Eating a big breakfast could help you burn double the amount of calories than if you eat a larger meal at dinner.
It could be the key to losing weight while also keeping blood sugar levels steady, researchers at Lübeck University in Germany said.
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Their study found filling up in the morning boosts a metabolism process known as diet-induced thermogenesis (DIT).
DIT refers to the number of calories the body expends to heat the body and digest food. It was shown to be twice as high for those who ate more at breakfast than at dinner.
On the other hand, a low-calorie breakfast increases appetite, especially for sweets, the researchers admitted.
The findings published in the Journal of Clinical Endocrinology and Metabolism were based on a laboratory experiment of 16 men.
They consumed a low and high calorie breakfast and dinner one day - and then vice versa on another.
DIT was 2.5 times higher when the high calorie meal was eaten in the morning than in the evening.
DIT is the body's way of heating in order to support digestion and transport of blood when eating. Different foods and meal times affect how many calories are used by the body to do it.
The study also showed increased blood sugar and insulin concentrations, caused by eating a meal, were diminished after breakfast, but not so much after dinner.
The results also showed eating a low-calorie breakfast caused sweet cravings with a higher appetite.
This suggests that those saving all their calories for the end of the day may face consequences because they snack more.
Corresponding author Dr Juliane Richter said: "Our results show 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.
"This finding is significant for all people as it underlines the value of eating enough at breakfast."
The study adds to increasing evidence that the best way of losing weight is to eat your largest meal in the morning - and your smallest in the evening.
Dr Richter, a neurobiologist at Lubeck University, said: "Eating more at breakfast instead of dinner could prevent obesity and high blood sugar."
Both obesity and high blood sugar can lead to a host of life-threatening illnesses, including cancer, cardiovascular disease and diabetes.
Previous research has shown that DIT is lower in people with obesity. It's seen as a measure of how well our metabolism is working.
DIT can differ depending on mealtime and is generally slower in the evening and at night, due to our body clocks.
Dr Richter said: "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."
Eating a large breakfast has long been thought to help prevent weight gain.
A 2017 study of over 50,000 adults, which found eating a big breakfast, medium lunch and small dinner led to lower BMIs (body mass indexes).
The US and Czech nutritionists tracked the participants for seven years and discovered eating the largest meal in the morning was among the most effective strategies for preventing long-term weight gain.
Professor Daniela Jakubowicz, author of The Big Breakfast Diet, found that those who piled on the calories in the morning were more likely to feel satisfied, preventing snacking throughout the day.
And another study by Professor Jakubowicz found that eating chocolate in the morning, when our metabolism is at its highest, prevented cravings for sweet things later on.