Do you really have to give up carbohydrates to lose weight? If you’ve ever tried to eliminate bread, pasta, and potatoes, you know how much of a struggle it can be. The challenge gets even worse if you remove whole grains like quinoa and brown rice from your diet. If that step made you feel kind of miserable (we hear you!), it’s time to try a different tactic. Research shows that you can still eat high-carb foods and burn them off – you just have to eat them in the morning.
In a study from Current Biology, researchers found evidence that the body burns more carbs in the morning than it does in the evening. The theory comes from investigations of circadian rhythms and how irregular schedules can lead to weight gain. Circadian rhythms, or 24-hour cycles that regulate our sleep-wake cycle and other body processes, control way more than we thought!
Understanding the Experiment
For the study, the researchers recruited 13 participants and measured their circadian rhythms. They were curious to see whether circadian rhythms could control energy expenditure regardless of whether a person was asleep, awake, or eating. Resting energy expenditure, or resting metabolic rate, is the amount of energy a person uses to maintain essential body functions. Those include respiration, circulation, and digestion.
Studying circadian rhythms is a tricky business, because so many different outside factors can affect the outcome. Humans are naturally influenced by a light or dark sky and other markers of time passing. As a result, the researchers used an experimental protocol called forced desynchrony to eliminate those factors.
During this protocol, the team put participants on a specific schedule that controlled how much time they spent in the light and in the dark. The team also controlled how much rest and activity the participants had and how long the entire schedule was. In most forced desynchrony experiments, the schedule is shorter or longer than 24 hours. This allows a person’s internal clock to run free according to its own loose measure of time.
For this investigation, seven participants went on a 28-hour rest and activity schedule for three weeks. Six participants in the control group went on a regular 24-hour schedule for three weeks. The researchers also controlled the diets of both groups.
How Circadian Rhythms Affects Your Metabolism
Over the course of study, the team measured the resting metabolic rate of all the participants. The participants’ resting metabolisms burned 60 to 70 percent of all calories that they consumed in a day, which is typical. What was more interesting was when that resting metabolism increased or decreased.
To understand how the research team measured circadian rhythms, think of a circle. The top center of the circle is 0 degrees, which corresponds to biological night. The bottom center is 180 degrees, which corresponds to biological noon. As you may have expected, the resting metabolism was at its lowest when the participants’ circadian phase was at 0 degrees, or biological night. It was at its highest at 180 degrees, or biological noon.
“While awake and resting, the human body burns the fewest calories during the late biological night and the most calories during the biological afternoon and evening,” the study authors wrote. This can explain why it may be better to eat more calories from morning to noon and fewer calories as the day goes on.
But that wasn’t the end of the study. The researchers also analyzed the participants’ fasting carbohydrate oxidation, or the number of carbohydrates the participants’ burned during the day. They found that they burned the least number of carbs in the evening and the most in the morning.
The Reason Eating Carbohydrates in the Morning May Work
Why might we burn more carbs in the morning? One theory is that eating carbs early on gives the body time to use them before resting metabolism slows down for the evening. Celebrity trainer and author David Kirsch told Harper’s Bazaar that cutting off carbs after a certain time can help you lose weight and look slimmer.
“Eating carbs in the morning and throughout the middle of the day helps you fuel properly for the entire day,” he said. “Because carbs retain water in your body, you start looking fuller. Cutting your carb intake off at a certain point, such as 2:30, gives your body a chance to absorb and drain all of that excess water. It also gives you time to burn them off throughout the rest of the day.”
Others worry that eating a lot of carbs in the morning can cause a blood sugar spike and leave you feeling groggy. This is particularly true if you eat refined and processed carbs. But if you skip the bagel and opt for a bowl of hearty oatmeal – which contains a balance of carbs, protein, and fiber – you can avoid a groggy afternoon.
Whether you try cutting off carbs around noon or 2:30, it’s worth a shot! Just remember to balance out your high-carb foods with healthy fats, protein, and other nutrients. By adding carbohydrates back into your diet, you should feel more energized and satisfied.