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, published in Cell Metabolism, from the University of Aberdeen. The idea that ‘front-loading’ calories early in the day might help dieting attempts was based on the belief that consuming the bulk of daily calories in the morning optimizes weight loss by burning calories more efficiently and quickly.
“There are a lot of myths surrounding the timing of eating and how it might influence either body weight or health,” said senior author Alexandra Johnstone, PhD, a researcher at the Rowett Institute, University of Aberdeen, who specializes in appetite control. “This has been driven largely by the circadian rhythm field. But we in the nutrition field have wondered how this could be possible. Where would the energy go? We decided to take a closer look at how time of day interacts with metabolism.”
Her team undertook a randomized crossover trial of 30 overweight and obese subjects recruited via social media ads. Participants – 16 men and 14 women – had a mean age of 51 years, and body mass index of 27-42 kg/ m2 but were otherwise healthy. The researchers compared two calorie-restricted but isoenergetic weight loss diets: morning-loaded calories with 45% of intake at breakfast, 35% at lunch, and 20% at dinner, and evening-loaded calories with the inverse proportions of 20%, 35%, and 45% at breakfast, lunch, and dinner, respectively.
Each diet was followed for 4 weeks, with a controlled baseline diet in which calories were balanced throughout the day provided for 1 week at the outset and during a 1-week washout period between the two intervention diets. Each person’s calorie intake was fixed, referenced to their individual measured resting metabolic rate, to assess the effect on weight loss and energy expenditure of meal timing under isoenergetic intake. Both diets were designed to provide the same nutrient composition of 30% protein, 35% carbohydrate, and 35% fat.
All food and beverages were provided, “making this the most rigorously controlled study to assess timing of eating in humans to date,” the team said, “with the aim of accounting for all aspects of energy balance.”
No optimum time to eat for weight loss
Results showed that both diets resulted in significant weight reduction at the end of each dietary intervention period, with subjects losing an average of just over 3 kg during each of the 4-week periods. However, there was no difference in weight loss between the morning-loaded and evening-loaded diets.
The relative size of breakfast and dinner – whether a person eats the largest meal early or late in the day – does not have an impact on metabolism, the team said. This challenges previous studies that have suggested that “evening eaters” – now a majority of the U.K. population – have a greater likelihood of gaining weight and greater difficulty in losing it.
“Participants were provided with all their meals for 8 weeks and their energy expenditure and body composition monitored for changes, using gold standard techniques at the Rowett Institute,” Dr. Johnstone said. “The same number of calories was consumed by volunteers at different times of the day, with energy expenditure measures using analysis of urine.
“This study is important because it challenges the previously held belief that eating at different times of the day leads to differential energy expenditure. The research shows that under weight loss conditions there is no optimum time to eat in order to manage weight, and that change in body weight is determined by energy balance.”
Meal timing reduces hunger but does not affect weight loss
However, the research also revealed that when subjects consumed the morning-loaded (big breakfast) diet, they reported feeling significantly less hungry later in the day. “Morning-loaded intake may assist with compliance to weight loss regime, through a greater suppression of appetite,” the authors said, adding that this “could foster easier weight loss in the real world.”
“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,” Dr. Johnstone said.
“We know that appetite control is important to achieve weight loss, and our study suggests that those consuming the most calories in the morning felt less hungry, in contrast to when they consumed more calories in the evening period.
“This could be quite useful in the real-world environment, versus in the research setting that we were working in.”
‘Major finding’ for chrono-nutrition
Coauthor Jonathan Johnston, PhD, professor of chronobiology and integrative physiology at the University of Surrey, said: “This is a major finding for the field of meal timing (‘chrono-nutrition’) research. Many aspects of human biology change across the day and we are starting to understand how this interacts with food intake.
“Our new research shows that, in weight loss conditions, the size of breakfast and dinner regulates our appetite but not the total amount of energy that our bodies use,” Dr. Johnston said. “We plan to build upon this research to improve the health of the general population and specific groups, e.g, shift workers.”
