It’s Total Calories, Not When You Eat

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Experts say it’s the total calories you consume per day that matter the most. Cavan Images/Getty Images
  • Researchers compared weight-loss diets that included either a large breakfast or a large dinner.
  • Both types of diets led to similar weight loss and metabolic reactions.
  • Those who had a larger breakfast felt fuller throughout the day, possibly making it easier to maintain the diet for longer.

Should you eat your biggest meal in the morning or in the evening?

Some researchers are saying it doesn’t make a lot of difference — as long as you consume the same number of calories throughout the day.

In a study published today in the journal Cell Metabolism, European researchers tested two types of weight-loss diets against each other.

Both diets included the same total number of calories each day.

But one diet had participants consume most of these calories in the morning, while the second had most of the calories in the evening.

The result? Both diets performed about the same in terms of weight loss.

The group who ate the larger morning meal, however, was significantly less hungry throughout the day.

In this study, 30 people, 16 men and 14 women, were recruited to participate, all of whom were either overweight or had obesity but were otherwise healthy.

No participants had diabetes, a condition that could significantly alter the results in a study of this size.

This was a real-world study, not restricted to a lab setting, with participants under observation for four weeks.

Each individual had a fixed daily calorie intake, but some had a larger morning meal while others had a larger evening meal.

How large is large? 45% of their daily calorie intake.

Lunches for both groups made up 35% of their calories while their smaller meal was 20%.

All participants got about 30% of their calories from proteins and 35% each from carbohydrates and fats.

At the end of the study, the weight-loss results for each group were comparable.

However, the group that had larger morning meals showed a decrease in ghrelin — a hormone that makes you feel hungry — during the day, while they also had an increase in hormones that make you feel full.

These participants also had slower gastric emptying, which means that their food spent more time in their stomachs before entering the rest of the digestive tract.

Researchers said this was an important finding because previous studies have suggested that front-loading your calories in the morning leads to enhanced weight loss.

Emily Feivor, RD, a registered dietitian at Long Island Jewish Forest Hills in Queens, part of Northwell Health in New York, told Healthline she wasn’t surprised by these results.

“The idea of keeping hunger in check with balanced meals at structured mealtimes may be a significant help in achieving appropriate portion sizes and intakes throughout the day, which is the most effective and simplest diet ‘secret’,” Feivor said.

Lori Welstead, MS, RD, LDN, a registered dietitian and nutritionist at the Section of Gastroenterology, Hepatology, and Nutrition at UChicago Medicine, told Healthline, “It is a challenge to study nutrition and metabolism in human subjects. We are not as simple as mouse models or as it may seem in the lab.”

“This was the first study of its kind and helps to build insight to provide the groundwork for more studies,” Welstead added.

She noted that the researchers admittedly couldn’t measure things such as glucose in the group that ate larger evening meals because the participants had to go to sleep.

Megan Wroe, MS, RD, CNE, CLEC, a wellness manager and registered dietitian for the Wellness Center at Providence St. Jude Medical Center in Fullerton, California, told Healthline she agreed that this study led to interesting questions for future research.

“I would love to see the authors take this study further now and assess outcomes of breakfast meals with various macronutrient composition. A high fat vs. high protein vs. high carb breakfast may instigate very different outcomes,” Wroe said.

It’s one thing to study weight-loss diets. It’s another to be on one.

While having a larger breakfast may make it easier to maintain a specific diet, it’s important to remember that in this study total daily calories were strictly controlled.

Experts say having a large breakfast without making any other lifestyle changes is unlikely to have a significant positive effect on your health.

“Breakfast should include the basic building blocks: high fiber from fruits/vegetables or whole grains plus a good amount of protein and some heart-healthy fats,” said Feivor.

“Beware of breakfast traps of high sugar/low fiber cereals, fruit juices (even 100%), pastries, and highly processed meats,” she warned.

“Listen to your body. If you are hungry then eat. If you are full then stop. It takes about 20 minutes to really notice that signal,” said Welstead.

“Many diets for weight loss are not geared toward sustainable lifestyle changes and are quick fixes. If it seems too good to be true, it probably is,” Welstead added.

The importance of physical activity can’t be ignored either.

“Improved heart rate, increased energy, and mood, reduced levels of stress, increased muscle tone, reduced visceral fat, and improved metabolic markers such as blood sugar and blood pressure are all common potential benefits of increased physical activity even if there is no weight loss associated with it,” said Wroe.

“Weight-loss diets almost never create sustained loss if there is no change in how the person eats. There is only so far calorie restriction can go, independent of when those calories are allotted into the day,” she added.

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