Media playback is unsupported on your device Media caption How healthy is your breakfast choice?

Breakfast is the most important meal of the day - it's a great start, it's good for you, it stops you snacking, boosts metabolism and keeps you thin.

Well, that's what we've all been told.

But some scientists argue this is all a myth - and that just because we keep repeating it doesn't make it true.

So should we bother with breakfast?

Studies repeatedly show that skipping breakfast is more common in people who are overweight or obese.

But this could be a dangerous trap - when the number of ice cream sales goes up so does the number of people getting sunburn. It doesn't mean ice-cream is causing sunburn.

This association might be down to something special about brekkie - or maybe the type of people who eat it are generally more active, have a better overall diet or try to lead healthier lives.

Despite advocating breakfast as part of a healthy lifestyle, a report by the UK's National Obesity Observatory concluded that "it is not clear whether there is a causal relationship with Body Mass Index (weight) or whether breakfast is merely a marker for other lifestyle factors that can contribute to healthy body weight".

Breakfast on trial

The few clinical trials that have actively altered people's eating habits also showed no impact on waistlines.

The biggest, published in the American Journal of Clinical Nutrition, told 300 overweight or obese people to skip or eat breakfast for four months.

"There was absolutely no difference whatsoever in the amount of weight-loss," said Prof David Allison, who conducted that trial at the University of Alabama.

"With respect to weight, at least in adults, it looks like we're leaning towards it [breakfast] being a myth."

He says people who are skipping breakfast are probably just trying to control their own weight.

And one danger for skippers who start having breakfast is it could lead to weight gain, if they don't eat less later in the day.

So is government advice plain wrong?

In Prof Allison's opinion: "If they are advising it [breakfast] for weight control then at this point it is not a justified recommendation."

Image copyright Thinkstock Image caption Who can resist the fry-up?

Dr Alison Tedstone is from one of the many organisations around the world that tells us breakfast is a good thing, and she points to studies showing people who skip breakfast tend to be bigger, which we already know is an association.

But Dr Tedstone, chief nutritionist at Public Health England, agrees that the "evidence is by no means conclusive on having breakfast".

However, she says it is the easiest meal of the day to get right, that skipping it risks snacking on something unhealthy later on and that it can be a struggle to get the right balance of nutrients without starting the day well.

"It's an easy meal to get a healthy meal, it's an easy meal to get control over."

What makes a healthy breakfast?

Image copyright Thinkstock

There is no such thing as a perfect breakfast, but Dr Tedstone advises people to "think fibre" in the mornings.

"Overall we're not getting enough fibre in our diet and it's easy to incorporate fibre into breakfast.

"Take porridge - it's cheap, it's cheerful," she said.

As well as porridge, high fibre breakfasts include fruit, wholegrain toast and some breakfast cereals.

But some of the more palatable high-fibre cereals can be loaded with added salt and sugar.

Prof Susan Jebb, a nutrition scientist at the University of Oxford says: "It is very difficult, I think breakfast cereals are very challenging."

She says it's necessary to check the labels as some have less added sugar and that fresh, stewed or dried fruit could be used to make it more palatable.

"I'd encourage people to have a piece of fruit with breakfast - much better to have fruit than fruit juice as then you get the fibre from the intact fruit."

NHS: Healthy Breakfasts

Brain fuel

The other big case made for breakfast is that it improves children's performance in school.

A study in 2015 by the University of Cardiff was the latest to show an association between a healthy breakfast and educational performance in the classroom.

These studies are now coming in for the same criticism as those that found a link between breakfast and weight.

"It seems very plausible that missing breakfast as a kid is just a marker of a poor home background - that family is unable to provide breakfast for a child - which is probably the cause of them not performing well at school," argues Prof David Rogers at the University of Bristol.

So how do we make sense of all this?

Prof Jebb argues: "If you're currently eating breakfast I think you should make it the healthiest breakfast you can.

"If you're a breakfast skipper, I'm certainly not going to say you must eat breakfast, but I would encourage you to think about it."

While Prof Allison suggests people who are worried about their weight should give both eating and skipping breakfast a go to see what works best for them - just make sure you're not snacking on sausage rolls by 11:00.

The science behind the benefits of breakfast does not support the absolute vehemence with which it is advocated, at least in adults.

That said I'm still going to have my bowl of breakfast cereal.

It is a good start to the day for me personally otherwise I'm distractingly hungry. I might even try chucking in a bit of extra fruit.

Follow James on Twitter.