We’ve all heard that healthier, fitter people don’t skip breakfast. But does that mean breakfast makes us healthier and thinner – or is it something else? Along with old classics like ‘carrots give you night vision’ and ‘Santa doesn’t bring toys to misbehaving children’, one of the most well-worn phrases in the arsenal of tired parents everywhere is that breakfast is the most important meal of the day. Many of us grow up believing that skipping breakfast is a dietary travesty – even if only two thirds of adults in the UK eat breakfast regularly, according to the Association of UK Dieticians (BDA), and around three-quarters of Americans.

The clue for why breakfast is supposed to be important is in its name: we’re advised to eat it to break our overnight fast.

“The body uses a lot of energy stores for growth and repair through the night,” explains dietician Sarah Elder. “Eating a balanced breakfast helps to up our energy, as well as protein and calcium used throughout the night.”

It's true that eating a balanced breakfast helps restore our energy after a night's fast

But there’s widespread disagreement over whether breakfast should keep its top spot in the hierarchy of meals. As well as the rising popularity of fasting diets, there have been concerns around the sugar content of cereal and the food industry’s involvement in pro-breakfast research – and even one claim from an academic that breakfast is “dangerous”.

So what’s the reality? Is breakfast a necessary start to the day… or a marketing ploy by cereal companies?

Weighty decision

The most researched aspect of breakfast (and breakfast-skipping) has been its links to obesity. Scientists have different theories as to why there’s a relationship between the two.  

In one US study that analysed the health data of 50,000 people over seven years, researchers found that those who made breakfast the largest meal of the day were more likely to have a lower body mass index (BMI) than those who ate a large lunch or dinner. The researchers argued that breakfast helps increase satiety, reduce daily calorie intake, improve the quality of our diet – since breakfast foods are often higher in fibre and nutrients – and improve insulin sensitivity at subsequent meals, which can be a risk for diabetes.

 

One analysis found that people who made breakfast the biggest meal were more likely to have a lower body mass index

But as with any study of this kind, it was unclear if that was the cause – or if breakfast-skippers were just more likely to be overweight to begin with.

To find out, researchers designed a study in which 52 obese women took part in a 12-week weight loss programme. All had the same number of calories over the day, but half had breakfast, while the other half did not.

What they found was that it wasn’t breakfast itself that caused the participants to lose weight: it was changing their normal routine. The women who said before the study that they usually ate breakfast lost 8.9kg when they stopped having breakfast, compared to 6.2kg in the breakfast group. Meanwhile, those who usually skipped breakfast lost 7.7kg when they started eating it – and 6kg when they continued to skip it.

If breakfast alone isn’t a guarantee of weight loss, why is there a link between obesity and skipping breakfast?

Alexandra Johnstone, professor of appetite research at the University of Aberdeen, argues that it may simply be because breakfast-skippers have been found to be less knowledgeable about nutrition and health.

“There are a lot of studies on the relationship between breakfast eating and possible health outcomes, but this may be because those who eat breakfast choose to habitually have health-enhancing behaviours such as not smoking and regular exercise,” she says.

People who eat breakfast may just be more health-conscious overall – rather than breakfast making them healthier

A 2016 review of 10 studies looking into the relationship between breakfast and weight management concluded there is “limited evidence” supporting or refuting the argument that breakfast influences weight or food intake, and more evidence is required before breakfast recommendations can be used to help prevent obesity.

Feast or fast?

Intermittent fasting, which involves fasting overnight and into the next day, is gaining ground among those looking to lose or maintain their weight or improve their health.  

One pilot study published in 2018, for example, found that intermittent fasting improves blood sugar control and insulin sensitivity and lowers blood pressure. Eight men with pre-diabetes were assigned one of two eating schedules: either eating all their calories between 9:00 and 15:00, or eating the same number of calories over 12 hours. The results for the 9:00-15:00 group were found to be on par with medicine that lowers blood pressure, according to Courtney Peterson, the study’s author and assistant professor of nutrition sciences at the University of Alabama at Birmingham.

Still, the study’s small size means more research is needed on its possible long-term benefits.

If skipping breakfast (and other food outside of a restricted time slot) could potentially be good for you, does that mean breakfast could be bad for you? One academic has said so, arguing that breakfast is ‘dangerous’: eating early in the day causes our cortisol to peak more than it does later on. This causes the body to become resistant to insulin over time and can lead to type 2 diabetes.

But Fredrik Karpe, professor of metabolic medicine at Oxford Centre for Diabetes, Endocrinology and Metabolism, argues this isn’t the case. Instead, higher levels of cortisol in the morning are just part of our body’s natural rhythm.

Not only that, but breakfast is key to jumpstarting our metabolism, he says. “In order for other tissues to respond well to food intake, you need an initial trigger involving carbs responding to insulin. Breakfast is critical for this to happen,” Karpe says.

Skipping breakfast – by only eating between 9:00 and 15:00 – was found to be beneficial in one small stud y

A randomised control trial published last year involving 18 people with, and 18 people without, diabetes found that skipping breakfast disrupted the circadian rhythms of both groups and led to larger spikes in blood glucose levels after eating. Eating breakfast, the researchers conclude, is essential for keeping our body clock running on time.

