “I found the tests pretty easy to do, even though the muffins were gross,” she says.
Julie loved the instructor: “It was fascinating to watch. I had a chicken burger one night and felt really tired.
“I checked the app and saw that my blood sugar had dropped.” Julie has radically revised her diet. “The porridge didn’t fare well for me, so I swapped it for an egg white omelette, and my lunches are now salads with seeds and nuts.
She lost a stone in seven months.
She says: “At first I was a bit obsessed with reviewing my blood sugar and checking scores for each food, but now I have a rhythm.”