If you wake up in the morning and you aren’t hungry and you know you will be sedentary for much of the day, say tied to a desk, then he questions the value of consuming unnecessary calories. But if you know you will be playing sport or exercising later, then it may make good sense to have breakfast even if you don’t feel like it because you might need the energy later.

“Our hypothesis from the start was that the type of activity most likely to respond to eating or skipping breakfast wouldn’t be waking up and thinking ‘I must go to the gym or run for an hour’, but would be the really subtle changes in low-intensity lifestyle activities,” says Betts.

A person – depending on size – uses up about a calorie a minute in a sedentary state. Given that there are 1,440 minutes in a day, that explains why the average resting metabolic rate is about 1,500 calories a day.

While most people think they only start expending calories when they are exercising, he notes you can actually clock up a large energy expenditure just by exchanging sedentary activity for very low-level lifestyle activity.

Eating breakfast causes obese people to be more active, according to a recent report by the Bath researchers published in the American Journal of Clinical Nutrition. The study analysed the links between breakfast and health for people classed as obese, comparing the results from a fasting group with a breakfasting group.

The key insight: eating breakfast did not make obese people lose weight, but did result in more physical activity in the morning and reduced food intake later in the day, meaning that both groups ate similar amounts overall.

The message from this, the researchers say, is that increasing activity is one of the most important ways to improve health in our increasingly sedentary population.

Another commonly held belief is that breakfast helps kick-start your metabolism. Betts disagrees, saying the impact is minimal – data shows a difference of three to 10 calories in resting metabolism.

There is a slight increase in metabolism directly after a meal – known as dietary-induced thermogenesis – which Betts says is predictable, with most people expending 10 per cent of the calories received from the food.

As to why so many of us hold the conviction that breakfast is the most important meal of the day, Betts points to a study by the University of Alabama at Birmingham (also published in the American Journal of Clinical Nutrition) that took a sociological approach to the question and concluded that the blame should be shared equally between scientists, the media and the public.

“The researchers found that lots of scientists that use a cross-sectional approach inappropriately use causal language, and journalists are seeing papers that ostensibly show cause and effect. Then there’s the breakfast industry that has an incentive to get the message out about breakfast,” says Betts.

Many people in their 40s and 50s will have grown up with parents quoting the adage: “Eat breakfast like a king, lunch like a prince and dinner like a pauper.” That’s the advice popular American nutritionist Adelle Davis laid out in her 1947 book, Let’s Cook it Right.

There seems a simple logic to the statement – eat more in the morning and you’ll have all day to burn off the calories, but Betts says it’s not helpful to measure energy balance on a daily basis.

“Feeling full due to the food in our bellies or the effect of hormones doesn’t always achieve our energy balance on a daily basis. It happens over many days,” he says.

He believes the solution to obesity lies in looking at both sides of the equation: calories in and calories out. This is because of the body’s compensatory mechanisms, whereby if you eat more or less your body will naturally do more or less. Equally, if someone is prescribed two hours exercise on a treadmill each day, they will naturally compensate by eating more.

So should we be eating breakfast or not? It really depends on the individual and what they want to achieve. If weight loss is your goal, there is little evidence in the research to suggest that eating breakfast or skipping it will matter.

However, based on the markers of a healthy lifestyle such as being more active and controlling blood sugar levels, there is evidence that eating breakfast may help.

“If you have breakfast, take advantage of the fact that you will be more active. And if you’re fasting, be aware that you are naturally going to be less active and try and cut corners where you can,” says Betts.

Betts and fellow researcher Dr Enhad Chowdhury will conduct further experiments comparing different breakfast types.

They aim to find out what is especially satiating for those who eat breakfast and whether, for those who skip breakfast and are less active, there is there something else they could consume to make them more active.

“Perhaps caffeine could increase physical activity levels without the need to take in calories,” says Betts, who has a background in sports nutrition. “[Caffeine] is one of the most versatile and effective supplements out there for taking part in exercise – it motivates you, stimulates strength, speed, and endurance performance. It’s really quite beneficial.”