By Michael Ormsbee, PhD, Florida State University

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

Those who struggle with their weight might avoid eating before bed, thinking that it will cause more weight gain. According to Professor Ormsbee, though, eating the right kind of snack might actually lead to improved body composition.

Comparing Bedtime Snacks

One study found that when obese individuals consumed a low-calorie, protein plus carbohydrate cereal snack before bedtime over the course of four weeks, they consumed less calories overall and lost weight as a result. Professor Ormsbee’s team wondered what would happen if the nighttime snack was replaced by a low-calorie protein beverage.

Would appetite change? Would body composition improve?

What about any cardiometabolic issues or benefits associated with consuming protein or other foods before bed? In their study, they gave one of three beverages—casein protein, whey protein, or a carbohydrate drink—to overweight and obese people within 30 minutes of going to bed.

Ormsbee’s team found that the research participants ended up feeling fuller and had less desire to eat the next morning regardless of what they consumed—protein or carbohydrates, it didn’t matter. Their first thought was that this might be beneficial in terms of reducing total calorie intake the next day—similar to the cereal study. 

However, because the study was only one night long, and they didn’t measure how much food participants ate for breakfast, or if they ate less overall as a result of nighttime eating, they couldn’t determine whether the pre-sleep snacks had an impact on total calorie intake—they simply reported feeling more full and having less desire to eat.

Unfortunately, they also found that all groups, regardless of what they consumed, had higher insulin levels the next morning compared to normal. This was not an ideal finding because obesity is already associated with insulin resistance, or a lowered ability to use the insulin that is produced. 

Insulin Resistance for Obese Individuals

The solution to this problem is exercise, as exercise training increases insulin sensitivity. Professor Ormsbee’s team confirmed that adding daily exercise over a long period may stop or reverse this acute insulin resistance associated with eating bedtime snacks in overweight and obese people. 

When they carried out nighttime feeding of protein or carbohydrates before bed with their subjects for four weeks straight and included three days per week of exercise training, insulin levels did not change from baseline. 

Subjects could have their bedtime snack and feel fuller—an advantage when you’re trying to lower calorie intake—and with added exercise, their insulin levels remained stable. The study also showed that the group consuming the casein beverage felt fuller at the end of the four weeks compared to the groups consuming whey and carbohydrates. 

You might be wondering if there were any changes in body composition with the addition of exercise. Did the protein groups have a better outcome?

Exercise Outcomes for Protein Group

The study did show slight decreases in body fat and slight increases in lean mass in all groups, while body weight stayed the same. Additionally, metabolic rate was increased for the protein groups but decreased for the carbohydrate group. 

This was not large enough to be considered statistically significant, but the magnitude of change was interesting to the researchers. Because all the groups improved body composition, regardless of what they ate before bed, it was the exercise that was most important in body composition change, and not necessarily the impact of that before-bed protein on appetite.

However, the greater message might be that despite having an approximately 150-calorie snack—in this case from protein or a carbohydrate shake before bed—body composition still improved with exercise training. The women in the study did not gain weight or fat.

In a different study, they also found improvements in cardiovascular health as a result of exercise and drinking protein snacks before bedtime in overweight and obese women. Therefore, there may be some real advantages to consuming small protein snacks late at night.

We also know that increasing protein in your diet is advantageous for body composition over the longer studies. This nighttime addition of protein will help to increase total protein intake in your entire day. 

Fat Breakdown and Bedtime Snacks

What actually happens to fat during the overnight period in response to protein before bed? In 2016, Professor Ormsbee’s team published a study looking at how casein before bed influences overnight lipolysis or fat breakdown and mobilization in belly fat. The study found that casein may be consumed before sleep without impeding overnight or morning fat metabolism in young, obese men.

“What I want you to understand is that a broad statement like ‘don’t eat after 7 pm’ is outdated and based upon research that may not even apply to people like you,” Professor Ormsbee said. 

Large, high-calorie meals eaten late at night don’t seem to be tolerated as well as the same meal eaten earlier in the day. However, emerging research shows that small, high-protein beverages consumed before sleep may have a number of advantages—particularly when paired with dynamic exercise training. These advantages include improved muscle protein synthesis, increased muscle mass, increased strength, increased metabolism, and reduced desire to eat.

There is no need to fear eating at night, but the right choices need to be made to ward off fat gain and weight gain. For now, it looks like casein is the protein of choice for presleep consumption—and only 150 calories.

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.

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.