Meal Timing Study Says Don’t Eat at Night?

by Matt Weik

With broscience running all over the fitness industry, we came to find out that meal timing and frequency really means nothing these days. You have people following IIFYM (if it fits your macros) as well as the intermittent fasting crowd. Both of which, I am a huge fan of. However, it appears that new research is telling everyone to pump the brakes if you were considering eating a late-night snack or extending your meals late into the night.

Resist the Urge

It comes as no surprise that American’s love to divulge in treats at night, especially while watching hours of their favorite non-educational shows like the Bachelorette or the Kardashian’s. But now researchers are telling you to at least refrain from one of them in a new study (I’d tell you to give up both)—and that’s eating late at night.

This new study published by the Perelman School of Medicine at the University of Pennsylvania is saying eating late at night can increase weight, slow down fat metabolism, increase cholesterol levels as well as insulin, can increase your risk for diabetes and heart disease, as well as other health problems.

How It All Went Down (Literally)

For this particular study, the researchers used nine health adults. Each of the nine participants were to follow two separate eating schedules. Before the study began researchers drew blood from the adults to get baseline values. Then again, they were tested after their first completed eating schedule which was 8 weeks, and then again after their next 8 week eating schedule. There was a two-week gap between the eating schedules to allow their bodies to return to baseline before starting the next schedule (which they also had their blood drawn after the two-week break).

For the first schedule, all participants were asked to eat three meals and two snacks between 8am and 7pm. They were also asked to sleep between 11pm and 9am. After the eight weeks, they had blood drawn. This was then followed up by the two-week rest period.

For the second piece of the study, the participants were asked to again eat three meals and two snacks, but this time between noon and 11pm. The sleep cycle was consistent with first trial. Again, following the eight weeks, blood was drawn. All blood samples were analyzed and looked at weight, metabolism, and energy used.

What Did They Find?

Spoiler Alert! As the title reads, when the group consumed calories later at night, they were found over the eight weeks to put on body weight compared to the group who stopped eating at 7pm. They found the body did not metabolize food the same as it did during the day, as well as negative influences on insulin, glucose, cholesterol, and triglycerides. Overall, nothing positive came from continuing to eat later in the day.

Interestingly enough, they also noticed that when the group ate the bulk of their food during the day versus at night, they felt satiated longer into the night which kept them from wanting to binge. They believe it has to do with decreased ghrelin levels, which makes you hungry, as well as an increase in leptin, giving you the feeling of being satiated. Researchers believe that by training your body to get its food and fuel during the day will train it to release different hormones throughout the day to prevent the feeling of hunger during the night. This is a good thing, as when people consume calories at night, they are generally foods high in carbohydrates and/or fats.

One researcher said, “While lifestyle change is never easy, these findings suggest that eating earlier in the day may be worth the effort to help prevent these detrimental chronic health effects. We have an extensive knowledge of how overeating affects health and body weight, but now we have a better understanding of how our body processes foods at different times of day over a long period of time.”

Putting It All Together

Eating and snacking at night can have negative health consequences. Fulfilling your daily caloric needs earlier in the day and stopping the consumption of calories after 7pm seems like the best plan of attack. Sleep also seems to play a role in all of this as the group was able to get around 10 hours of sleep each night. It would be good to know what the findings would be if participants were only getting seven or eight hours of sleep each night as I feel 10 hours is a little unrealistic for most American’s.

Something else to consider is that the group who ate during the day, rather than into the night, stopped eating at 7pm. There are many IIFYM followers out there who consume their calories up until that time (or around there). How would IIFYM compare to this technique where people ate between 8am and 7pm? I think there’s a lot of different studies that can branch off of this one to give us a better idea of how the body works and how eating windows can affect overall health. It would also be beneficial to get more than nine participants in the study to get not only larger numbers, but more diverse of a group. But in the end, this particular study is telling us to stop eating late at night. So, if you’re one of the people who fits the description of sitting down with a bunch of snacks at night watching television, think about what was found in this research and consider how your health has changed over the years. Are you carrying more weight now than you were prior? How’s your health been in comparison? Skip the snacks late at night and you could regain your health and lean physique.


1.) Materials provided by University of Pennsylvania School of Medicine.

2.) University of Pennsylvania School of Medicine. “Timing meals later at night can cause weight gain and impair fat metabolism: Findings provide first experimental evidence of prolonged delayed eating versus daytime eating, showing that delayed eating can also raise insulin, fasting glucose, cholesterol, and triglyceride levels.” ScienceDaily. ScienceDaily, 2 June 2017. .