Limited duration calorie restriction could aid in maintaining weight loss longevity.
In the last few years, the diet trend of intermittent fasting, also known as time-restricted eating, has skyrocketed in popularity. There's been quite a debate surrounding what time of the day the eating window should be scheduled for intermittent fasting — either early in the morning or later in the day.
However, a recent study featured at the European Congress on Obesity (ECO) 2025 has provided interesting insights. This study indicates that maintaining long-term weight loss is still possible through time-restricted eating, regardless of the time of day the eating window falls.
The researchers, led by Dr. Alba Camacho-Cardenosa from the Instituto de Investigación Biosanitaria de Granada (ibs.GRANADA), recruited 99 participants from Spain with an average age of 49 who were carrying excess weight. The participants were randomly assigned to one of four groups for 12 weeks:
- Habitual eating window of 12 hours or more
- Early time-restricted eating (8-hour eating window that starts before 10:00 am)
- Late time-restricted eating (8-hour eating window that starts after 1:00 pm)
- Self-selected time-restricted eating (8-hour eating window whenever the participant wanted it)
The scientists recorded the body weight, waist, and hip circumference of each participant at the beginning, after 12 weeks, and 12 months after the study's completion.
After 12 weeks, the researchers discovered that all time-restricted eating groups lost more weight than those in the habitual eating group. In the doubt, the approach of limiting the eating window appears to help people naturally reduce their calorie intake and lose weight.
Not only did all of the time-restricted eating groups lose weight, but they also showed reduced hip and waist circumferences. The group with the earliest eating window experienced the largest decline in these measurements.
At the 12-month mark, researchers found that participants in the habitual eating group gained weight back, while all three time-restricted eating groups had maintained their weight loss. Participants in the habitual eating group also displayed an increase in waist circumference after 12 months, while those in the time-restricted eating groups showed no such increase.
Dr. Camacho-Cardenosa stated, "The fact that participants were able to maintain weight loss after 12 months shows that time-restricted eating can be a sustainable long-term approach. This strategy doesn't just help people lose weight, but it can also help them maintain it, which is a significant challenge in most weight loss programs."
The study is still pending publication in a peer-reviewed scientific journal. Further work is needed to explore the effects of time-restricted eating combined with exercise on cardiometabolic health and ectopic fat depots, as well as to identify which types of people benefit most from specific eating windows.
Dr. Mir Ali, a board-certified bariatric surgeon, mentioned that the study confirms the benefits of time-restricted eating and that it might be valuable to investigate the impact of different diets like the Mediterranean or Paleo diets when combined with an eating window. He also suggested that further research should focus on finding the minimum time necessary for time-restricted eating to be effective.
For those interested in trying intermittent fasting, Monique Richard, a registered dietitian nutritionist, offered some guidance: Monitor your daily schedule to see how your eating times and nutritional needs fit together and consider adjusting them to an 8-hour eating window. Pay attention to why, how, what, and when you eat to make informed decisions about your meals. Additionally, remember that your body has a 'housekeeper' in the form of the migrating motor complex, which assists the gut in tidying up between meals and supports other digestive processes.
In summary, the study from the European Congress on Obesity (ECO) 2025 provides evidence that time-restricted eating can lead to significant and sustainable weight loss for individuals with overweight or obesity. By limiting the eating window to 8 hours, regardless of the timing, it is possible to reduce calorie intake, lose excess weight, and maintain that weight loss over an extended period. While further research is necessary, incorporating time-restricted eating into a healthy lifestyle may prove to be a valuable strategy for managing weight and improving overall health.
- The study at the European Congress on Obesity (ECO) 2025 suggests that time-restricted eating, regardless of the time of day, can aid in long-term weight loss.
- The researchers discovered that all time-restricted eating groups lost more weight than those who had a habitual eating pattern, indicating a natural calorie reduction.
- After 12 months, the participants who followed a habitual eating pattern gained weight back, while those in time-restricted eating groups maintained their weight loss.
- The study also indicated reduced hip and waist circumferences in all time-restricted eating groups, with the earliest eating window showing the largest decline.
- Further research is needed to explore the effects of time-restricted eating combined with exercise, as well as the optimal diet for specific eating windows, like the Mediterranean or Paleo diets.