It’s possible that shift workers could have different metabolic responses, due to the disruption of their circadian rhythms, the team said. Dr. Johnstone noted that this type of experiment could also be applied to the study of intermittent fasting (time-restricted eating), to help determine the best time of day for people to consume their calories.
“One thing that’s important to note is that when it comes to timing and dieting, there is not likely going to be one diet that fits all,” she concluded. “Figuring this out is going to be the future of diet studies, but it’s something that’s very difficult to measure.”
Great variability in individual responses to diets
Commenting on the study, Helena Gibson-Moore, RNutr (PH), nutrition scientist and spokesperson for the British Nutrition Foundation, said: “With about two in three adults in the UK either overweight or obese, it’s important that research continues to look into effective strategies for people to lose weight.” She described the study as “interesting,” and a challenge to previous research supporting “front-loading” calories earlier in the day as more effective for weight loss.
“However, whilst in this study there were no differences in weight loss, participants did report significantly lower hunger when eating a higher proportion of calories in the morning,” she said. “Therefore, for people who prefer having a big breakfast this may still be a useful way to help compliance to a weight loss regime through feeling less hungry in the evening, which in turn may lead to a reduced calorie intake later in the day.
“However, research has shown that as individuals we respond to diets in different ways. For example, a study comparing weight loss after a healthy low-fat diet vs. a healthy low-carbohydrate diet showed similar mean weight loss at 12 months, but there was large variability in the personal responses to each diet with some participants actually gaining weight.
“Differences in individual responses to dietary exposures has led to research into a personalized nutrition approach which requires collection of personal data and then provides individualized advice based on this.” Research has suggested that personalized dietary and physical activity advice was more effective than conventional generalized advice, she said.
“The bottom line for effective weight loss is that it is clear there is ‘no one size fits all’ approach and different weight loss strategies can work for different people but finding effective strategies for long-term sustainability of weight loss continues to be the major challenge. There are many factors that impact successful weight management and for some people it may not just be what we eat that is important, but also how and when we eat.”
This study was funded by the Medical Research Council and the Scottish Government, Rural and Environment Science and Analytical Services Division.
A version of this article first appeared on Medscape.co.uk.
, published in Cell Metabolism, from the University of Aberdeen. The idea that ‘front-loading’ calories early in the day might help dieting attempts was based on the belief that consuming the bulk of daily calories in the morning optimizes weight loss by burning calories more efficiently and quickly.
“There are a lot of myths surrounding the timing of eating and how it might influence either body weight or health,” said senior author Alexandra Johnstone, PhD, a researcher at the Rowett Institute, University of Aberdeen, who specializes in appetite control. “This has been driven largely by the circadian rhythm field. But we in the nutrition field have wondered how this could be possible. Where would the energy go? We decided to take a closer look at how time of day interacts with metabolism.”
Her team undertook a randomized crossover trial of 30 overweight and obese subjects recruited via social media ads. Participants – 16 men and 14 women – had a mean age of 51 years, and body mass index of 27-42 kg/ m2 but were otherwise healthy. The researchers compared two calorie-restricted but isoenergetic weight loss diets: morning-loaded calories with 45% of intake at breakfast, 35% at lunch, and 20% at dinner, and evening-loaded calories with the inverse proportions of 20%, 35%, and 45% at breakfast, lunch, and dinner, respectively.
Each diet was followed for 4 weeks, with a controlled baseline diet in which calories were balanced throughout the day provided for 1 week at the outset and during a 1-week washout period between the two intervention diets. Each person’s calorie intake was fixed, referenced to their individual measured resting metabolic rate, to assess the effect on weight loss and energy expenditure of meal timing under isoenergetic intake. Both diets were designed to provide the same nutrient composition of 30% protein, 35% carbohydrate, and 35% fat.
All food and beverages were provided, “making this the most rigorously controlled study to assess timing of eating in humans to date,” the team said, “with the aim of accounting for all aspects of energy balance.”
