When breakfast is the biggest meal of the day, it may keep blood sugar levels stable and obesity at bay. This dietary practice may also help those with obesity lose weight, say researchers.

The energy we use to digest food (known as diet-induced thermogenesis) is a sign of metabolic health, and this can change depending on mealtime, said Juliane Richter, M.Sc., Ph.D., of the University of Lübeck, Germany. In a laboratory study, Richter and her colleagues had men eat their biggest (high calorie) meal at breakfast and then switch to big dinners. They found that it took the men significantly more energy to digest the big breakfast than it took them to digest a dinner that contained the same amount of calories.

“Our results show that a meal eaten for breakfast, regardless of the amount of calories it contains, creates twice as high diet-induced thermogenesis as the same meal consumed for dinner,” Richter said.

Notably, the mens’ blood sugar and insulin concentrations weren’t as high when they ate a large breakfast as when they ate a large dinner. Meanwhile, eating a small (low-calorie) breakfast appeared to increase appetite, mainly for sweets, throughout the day.

“We recommend that patients with obesity as well as healthy people eat a large breakfast rather than a large dinner to reduce body weight and prevent metabolic diseases,” Richter said.

The study was published online in The Journal of Clinical Endocrinology & Metabolism.