The common notion that eating a big breakfast and light dinner helps people burn more calories may be misguided.
New research published Friday in the journal Cell Metabolism found that eating the bulk of one's calories in the morning doesn't help people lose weight any more than eating those calories at night.
The findings were based on a controlled experiment involving 30 adults in the U.K. who were obese or overweight. For four weeks, the participants followed one of two diets: About half of them consumed 45% of their daily calories at breakfast, followed by 35% at lunch and 20% at dinner. The other half consumed 20% of their daily calories at breakfast, followed by 35% at lunch and 45% at dinner.
The groups then switched places, following the opposite regimen for another four weeks.
Both groups consumed slightly more than 1,700 calories per day. Big breakfasts consisted of foods like cereal, toast, eggs, sausage, smoothies and yogurt. Large dinners consisted of foods like beef and mushroom stroganoff with rice, pasta bolognese or pork chops with potatoes and peas.
Researchers don't often provide meals to study participants, so the study offers a rare look at how one factor — the timing of a person's largest daily meal — affects metabolism and weight loss.
In the end, the researchers added up how much total weight each group lost after four weeks of the big breakfast diet and the big dinner diet. The results came out the same: around 7 pounds.
That's clear evidence that people did not burn more calories by eating a big breakfast, according to Courtney Peterson, an associate professor of nutrition sciences at the University of Alabama at Birmingham who wasn’t involved in the research.
The results show that "there’s no magic fat-burning effect from the timing of your meals," Peterson said.
However, people in the study said they felt less hungry throughout the day when they consumed the bulk of their calories at breakfast. So it's possible that big breakfasts could help with weight loss over longer periods of time by decreasing appetite, Peterson said.
"There are two ways to lose weight: You can either burn more calories or you can eat less," she said. "In the real world, if people are less hungry, they eat less, so that usually translates into weight loss."
Alexandra Johnstone, the study’s senior author and a researcher at the University of Aberdeen in Scotland, said a big breakfast could also potentially "help people control appetite to stick to a calorie-counted diet."
Early meals could still have benefits
Unlike the UK study, other research has suggested that people who eat a large breakfast can see decreases in their body-mass index.
Martha Belury, a professor of human nutrition at Ohio State University, said the new study might have seen a greater weight loss effect if the researchers had given subjects more high-quality, nutrient-rich foods.
“Certain foods, if you have a mass of them or a tiny bit of them, they can stimulate more hunger than other types of foods,” she said.
But weight loss aside, there may be other good reasons to eat a substantial breakfast. Johnstone said that people are more insulin-sensitive in the morning, so an early meal might help regulate blood sugar levels. On the other hand, eating too late at night — from around 8 p.m. onward, Peterson said — could raise blood sugar levels and cause people to store more energy as fat.
Johnstone's study did not observe an improvement in blood sugar levels from big breakfasts. But a study of overweight or obese women in Israel saw improved blood sugar levels among those who ate a 700-calorie breakfast, followed by a 500-calorie lunch and 200-calorie dinner.
The new research also has implications for intermittent fasting, an eating schedule in which food intake is limited to a specific window — usually eight hours during the day.
"What this study would suggest is that when people are doing time-restricted feeding, it might be better to time restrict in the evening and eat during the morning to afternoon period," Johnstone said.
That's likely because people who fast in the morning feel hungrier in the afternoon and evening, so they reach for more calories than those who start eating earlier, Peterson said.
Like the big breakfast strategy, the relationship between intermittent fasting and weight loss is complicated.
"About half of studies find a weight loss effect and half don’t," Peterson said. "To me, that suggests there’s probably a benefit there, but we need to go to even larger studies to demonstrate that."
Belury said a person's meal routine should take into account the times of day when they burn the most energy and their individual response to food.
“There is quite a bit of personal preference in terms of eating patterns in general," she said. "Some people say, for whatever reason, they don’t like a big breakfast because they find if they have a big breakfast, then they still have a big lunch.”