Does it Matter What Time You Eat?

New research suggests eating earlier may help you lose weight. Nutrition Diva digs into the controversy.

Monica Reinagel, MS, LD/N, CNS
4-minute read
Episode #235

Nutrition Diva Monica Reinagel Talks about Eating Before Bed and Weight Loss

I’m sure you’ve heard the advice to “eat breakfast like a king, lunch like a prince, and dinner like a pauper.” Many people believe that it’s healthier to eat lightly in the evening. In fact, one popular weight loss trick is not to eat anything at all after 8pm, despite the fact that our appetite peaks in the evening..

See also: Are we hard-wired to snack in the evenings?

What’s the rationale for this?

People often imagine that if they do something physically active after a meal, they are using up the calories in the food they just consumed. By the same token, they believe that if they go to bed soon after eating dinner, the energy from the food they’ve just eaten will all be stored as fat. But that’s not really how it works.

You Can’t “Walk Off” a Big Meal

For one thing, it takes your body up to 2 hours to digest food and turn it into energy for biological functions. If you get up from the dinner table and take a 45-minute walk, you’re not using up the food you just ate—most of it won’t even have left your stomach yet. (Not to mention the fact that the average meal contains 500 to 800 calories and walking for 45 minutes will only burn off a hundred or so.)

Secondly, I think people vastly over-estimate what percentage of their daily energy (or calorie) expenditure goes to physical activity. Up to three quarters of the calories you burn every day are used simply to power basic metabolic functions like breathing, pumping blood, and all the various cellular activities involved in staying alive. These activities take place round the clock, including while you are sleeping. So the idea that you stop burning calories when you go to bed is ridiculous.

Thirdly, storing energy from food for future use is not necessarily a bad thing. In fact, the ability to extract energy from food and then store it until needed by our cells is really the whole point of our digestive system. Imagine, for a moment, what it would be like if food intake had to be timed with energy expenditure. It would be like needing someone to run alongside of your car and pour gasoline into the engine as you drove.

How Much You Eat is More Important than When You Eat It

Of course, we do need to match the amount of energy we take in to the amount of energy we use. If you consistently take in more than you use, the overage will accumulate as body fat. Fortunately, we don’t have to precisely synchronize the timing.

So, while I agree that cutting out after-dinner snacking can be an effective way to lose weight, it’s not because I think that food eaten late in the day is more likely to be stored as fat. Rather, it’s because after dinner snacking tends to provide a lot of unnecessary (and often empty) calories. I figure that if you’re eating the right amount of food for your body, it shouldn’t matter too much when you eat it.

Related: How Many Calories Do I Need?

New Research Suggests That Timing Matters

But a new study has thrown cold water on my theory. Or, at the very least, has significantly muddied the waters. This study tracked several hundred people taking part in a weight loss treatment program. The researchers found that those who ate the bulk of their calories in the second half of the day lost weight more slowly than those whose calorie intake occurred earlier in the day—even though both groups ate roughly the same types and amount of foods, and had similar exercise patterns. Even the researchers were surprised by these results.

It’s not surprising that the body’s metabolism would vary over the course of the day and night. After all, we have hormones that cycle up and down, our body temperature varies in a 24 hour cycle, and food may be processed more or less efficiently at various times of the day. But to be perfectly honest with you, I’ve never thought these fluctuations would be large enough to make a significant difference in terms of weight loss. I may have been wrong.

I still think that what you eat is more important than when you eat it. But timing may play more of a role than I’ve previously credited. Particularly if you’re actively trying to lose weight.

Eat Early to Lose More Weight

Of course, when it comes to our bodies, one size does not fit all—and if what you’re doing is working for you, there’s no need to change it. Let’s say you’re someone who eats a healthy diet but whose meal times tend to skew later in the day. If you are maintaining a healthy weight, or you’re making steady progress toward a healthy weight, and you’re comfortable with your current routine, I think you should stick to it.

If, on the other hand, you are working at weight loss and are frustrated by slow progress, I think it would be worth doing an experiment. Don’t change what you eat. Just redistribute your food intake so that more of the calories happen earlier in the day. Try a more Mediterranean approach and eat your largest meal at mid-day and eat a smaller meal at the end of the day. Do this for a couple of weeks and see if your body responds any differently. If changing up the timing of your meals seems to make a positive difference, I’d think you’d want to stick with that approach.

As always, I want to hear from you! What’s working for you and what’s not? What other nutrition topics would you like me to explore on the podcast. Post your comments and questions here or on my Nutrition Diva Facebook Page.

Woman Walking image from Shutterstock

About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.