People trying to lose weight may need to consider not only what they eat but when they eat it.
Scientists who studied the timing of meals have discovered that people who ate late in the day lost less weight than those who ate earlier.
Even though they consumed the same total calories and expended the same energy, those who sat down to lunch late shed significantly fewer pounds than those who had their lunch early.
The finding turns conventional advice on its head. Nutritionists spend much of their time exploding dieting “myths” such as that eating at night leads to weight gain. Now they may have to reconsider.
The conventional view is that the body will store as fat any extra calories consumed beyond those burnt as energy during the day, regardless of the time of day during which those extra calories are consumed.
But it has been undermined by recent research in animals and humans suggesting that energy regulation and the laying down of adipose tissue (fat) is subject to a circadian rhythm, which , if disrupted, may lead to disturbances in metabolism.
Studies have shown that mice fed at night gained more weight than mice fed during the day, even though both groups consumed the same amount and moved around as much.
In humans, shift works are known to be more prone to obesity than day workers even though total energy used over 24 hours does not vary between them.
In the latest study, researchers led by Professor Frank Scheer, director of the Medical Chronobiology Programme at Harvard Medical School, Boston, US, working with scientists at the University of Murcia in Spain, studied 420 Spanish women who were on a 20 week weight loss programme.
The main meal of the day for this Mediterranean population was lunch which comprised 40 per cent of their total daily calorie consumption. Women who ate their lunch early – before 3 pm – lost significantly more weight than those who ate after 3pm. Late eaters also had a slower rate of weight loss. The findings are published in the International Journal of Obesity.
Professor Scheer said: "This is the first large scale, prospective study to demonstrate that the timing of meals predicts weight-loss effectiveness."
Professor Marcia Garaulet, a physiologist at the University of Murcia and lead author of the study, said: “Novel therapeutic strategies should incorporate not only caloric intake and macronutrient distribution, as it is classically done, but also the timing of food.”