What Happens to Your Metabolism When You Eat At Night?

There’s a long-held belief that eating at night is a bad habit that turns those late-night calories directly into fat. The theory is simple: the later in the day, the fewer calories we burn, which means your metabolism slows down. Add that to a slower metabolism when you sleep, and it’s easy to see why “don’t eat much after 7pm” became a common piece of diet advice.

There’s just one problem: these theories were based on animal models and shift workers. 

When you look at the research about eating at night, the fluctuations and impact on your metabolism are not what you think. In fact, there might be benefits to eating at night. There are studies showing people who eat most of their calories at night burn more fat.

In this episode of That’s Healthy, Right? we take a deeper look at understanding if when you eat affects how you gain weight and what benefits you might experience with some nighttime calories. We’ll explore if breakfast really is the most important meal, when calories are most likely to be stored as body fat, and the number one factor for successful weight loss.

Have a question you want to be considered for the show? To submit a question, email a voice recording that you can do here to info@bornfitness.com.

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We Have Been Asking the Wrong Question About Breakfast – That’s Healthy, Right? Podcast

Eating at Night Does Not Make You Fat – Born Fitness

The Health Impact of Nighttime Eating: Old and New Perspectives — Nutrients

Weight Loss Is Greater With Consumption of Large Morning Meals and Fat-Free Mass Is Preserved With Large Evening Meals in Women on a Controlled Weight Reduction Regimen — The Journal of Nutrition 

Greater Weight Loss and Hormonal Changes After 6 Months Diet With Carbohydrates Eaten Mostly at Dinner — Obesity 

Chronobiological Aspects of Weight Loss in Obesity: Effects of Different Meal Timing Regimens — Chronobiology International 

The Role of Breakfast in the Treatment of Obesity — American Journal of Clinical Nutrition 

Influence of Meal Time on Salivary Circadian Cortisol Rhythms and Weight Loss in Obese Women — Nutrition 

Pre-sleep protein in casein supplement or whole-food form has no impact on resting energy expenditure or hunger in women  — British Journal of Nutrition


Adam Bornstein: Does your metabolism really slow down the later it is at night?

You know, the whole idea that if you eat right before you go to bed because you’re not going to go ahead and do activity –  you’re going to sleep, your body’s going into that sleep mode – that all those calories are more likely to be stored as fat.

On the surface, all of this seems to make complete sense because, after all, when you eat calories during the day and you’re active, you would be seemingly putting those calories to work.

But this whole idea of late-night eating leading to more weight or fat gain is just a complete misunderstanding of how your body stores fat in the first place. And the best way we like to put this is, think about exercise.

If you were to do one workout, great workout, first thing in the morning, would that work out be more effective from a caloric standpoint than if you were to do it late at night? And the answer is no.

A great workout is a great workout. In the same way that a great meal or a bad meal is just one meal. And the damage that a meal can do is dependent on the calories in the meal, not when you eat.

And scientists from Israel actually went so far to try and prove this out, where they decided to compare what would happen when people would have their largest meal of the day at nighttime – so at 8:00 PM or later – compared to having the largest meal at breakfast, which has been really, I guess historically considered the time to have your bigger meal or a lot of people will say breakfast is the most important meal of the day.

What they found, to the surprise of a lot of people, is that the people who had their biggest meal at night had fewer hunger cravings, and they were more satisfied with their meals.

But more importantly, they’ve lost 10% more body fat.

Now, this isn’t to say that you must have your biggest meal of the day at night, but what it does show is that eating at night inherently does not mean that those calories are more likely to be stored as body fat.

And that all just becomes down to the way that we gain weight is dependent on the total number of calories you eat within a day, not when you eat those calories at the time of day.

So, eat at night, eat in the morning, in the middle of the day, the timing of your meals is completely up to you. You just have to make sure that one way or another you’re keeping your calories in check.