morning meal weight loss

 A recent study investigated the effects of front-loading calories early in the day versus eating a big meal in the evening on weight loss and appetite.

The researchers found that larger meals in the morning are linked to lower appetite in the evening, but do not produce differences in weight loss compared to larger evening meals.

They noted, however, that having a big breakfast could help facilitate weight loss by reducing appetite.

Prior research has suggested that the time of day when large meals are consumed may influence weight loss.

One study from 2013Trusted Source shows that consuming a high calorie breakfast and reducing calories at dinner could promote weight loss in individuals with obesity and metabolic syndrome.

Another study from 2018Trusted Source shows that eating early in the morning reduces appetite in the evening, which could help facilitate weight loss.

But how both timing and distribution of caloric intake throughout the day impact weight loss have been relatively unexplored until now.

In a new study, researchers conducted a randomized controlled feeding trial comparing the effects of large morning meals with large evening meals. They found that both mealtimes resulted in similar weight loss outcomes. However, those who ate larger meals in the morning reported lower levels of hunger by the evening.

The results were published on September 9 in the journal Cell MetabolismTrusted Source.

Randomized controlled feeding trial 

For the study, researchers recruited 30 participants with clinical overweight or obesity but were otherwise healthy. They included 16 men and 14 women with an average age of 50.9.

Of the participants, 14 were randomized to eat a large morning meal diet (MM) first, while 16 received the large evening meal diet (EM) first.

After 4 weeks on one diet, participants underwent a series of tests and a “washout diet” before switching to the other diet for an additional 4 weeks.

Breakfast on the MM diet included 45% of the total daily caloric intake, while dinner included 20%. The inverse was true for the EM diet.

Bot intervention diets contained around 1,700 calories and similar levels of macronutrients. They comprised around 30% protein, 35% carbohydrate, and 35% fat.

Throughout the study, researchers recorded measures from the participants, including:

body weight

energy intake

physical activity

energy expenditure

energy metabolism

subjective appetite control

Throughout the study, the participants lost an average of over 3 kilograms each during the 4-week periods.

After analyzing the results, the researchers found that eating larger meals in the morning did not result in more weight loss or energy expenditure than those who ate larger meals in the evening.

They noted, however, that participants on the MM diet reported significantly lower hunger levels in the evening.

“[The researchers] were interested in testing the impact of meal distribution on energy expenditure, rather than finding out what would happen if they simply prescribed meals in a free-living situation for a period of time on appetite,” Leonie Heilbronn Ph.D., professor at the Faculty of Health and Medical Sciences at the University of Adelaide, Australia, not involved in the study, told Medical News Today.

“But what they found was that changes in appetite, not energy expenditure, are probably explaining the impacts that eating early are having [on body weight],” she noted.

Underlying mechanisms 

When asked what might explain why portion size in the morning might reduce hunger later in the day yet not affect weight loss, Prachi Singh, Ph.D., associate professor of clinical science at Louisiana State University, not involved in the study, told MNT:

“This may be related to the study design and the short study duration. The study required the participants to eat the same number of calories during the MM and EM diet plans. So irrespective of how hungry they felt, they tried to eat all the meals provided.”

“In real-life settings, it is likely that the effect of eating a large morning meal on hunger may result in lower calorie intake during the day and a larger weight loss than someone choosing to eat a big evening meal. More importantly, the reduction in hunger with MM diet plan is likely to make the calorie restriction sustainable and may help in weight loss maintenance.”

– Prachi Singh Ph.D., associate professor of clinical science at LSU

Alexandra Johnstone, Ph.D., RNutr, professor of Medical Sciences Nutrition at the University of Aberdeen, one of the study’s authors, noted that their results suggest that the appetite system may get attuned to food intake cues following an overnight fast.

This, she noted, might be linked to why a larger meal has a “positive impact on controlling appetite.” However, she said that further studies are needed to explore this.