When it comes to losing weight, it's often the simplest advice that sticks and has the most noticeable benefits for our long-term health. For example, switching to the Mediterranean diet or the Nordic diet, or eating fewer ultra-processed foods.
While there's nothing new about intermittent fasting, a study has examined how meal timing affects body mass index (BMI). Researchers, led by a team from the Barcelona Institute for Global Health (ISGlobal) in Spain, analysed diet and weight data from 7,074 people aged 40 to 65 from 2018 to 2023.
They found that people (especially pre-menopausal women) who ate breakfast earlier in the day and had an early dinner showed lower BMI scores after five years.
Extending the time between the last meal of the day and the first of the next day helps people maintain a healthy weight. The experts say this is because eating earlier in the day follows our circadian rhythm (the body’s natural sleep-wake cycle), which allows for more efficient calorie burning and appetite regulation.
The study, published in the International Journal of Behavioral Nutrition and Physical Activity, also found that skipping breakfast or having a later breakfast, certain sleep patterns, and whether participants ate between these two meals were linked to a higher BMI in both men and women.
Sleep is often flagged as a key contributor to weight loss. Without enough good core sleep, ghrelin (a hunger hormone) rises and leptin (a hormone that tells us we're full) lowers, which can make us feel hungrier. Eating between meals (snacking) is also a key contributor to weight gain for some people, per another study by Leeds Beckett University.
"Our results, in line with other recent studies, suggest that extending the overnight fast could help maintain a healthy weight if accompanied by an early dinner and an early breakfast," says epidemiologist Luciana Pons-Muzzo of ISGlobal. They found that meal timing patterns could be related to obesity in women.
Previous studies, such as this one from the University of Catania, found that people who ate their meals within eight to 10 hours of each other were less likely to be obese, overweight and have high blood pressure.
Further research may see how a long overnight fast and an early breakfast affect the way our body stores fat, but the study from Spain shows how eating patterns affect our overall health.
"Our research is part of an emerging field of research known as chrononutrition, which focuses not only on analysing what we eat, but also the times of day and the number of times we eat," says epidemiologist Anna Palomar-Cros of ISGlobal.
"At the basis of this research is the knowledge that unusual food intake patterns can conflict with the circadian system, the set of internal clocks that regulate the cycles of night and day and the physiological processes that must accompany them."
How to plan your mealtimes
- Eat earlier in the day: Aim to have breakfast first thing in the morning if you're trying to lose weight healthily, as later meal times were associated with higher BMI.
- Have an earlier dinner: Eating earlier in the day can extend the overnight fast without leaving you feeling like you've not eaten in hours.
- Limit snacks: Eating between meals contributed to weight gain for some participants.
- Get better sleep: Having an earlier dinner may also help boost your sleep quality as you won't be trying to digest your meal while you're drifting off.
What works for one person won't work for another. If your financial situation allows, it’s worth speaking to a dietitian or nutritionist who will help you create an individualised meal plan. You should also speak to your doctor before starting a new way of eating.
