ZOE snacking study: What should you do?

You might have heard that snacking is bad for you, but is that really true? 

Because there’s been little research into snacking’s impact on health, ZOE’s scientists decided to investigate

But understanding the links between snacking and health isn’t as straightforward as you might think — there’s a lot to consider: 

  • when you snack

  • what you snack on

  • how many times a day you snack 

  • how much energy you get from your snacks

Below, we’ll explain what we did, what we found, and what it means for you. 

Spoiler alert: Snacking isn’t necessarily bad, but there are some key factors to keep in mind.

What did we do?

We used data from 854 participants aged 18–65 who had enrolled in ZOE’s PREDICT 1 study

Each participant provided detailed information about what they ate and when. They also logged their hunger levels. 

We took several measures, including belly fat, body mass index (BMI), and levels of fat and sugar in the participants’ blood.

We also tested their blood fat and blood sugar responses to food.

These measures are important. After eating, it’s normal for fat and sugar to enter your blood. But if sugar or fat stays in your blood for too long, it can be bad for your health in the long run. 

What did we find?

Our analysis showed that 95% of people ate at least one snack every day. And, on average, snacks accounted for almost one-quarter of participants’ daily calories.

Frequency, quantity, and health

We searched for links between how frequently people snacked, how many calories they got from snacks (we called this “quantity”), and their health. 

Perhaps surprisingly, we didn’t find any links. 

How often people snacked and how many calories they got from it weren’t linked to weight, BMI, visceral fat, levels of blood fats, or blood sugar responses to food.

In other words, the frequency and quantity of your snacks don’t seem to harm your health.

So, what aspects of snacking do influence your health?

Quality matters

Low-quality snacks include cakes, candy, and cookies, while high-quality snacks include nuts, seeds, and fruit.

And unlike frequency and quantity, quality does make a difference to your health. 

Eating lower-quality snacks was linked to poorer health measures, including higher levels of fat and sugar in blood, poorer blood fat responses after eating, and insulin resistance.

Insulin resistance means your body doesn’t respond as well to insulin. So, it’s harder to move sugar away from your blood to be used as energy.

People who ate poor-quality snacks also reported feeling more hungry than those who ate good-quality snacks.

Ultra-processed snacks

Participants who mostly ate unprocessed and minimally processed snacks did better on some health measures, compared with people who mostly ate ultra-processed snacks.

For instance, they had lower body weight, less belly fat, lower levels of fat and sugar in their blood, and better blood fat responses to food.

Surprisingly, BMI and measures of belly fat were lower in people who ate high-quality snacks than those who didn’t eat any snacks at all.

Snack quality wasn’t the only factor to influence health, though.

What about timing?

We found that people like to snack at different times:

  • 13% ate most of their snacks in the morning (before midday)

  • 39% ate most of their snacks in the afternoon (between midday and 6 p.m.)

  • 31% ate most of their snacks in the evening (after 6 p.m.)

  • 17% were grazers — they ate snacks randomly throughout the day

These differences seem important for your health.

People who snack in the morning tend to eat higher-quality snacks and take on fewer calories from their snacks than those who snack at other times.

Late-evening snackers, who mostly snack after 9 p.m., performed worse on some health measures than those who snacked at all other times.

They had higher blood sugar levels and poorer blood sugar and blood fat responses after eating.

Similarly, late-evening snackers with low-quality snacks had poorer health measures than late-evening snackers with good-quality snacks.

So, if you snack later in the evening, choosing higher-quality snacks may reduce the unfavorable effects.

What should you do?

Despite what you might have heard, snacking isn’t necessarily bad for you — the important factors are quality and timing.

If you tend to snack later in the evening, try to move your snack schedule earlier in the day.

And when you snack, choose high-quality foods. Our research shows that this is linked to better blood sugar and blood fat responses and reduced hunger.

Kate Bermingham, Ph.D., is ZOE’s senior nutrition science manager, a researcher at King’s College London, and lead author of the study on snacking. 

We asked Kate for her advice. She said, “Many of us rely on snacking because life is busy and we’re on the go. So, when you’re choosing a snack, opt for something high-quality, like fruit or nuts and seeds.”

A mismatch

We also asked Kate which of the study’s findings surprised her the most.

“It surprised me that many people are discordant for snacking and main meal behavior. In other words, some people have high-quality meals but poor snack quality, or vice versa.”

For instance, more than 1 in 4 people consumed high-quality main meals but low-quality snacks. 

If this is you, simply switching your snack choices could make a real difference to your overall diet and health.

And if you’d like to learn more, we have a podcast on snacking featuring our scientific co-founder, Prof. Tim Spector, and our chief scientist, Dr. Sarah Berry.


Snack quality and snack timing are associated with cardiometabolic blood markers: The ZOE PREDICT study. European Journal of Nutrition. (2023). https://link.springer.com/article/10.1007/s00394-023-03241-6