The mantra of breakfast being the most important meal of the day has been ingrained in most of us from an early age—from our mother’s mouth as we were late for school to government campaigns to get us to “go to work on an egg.” Over the past 50 years we have been bombarded with messages extolling the health benefits of various processed cereals and porridge oats. The British fry-up is thought by many to be the country’s main contribution to world cuisine.

We are told that breakfast helps our metabolism and that skipping it will make us much hungrier so we’ll overeat and put on weight. These are not just old wives’ tales. They are clearly laid out in current Public Health England and NHS guidelines prepared by an expert scientific panel with input from the food industry. These are mirrored in many other national guidelines, as well as the lay press and websites across the world. But what if this is just another diet myth?

The disadvantages of skipping breakfast have now been debunked by several randomised trials. A systematic review and meta-analysis of the 11 randomised trials of skipping breakfast performed to date is published today in this journal. The studies varied widely in duration and quality, and seven looked at changes in weight as well as changes in energy usage. The conclusions were the same as in recent, largely ignored qualitative reviews namely, that no evidence supports the claim that skipping breakfast makes you gain weight or adversely reduces your resting metabolic rate.

Furthermore, reasonable evidence now suggests that skipping breakfast can actually be a useful strategy to reduce weight. Why has the specialty got it so wrong in the past? There are several possible reasons, linked to traditional beliefs about nutrition. We are told to eat little and often—“grazing” rather than “gorging” to avoid “stress” on the body from having to digest large meals, especially later in the day when glucose peaks are higher and metabolic rates lower. The rationale was based on multiple studies of small animals and a few short term studies in humans. The concept of over-compensation later in the day was correct, and people who skip breakfast do eat more lunch and slightly reduce their activity—but importantly not nearly enough to make up the lost energy intake.

The other reason that experts were misled was because multiple observational studies have shown that obese and diabetic people skipped meals more often than thin people. This mindset became ingrained in nutritional dogma. But these observational studies were flawed by bias. People who skipped breakfast were more likely on average to be poorer, less educated, less healthy, and to have a generally poorer diet. Overweight people were more likely to try and diet, and after a binge were more likely to feel guilty and skip a meal.

Despite these flaws in the science and the steady increase in opposing evidence from randomised controlled trials, the idea that skipping meals is unhealthy has prevailed for decades.Not skipping breakfast is still part of current NHS recommendations by Public Health England and one of its eight key healthy diet messages, part of the United States Department of Agriculture diet guidelines for Americans, and the current Australian Guidelines for Nutrition. Another common argument by the pro-breakfast lobby is that as well as reducing obesity, breakfast is essential for the mental wellbeing of children, even if they are generally well nourished. Again the evidence is weak, largely observational, and likely biased in the same way as for adults.

Evidence is also accumulating that restricting eating times and increasing fasting intervals can help certain people to lose weight. Some of these recent developments that seem counterintuitive to traditional thinking make sense in the context of the importance of the gut microbiome on human health and metabolism. The community of 100 trillion gut microbes have a circadian rhythm and vary in composition and function in fasting and fed states. Although this is a young discipline, some data suggest that microbial communities could benefit from short periods of fasting. They, similar to us, might need to rest and recuperate, which could be important for gut health in humans.

Around a third of people in developed countries regularly skip breakfast, whereas many others (including myself) enjoy it. This does not mean that all overweight people would benefit from skipping breakfast. Some people are programmed to prefer eating food earlier in the day and others later, which might suit our unique personal metabolism. No “one size fits all,” and prescriptive slow moving diet guidelines filled with erroneous information look increasingly counterproductive and detract from important health messages. While waiting for guidelines to change, no harm can be done in trying out your own personal experiments in skipping breakfast.

Tim Spector, professor of genetic epidemiology, King’s College London

Competing interests: TS receives royalties from book The Diet Myth: the science behind what we eat Orion 2016, and is scientific founder of Zoe Global Ltd (a personalised nutrition company). He has received research grants from Danone. TS is a regular breakfast eater.