It’s not a myth: When you eat can contribute to your weight loss goals. It’s no longer just about portions, sugar and macronutrients. Timing is important.
A study published in the International Journal of Behavioral Nutrition and Physical Activity found that two habits may be connected to a lower body mass index over time: eating breakfast earlier and extending the overnight fasting period.
The research was led by scientists at the Barcelona Institute for Global Health (ISGlobal).
How the Study Tracked Meal Timing and BMI
The findings come from data involving more than 7,000 adults between 40 and 65.
All participants were part of the GCAT | Genomes for Life cohort.
In 2018, participants completed detailed questionnaires. They reported their height, weight, eating schedules, lifestyle habits and socioeconomic information.
In 2023 more than 3,000 participants returned for follow-up evaluations.
Early Meals and Longer Overnight Fasting
People who stopped eating earlier in the evening and then ate breakfast earlier the next day tended to have lower BMI levels over time.
Researchers believe this may relate to circadian rhythms. The body’s internal clock influences how energy is used, how hormones regulate appetite and how efficiently calories are burned.
Eating earlier in the day may better align with these natural biological cycles.
When meals occur later at night, metabolism and appetite regulation may not work as efficiently.
However, the researchers emphasize that the evidence is still evolving.
It may also be possible that those with healthy lifestyle habits (which would give rise to a lower BMI) are just more likely to eat breakfast earlier and avoid late evening eating.
Gender Differences in Lifestyle Habits
The study also uncovered several differences between men and women.
Women in the study generally had lower BMI values and were more likely to follow a Mediterranean-style diet. They also tended to drink less alcohol.
At the same time, women reported worse mental health overall and were more likely to be responsible for supervising household or family tasks.
A Small Group of Men with Very Late Eating Patterns
Researchers used a statistical technique called cluster analysis to group participants who shared similar behaviors.
One small group of men stood out.
These men typically ate their first meal after 2:00 p.m. and fasted for around 17 hours each day.
In many cases, this meant they were skipping breakfast entirely.
Compared with other participants, this group also had several other characteristics.
They were more likely to smoke and drink, less likely to exercise regularly and less likely to follow the Mediterranean diet.
They also tended to have lower levels of education and higher unemployment rates.
Interestingly, researchers did not find a similar pattern among women in the study.
Intermittent Fasting and Skipping Breakfast
There are several types of intermittent fasting, but one common approach is simply extending the overnight fasting window.
Some people do this by delaying breakfast or skipping it altogether.
In the subgroup of men who skipped breakfast, researchers did not observe any meaningful effect on body weight.
Other intervention studies have found similar results. For obese people, skipping breakfast as part of intermittent fasting doesn’t appear to produce greater long-term weight loss than does simply reducing daily calorie intake.
Possible Health Benefits of Eating Earlier
This new study builds on earlier chrononutrition (analysis of how timing of food intake affects nutritional consequences) research from ISGlobal.
Previous findings have suggested that eating dinner and breakfast earlier in the day may be linked to a lower risk of several chronic diseases.
These include cardiovascular disease and type 2 diabetes.
Taken together, the evidence hints that meal timing could be an important — and often overlooked — factor in long-term health.
The study does point out that more research is needed, but these findings certainly make a mark.