Peterson says those who skip breakfast can be divided into those who either skip breakfast and eat dinner at a normal time – getting the benefits of intermittent fasting, if not breakfast – or those who skip breakfast and eat dinner late.

“For those who eat dinner later, their risk of obesity, diabetes and cardiovascular disease goes through the roof. While it seems breakfast is the most important meal of the day, it might actually be dinner,” she says.

“Our blood sugar control is best early in the day. When we eat dinner late, that’s when we’re most vulnerable because our blood sugar is worst. There’s more research to do, but I’m confident you shouldn’t skip breakfast and have dinner late.”  

She says we should think of our circadian rhythm as an orchestra.

An initial ‘trigger’ with carbohydrates is critical for jumpstarting the metabolism 

“There are two parts of our circadian clock. There’s the master clock in the brain, which we should think of as analogous to a conductor of an orchestra, and the other half is in every organ, which has a separate clock,” she says.

And that ‘orchestra’ is set by two outside factors: bright light exposure and our eating schedule.

“If you’re eating when you’re not getting bright light exposure, the clocks that control metabolism are in different time zones, creating conflicting signals as to whether to rev up or down.”

It’s like two halves of an orchestra playing different songs, Peterson explains, and this is why eating late impairs blood sugar and blood pressure levels.

Researchers from the University of Surrey and University of Aberdeen are halfway through research looking into the mechanisms behind how the time we eat influences body weight. Early findings suggest that a bigger breakfast is beneficial to weight control.

Health food

Breakfast has been found to affect more than just weight. Skipping breakfast has been associated with a 27% increased risk of heart disease, a 21% higher risk of type 2 diabetesin men, and a 20% higher risk of type 2 diabetes in women.

One reason may be breakfast’s nutritional value – partly because cereal is fortified with vitamins. In one study on the breakfast habits of 1,600 young people in the UK, researchers found that the fibre and micronutrient intake, including of folate, vitamin C iron and calcium, was better in those who had breakfast regularly. There have been similar findings in Australia, Brazil, Canada and the US.

Because blood sugar control is best in the morning, it’s better to have a big meal early in the day – not late at night

Breakfast is also associated with improved brain function, including concentration and language. A review of 54 studies found that eating breakfast can improve memory, though the effects on other brain functions were inconclusive. However, one of the review’s researchers, Mary Beth Spitznagel, says there is “reasonable” evidence breakfast does improve concentration – there just needs to be more research.

“Looking at studies that tested concentration, the number of studies showing a benefit was exactly the same as the number that found no benefit,” she says.

“And no studies found that eating breakfast was bad for concentration.”

What’s most important, some argue, is what we eat for breakfast.

A bigger breakfast may help with weight control 

High-protein breakfasts have been found particularly effective in reducing food cravings and consumption later in the day, according to research by the Australian Commonwealth Scientific and Industrial Research Organisation.

While cereal remains a firm favourite among breakfast consumers in the UK and US, a recent Which? investigation into the sugar content of ‘adult’ breakfast cereals found that some cereals contain more than three quarters of the recommended daily amount of free sugars in each portion, and sugar was the second or third highest ingredient in seven out of 10 flaked cereals.

But some research suggests if we’re going to eat sugary foods, it’s best to do it early. One study found that changing levels of the appetite hormone leptin in the body throughout the day coincide with having our lowest threshold for sweet food in a morning, while scientists from Tel Aviv University have found that hunger is best regulated in the morning. They recruited 200 obese adults to take part in a 16-week-long diet, where half added dessert to their breakfast, and half didn’t. Those who added dessert lost an average of 40lbs (18kg) more – however, the study was unable to show the long-term effects.

Because many cereals are fortified with vitamins, breakfast-eaters often take in more nutrients… but also more sugar 

A review of 54 studies found that there is no consensus yet on what type of breakfast is healthier, and conclude that the type of breakfast doesn’t matter as much as simply eating something.

Final take

While there’s no conclusive evidence on exactly what we should be eating and when, the consensus is that we should listen to our own bodies and eat when we’re hungry.  

“Breakfast is most important for people who are hungry when they wake up,” Johnstonesays.

Eating breakfast may help to improve memory

For instance, research shows that those with pre-diabetes and diabetes may find they have better concentration after a lower-GI breakfast such as porridge, which is broken down more slowly and causes a more gradual rise in blood sugar levels.

 

Every body starts the day differently – and those individual differences, particularly in glucose function, need to be researched more closely, Spitznagel says.

In the end, the key may be to be mindful of not over-emphasising any single meal, but rather looking at how we eat all day long.

 

High-protein breakfasts help reduce food cravings later in the day 

“A balanced breakfast is really helpful, but getting regular meals throughout the day is more important to leave blood sugar stable through day, that helps control weight and hunger levels,” says Elder.

“Breakfast isn’t the only meal we should be getting right.”