In the world of weight loss, women are often told that when we choose to eat is just as important as what we choose to eat. This is because the body burns more calories at certain times of the day. The advice that follows this is typically: Eat a big breakfast to boost your metabolism. But is there any merit to the big breakfast theory? According to a recent study published in Cell Metabolism, not exactly.
Here’s the gist: Based on the results of this study, a big breakfast doesn’t change the way your body metabolizes calories. (In other words, consuming more calories in the morning won’t necessarily help you burn more calories throughout the day.) However, it may help you feel less hungry later in the day, and therefore less likely to snack at night — which could help you lose weight. Learn more about the research below.
Understanding the Research
The Cell Metabolism study was conducted by researchers at Scotland’s University of Aberdeen who wanted to better understand the effects of a big breakfast. To do so, they recruited 16 men and 14 women for a four-week trial. (This might sound like a small group of participants, but the study was a randomized crossover trial, which is a high standard in the scientific community.) All participants were overweight or obese — according to the definition set by the CDC — at the start of the trial. The average age was 51 years old.
For all four weeks, the researchers gave the participants the same prescribed diet. It was a little over 1700 calories per day and comprised 30 percent protein, 35 percent fat, and 35 percent carbohydrate. Then, participants were randomly assigned to two groups. For the first half of the study, group one ate a “morning-loaded” diet, or more calories before noon, and group two ate an “evening-loaded” diet. Next, there was a one week “washout period” wherein all participants consumed the same number of calories, and calories were distributed evenly between at every meal. Following the washout period, the groups swapped; group one ate an evening-loaded diet, while group two ate a morning-loaded diet.
The researchers carefully measured the participants’ energy and exercise levels, noting that the average daily steps, for all participants, was about 7,000 each week. The researchers also monitored sleep times, blood pressure, and blood glucose, insulin, and cholesterol levels.
Here’s what the researchers found: Eating a morning-loaded diet did not result in greater weight loss. At the end of each week, all participants lost a similar amount of weight. However, participants on the morning-loaded diet reported feeling significantly less hungry (and even less thirsty) than those on the evening-loaded diet. The reason? The researchers pointed out that bigger meals take longer to empty out of the stomach and the gut. This process suppresses the hunger hormone, ghrelin, and increases satiety hormones. So, participants on the morning-loaded diet benefited from feeling more satiated throughout the day, while those in the evening-loaded group didn’t feel satiated until dinner time.
“The participants reported that their appetites were better controlled on the days they ate a bigger breakfast and that they felt satiated throughout the rest of the day,” Professor Alexandra Johnstone, senior author and researcher at the University of Aberdeen, said in a press release. “This could be quite useful in the real-world environment, versus in the research setting that we were working in.”
Things To Keep in Mind
While this study was high quality, it has its limitations. Some participants ate food outside of the prescribed diet. In addition, many participants had leftovers. (People on the morning-loaded diet often couldn’t finish their breakfasts and lunches. The researchers, however, maintain that each participant generally ate the same amount of calories.) The study was also conducted under free-living conditions, meaning the researchers couldn’t control every aspect of each participant’s day.
Despite these caveats, this trial supports the theory that “a calorie is a calorie,” and your body will metabolize it the same way, no matter the time of day. Still, eating a bigger breakfast has its benefits, and may be a useful tool if you are trying to lose fat and gain muscle.
Not a big breakfast person? Start small. Nutritionists recommend making breakfast a habit even if you don’t eat much in the mornings, because it will give you more energy throughout the day. It might be the key to staying more consistent with a healthy diet.
This content is not a substitute for professional medical advice or diagnosis. Always consult your physician before pursuing any treatment plan.