The Calorie Counter

Eat More Calories in the Morning than the Evening

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Why are calories eaten in the morning apparently less fattening than calories eaten in the evening?

One reason is that more calories are burned off in the morning due to diet-induced thermogenesis. That’s the amount of energy the body takes to digest and process a meal, given off in part as waste heat.

If you give people the exact same meal in the morning, afternoon, and night, their body uses up about 25% more calories to process it in the afternoon than night, and about 50% more calories to digest it in the morning. That leaves fewer net calories in the morning to be stored as fat.

Let’s put some actual numbers to it. A group of Italian researchers randomised 20 people to eat the same standardised meal at 8am or at 8pm, and then a week later had them all come back in to do the opposite. So, each person had a chance to eat the same meal for breakfast and for dinner.

After each meal, the subjects were place in a calorimeter contraption to precisely measure how many calories they were burning over the next three hours. The researchers calculated that the meal given in the morning took about 300 calories to digest, whereas the same meal given at night used up only about 200 calories to process. The meal was about 1,200 calories, but given in the morning, it ended up only providing about 900 calories, compared to more like 1,000 calories at night.