By Michael Ormsbee, PhD, Florida State University

Edited by Kate Findley and proofread by Angela Shoemaker, The Great Courses Daily

Conventional wisdom states that nighttime eating is bad for you, but is this really the case? Professor Ormsbee examines the evidence. Also, should athletes eat protein before bed?

How Nighttime Eating Got Its Bad Rap

We’ve all heard that nighttime eating is bad for us. A study of mice seemed to support this theory.

In the study, if you changed the feeding time of mice so that they are fed a high-fat diet during the time when they normally sleep—which in mice is during the daylight hours—as opposed to nighttime, when they are normally awake—the mice gained more fat.

This was an interesting finding, but does this hold true for humans? Much of the scientific evidence that is cited for why we shouldn’t eat at night was based primarily on people who work the night-shift. The study participants were people who had jobs that provide 24-hour service, such as hospitals, and people suffering from night eating syndrome (NES)—an eating disorder characterized by eating more than half of your daily food intake after dinner, waking up from sleep to eat, and having little appetite for breakfast.

Night-shift workers and people with NES who ate late at night ended up getting bigger, fatter, and less healthy. In addition to late night eating, these individuals also have disturbed or restricted sleep, and the less sleep you get, the greater your chances for being overweight and obese. 

To mention the obvious response to sleeping less at night—more opportunity to eat—you have more hours in the day when you might eat, and this could obviously lead to trouble if you’re trying to achieve your optimal body composition. There is also controversy with what defines nighttime eating. 

Much of the research on this topic uses different criteria for night eating. Some will say that it’s the total calories consumed within a specified time frame—for example, calories consumed between 5:00 pm and midnight. 

Others will say it is waking up throughout the night to eat. The typical dinner meal may or may not be included in what is defined as nighttime eating.

What is not controversial is the take-away message that if you consume the majority of your food in the evening and during night hours, as opposed to during daytime hours, and eating in excess of your energy needs, then you will likely have some unfavorable changes in your body composition. Let’s be realistic, though. 

Redefining Nighttime Eating

Many of us eat our food at various intervals throughout the day and not primarily at one point in the day or another. Also, most people actually sleep during the night and work during the day. 

“Thus, the way that my research group defines nighttime eating, or pre-sleep eating, is simply taking in an additional snack after dinner and before going to bed,” Professor Ormsbee said.

It may just be a matter of knowing what our best food choices are if we want to eat at night. We know that large portions are not ideal, but what about low-calorie, nutrient-dense options? Many athletes and bodybuilders typically consume protein before bed, but are they reaping any benefits?

“In this field of performance nutrition and exercise physiology, we think about feeding our bodies all the time,” Professor Ormsbee said. “We basically know how to feed ourselves throughout the day, and in relation to exercise, in order to optimize body composition and health.” 

This is not surprising as much of the available research is tailored towards this optimization. For very active people, the rationale for consuming protein before bed is the belief that it would keep you anabolic overnight or promote muscle growth and repair. The idea is that over the long term, this continual anabolic state could lead to increased muscle recovery and performance. 

Protein Bedtime Snacks

Whey protein is a common supplement used every day by athletes and gym-goers. However, casein protein, which makes up 80% of the protein in milk, has been highlighted as the best to consume before sleep due to its slow release from the stomach. 

Casein is found in higher concentrations in foods like cottage cheese and Greek yogurt. The theory is that this allows for prolonged anabolism or, at least, less muscle breakdown overnight while you’re sleeping.

It wasn’t until 2012 that research-based evidence on the impact of consuming casein protein before bed was available. Professor Luc Van Loon and his research team in the Netherlands were the first to show us that consuming casein protein before bed increases muscle protein synthesis overnight. 

Specifically, they compared physically active young men who consumed either 40 g of casein protein equaling 160 calories or a placebo drink 2 ½ hours after a lower body resistance exercise workout, but within 30 minutes of going to bed. It turned out that the group who drank the casein protein had greater overnight muscle protein synthesis compared to drinking no protein.

They then completed a similar study in elderly men showing that casein protein at night before sleep—but this time via nasogastric tubing, so not exactly drinking it—had the exact same outcome. These studies demonstrated that we can digest and absorb protein at night and we can actually increase muscle protein synthesis while sleeping. 

Michael Ormsbee is an Associate Professor in the Department of Nutrition, Food, and Exercise Sciences and Interim Director of the Institute of Sports Sciences and Medicine in the College of Human Sciences at Florida State University. He received his MS in Exercise Physiology from South Dakota State University and his PhD in Bioenergetics from East Carolina University.

This article was edited by Kate Findley, Writer for The Great Courses Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for The Great Courses Daily.