Scientists Identify Two Key Habits Linked to a Lower BMI
By Barcelona Institute for Global Health (ISGlobal)
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This research was led by the Barcelona Institute for Global
Health (ISGlobal), a center supported by the “la Caixa” Foundation.
The study involved more than 7,000 volunteers aged 40-65
from the GCAT | Genomes for Life cohort, a project led by the Germans Trias i
Pujol Research Institute (IGTP).
In 2018, participants answered questionnaires about their
weight and height, eating habits including meal times, other lifestyle habits,
and socioeconomic status. In 2023, after five years, more than 3,000
participants made a follow-up visit to the research team, where their measures
were registered again and new questionnaires were completed.
Interpretation of results
“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. We think this may be
because eating earlier in the day is more in line with circadian rhythms and
allows for better calorie burning and appetite regulation, which can help
maintain a healthy weight. However, it is too soon to draw definitive
conclusions, so recommendations will have to wait for more robust evidence,”
explains Luciana Pons-Muzzo, a researcher at ISGlobal at the time of the study
and currently at IESE Business School.
Gender differences
Analysis of the data by gender showed that, compared to men,
women generally showed lower BMI, higher adherence to the Mediterranean diet,
lower propensity to consume alcohol, poorer mental health, and were more likely
to be responsible for household or family supervision.
The team used a statistical technique called ‘cluster
analysis’ to group individuals with similar characteristics. From the results
of this analysis, the authors were struck by a small group of men whose first
meal of the day was after 14:00 and who, on average, fasted for 17 hours.
Compared to the rest, this group of men tended to have less healthy lifestyles
(more likely to smoke, drink alcohol, less physical activity, less adherence to
the Mediterranean diet), and had lower levels of educational attainment, and
were more likely to be unemployed. These patterns were not observed in any
group of women.
On intermittent fasting
“There are different ways of practicing what is known as
‘intermittent fasting’ and our study relates to one of them, which is overnight
fasting. What we observed in a subgroup of men who do intermittent fasting by
skipping breakfast is that this practice has no effect on body weight. Other
intervention studies in participants with obesity have shown that this tactic
is no more effective than reducing calorie intake in reducing body weight in
the long term,” says Camille Lassale, ISGlobal researcher and senior co-author
of the study.
“Our research is part of an emerging field of research known
as ‘chrononutrition’, which focuses not only on analyzing what we eat, but also
the times of day and the number of times we eat,” says Anna Palomar-Cros, a
researcher at ISGlobal at the time of the study and currently at IDIAP Jordi
Gol.
“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,” she adds.
Previous studies
This study provides continuity to a line of ISGlobal
research on chrononutrition, which in recent years has published two other
studies with results in the same direction. In these studies, it was observed
that eating dinner and breakfast early was associated, respectively, with a
lower risk of cardiovascular disease and type 2 diabetes.
Reference: “Sex-specific chrono-nutritional patterns and
association with body weight in a general population in Spain (GCAT study)” by
Luciana Pons-Muzzo, Rafael de Cid, Mireia Obón-Santacana, Kurt Straif, Kyriaki
Papantoniou, Isabel Santonja, Manolis Kogevinas, Anna Palomar-Cros and Camille
Lassale, 12 September 2024, International Journal of Behavioral
Nutrition and Physical Activity.
DOI: 10.1186/s12966-024-01639-x