Eating lunch after 3pm will make you fat, study says Eating lunch after three pm will cause you to gain 30 percent more weight than if you eat earlier. TAKING a late lunch makes it much harder for people to lose weight, according to researchers. Those who ate before 3pm lost 30 per cent more weight than those who dined later in a 420-strong group of people taking part in a 20-week diet. Half of the group ate lunch - their biggest meal of the day - before 3pm, while half ate later. Those eating early lost an average of 22lb, 5lb more than the late eaters, reveals a report in the International Journal of Obesity. Analysis by researchers from Brigham and Women's Hospital in Boston and the Spanish University of Murcia found that late lunchers were more likely than others to have a light breakfast or none at all. Although the team could not say why weight loss came easier to those who ate earlier, it is possible that sugar is processed differently depending on the time of day, or that meal times affect the processing of fat. Researcher Frank Scheer, of Harvard Medical School, said that in countries where the biggest meal of the day is eaten in the evening, such as Britain, having a late dinner may also impede weight loss. Ian Campbell, a GP and medical director of charity Weight Concern, said: "People who have breakfast tend not to snack mid-morning and eat healthier during the day."