Fasting earlier or later in day ‘effective strategy for long-term weight loss'

Irish Examiner

11-05-2025

Fasting earlier or later in the day for three months could be an effective strategy for long-term weight loss, research suggests.
Experts found that overweight or obese people who restricted eating to an eight hour 'window' per day shed pounds and managed to keep it off.
The new research, which has not yet been published in a peer-reviewed journal, was presented at the European Congress on Obesity in Malaga.
Lead author Dr Alba Camacho-Cardenosa, from the University of Granada in Spain, said: 'Our study found that restricting the eating window to eight hours at any time of the day for three months can result in significant weight loss for at least a year.
'These benefits can be attributed to the 16-hour fasting window rather than the time of eating.'
A previous randomised controlled trial by the same researchers published in the journal Nature Medicine found that restricting eating to eight hours per day decreased body weight and improved cardiometabolic health.
This kind of intermittent fasting appears feasible for adults with overweight or obesity who wish to have a relatively simple way of losing and maintaining weight loss
Their latest study looked at the long-term effects over 12 months for 99 people.
Individuals were split into four groups for 12 weeks – eating in a 12-hour or more window; restricting eating to an eight-hour window starting before 10am; restricting eating to an eight-hour window starting after 1pm; and allowing people to select their own eight-hour window.
All groups were given tips on a Mediterranean diet to help them eat healthier.
The researchers measured body weight, waist and hip circumferences at the start of the trial, after the 12-week plan, and 12 months later.
The study found that, while those eating over 12 hours or longer lost an average of 1.4kg, the time-restricted groups lost more, at around 3kg to 4kg.
Time-restricted groups also had greater reductions in waist and hip circumferences of several centimetres, and had maintained greater weight loss after 12 months.
At the one-year mark, those eating for 12 hours or more had an average body weight increase of 0.4kg, compared with around a 2kg weight loss in the early and late time restricted groups, the study concluded.
Those who chose their own pattern also maintained some weight loss although this was not statistically significant.
Around 85% to 88% of people restricting their eating window also found they stuck to the plan.
Dr Jonatan Ruiz, study co-ordinator from the University of Granada, said: 'This kind of intermittent fasting appears feasible for adults with overweight or obesity who wish to have a relatively simple way of losing and maintaining weight loss that is less tedious and more time efficient compared with daily calorie counting, but it warrants further investigations in larger and longer-term studies.'
Dr Maria Chondronikola, principal investigator and lead for human nutrition at University of Cambridge Metabolic Research Laboratories, said further studies were needed.
'Understanding how well participants adhered to the timing of their meals, the level of their caloric intake and whether time-restricted eating changed any obesity-related metabolic outcomes would provide valuable insight into the true effectiveness of time-restricted eating,' she said.