Image Credit: Photo by Brooke Lark on Unsplash

Technology has made it easier than ever to sit for hours on the couch watching Netflix while browsing social media from the comforts of our smartphone. Unfortunately, this physically inactive lifestyle has led us to an energy imbalance in our bodies. We lose weight when we are in a negative energy balance–we burn more calories than we take in. In contrast, shifting to a positive energy balance–where we frequently eat high-calorie food with little exercise–leads to a higher risk of becoming overweight or obese. A common way people decide to lose weight is through dieting. Yet, there is currently no “miracle diet” that provides people with healthy weight-loss results. With this in mind, scientists are searching for different ways to produce a negative energy imbalance.

A recent research study found one way to increase a person’s energy expenditure by providing the ideal conditions for our metabolism to be most active. Researchers at the University of Lubeck in Germany studied different factors that could affect the rate our body burns food. The study looked at how our eating is influenced by circadian rhythms, a 24-hour clock inside of us managing our body. Circadian rhythms control our body patterns such as our sleep/wake cycle, digestive system, and light/dark cycle. A circadian rhythm disruption would be the feeling of “jet lag” after a trip from Japan to New York. Your body would need time to get used to waking up in New York when it would be the usual time you fall asleep in Japan. 

Since circadian rhythms play an important role in our lives, researchers looked to see if the amount of calories we eat (small meals vs. large meals) and the time we eat (morning vs. night) influences our metabolism. They predicted that these two factors could influence our metabolism, which would change how much calories a person expends.

The research study recruited sixteen normal-weight and healthy young men for a three day experiment. The men switched between a high-calorie breakfast and a low-calorie dinner, a low-calorie breakfast and high-calorie dinner, and vice versa. The amount of calories lost after breakfast and dinner was studied through a person’s diet-induced thermogenesis–a measure of how active our body is metabolizing food. Sleep, physical activity, and the amount of calories they ate in a meal was supervised and consistent with all the participants to reduce any bias of the study results. 

The researchers were able to show how our metabolism is influenced by our light/dark cycle. Eating breakfast made the men lose more than twice the number of calories than eating dinner. The men’s metabolism worked faster to convert the food into energy after breakfast regardless of calories. Expanding on these findings, the researchers also wanted to see how glucose metabolism was affected after breakfast and dinner. Glucose metabolism is when our body transforms sugar into energy and nutrients for the cells in our body. While blood sugar initially increased from eating breakfast, it lowered two and four hours after breakfast compared with dinner. The guys also showed less cravings for sweets after a high-calorie breakfast. 

This study provides dietary insight for people who are overweight or obese. People with obesity have an increased risk for Type 2 diabetes. This disease happens when the body is unable to respond to the insulin hormone that allows sugar to enter our cells. This causes our bodies to become more tired as our cells do not have the energy to sustain our internal processes. Blood sugar levels also remain higher than normal and can damage our blood vessels over time. This damage can lead to further health issues such as kidney disease, heart disease, and stroke. As the researchers saw greater metabolic activity and lower blood sugar levels in the morning, they predicted that people with or at-risk for obesity may benefit more from eating more food at breakfast than at dinner.

Study Information

Original study: Twice as High Diet-Induced Thermogenesis After Breakfast vs Dinner On High-Calorie as Well as Low-Calorie Meals

Study published on: February 19, 2020

Study author(s): Juliane Richter, Nina Herzog, Simon Janka, Thalke Baumann, Alina Kistenmacher, Kerstin M Oltmanns

The study was done at: Section of Psychoneurobiology, Center of Brain, Behavior and Metabolism, University of Lubeck, Lubeck, Germany

The study was funded by:

Raw data availability:

Featured image credit: Photo by Brooke Lark on Unsplash