No optimum time to eat for weight loss
Results showed that both diets resulted in significant weight reduction at the end of each dietary intervention period, with subjects losing an average of just over 3 kg during each of the 4-week periods. However, there was no difference in weight loss between the morning-loaded and evening-loaded diets.
The relative size of breakfast and dinner – whether a person eats the largest meal early or late in the day – does not have an impact on metabolism, the team said. This challenges previous studies that have suggested that “evening eaters” – now a majority of the U.K. population – have a greater likelihood of gaining weight and greater difficulty in losing it.
“Participants were provided with all their meals for 8 weeks and their energy expenditure and body composition monitored for changes, using gold standard techniques at the Rowett Institute,” Dr. Johnstone said. “The same number of calories was consumed by volunteers at different times of the day, with energy expenditure measures using analysis of urine.
“This study is important because it challenges the previously held belief that eating at different times of the day leads to differential energy expenditure. The research shows that under weight loss conditions there is no optimum time to eat in order to manage weight, and that change in body weight is determined by energy balance.”
Meal timing reduces hunger but does not affect weight loss
However, the research also revealed that when subjects consumed the morning-loaded (big breakfast) diet, they reported feeling significantly less hungry later in the day. “Morning-loaded intake may assist with compliance to weight loss regime, through a greater suppression of appetite,” the authors said, adding that this “could foster easier weight loss in the real world.”
“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,” Dr. Johnstone said.
“We know that appetite control is important to achieve weight loss, and our study suggests that those consuming the most calories in the morning felt less hungry, in contrast to when they consumed more calories in the evening period.
“This could be quite useful in the real-world environment, versus in the research setting that we were working in.”
‘Major finding’ for chrono-nutrition
Coauthor Jonathan Johnston, PhD, professor of chronobiology and integrative physiology at the University of Surrey, said: “This is a major finding for the field of meal timing (‘chrono-nutrition’) research. Many aspects of human biology change across the day and we are starting to understand how this interacts with food intake.
“Our new research shows that, in weight loss conditions, the size of breakfast and dinner regulates our appetite but not the total amount of energy that our bodies use,” Dr. Johnston said. “We plan to build upon this research to improve the health of the general population and specific groups, e.g, shift workers.”
It’s possible that shift workers could have different metabolic responses, due to the disruption of their circadian rhythms, the team said. Dr. Johnstone noted that this type of experiment could also be applied to the study of intermittent fasting (time-restricted eating), to help determine the best time of day for people to consume their calories.
“One thing that’s important to note is that when it comes to timing and dieting, there is not likely going to be one diet that fits all,” she concluded. “Figuring this out is going to be the future of diet studies, but it’s something that’s very difficult to measure.”
Great variability in individual responses to diets
Commenting on the study, Helena Gibson-Moore, RNutr (PH), nutrition scientist and spokesperson for the British Nutrition Foundation, said: “With about two in three adults in the UK either overweight or obese, it’s important that research continues to look into effective strategies for people to lose weight.” She described the study as “interesting,” and a challenge to previous research supporting “front-loading” calories earlier in the day as more effective for weight loss.
“However, whilst in this study there were no differences in weight loss, participants did report significantly lower hunger when eating a higher proportion of calories in the morning,” she said. “Therefore, for people who prefer having a big breakfast this may still be a useful way to help compliance to a weight loss regime through feeling less hungry in the evening, which in turn may lead to a reduced calorie intake later in the day.
“However, research has shown that as individuals we respond to diets in different ways. For example, a study comparing weight loss after a healthy low-fat diet vs. a healthy low-carbohydrate diet showed similar mean weight loss at 12 months, but there was large variability in the personal responses to each diet with some participants actually gaining weight.
“Differences in individual responses to dietary exposures has led to research into a personalized nutrition approach which requires collection of personal data and then provides individualized advice based on this.” Research has suggested that personalized dietary and physical activity advice was more effective than conventional generalized advice, she said.
“The bottom line for effective weight loss is that it is clear there is ‘no one size fits all’ approach and different weight loss strategies can work for different people but finding effective strategies for long-term sustainability of weight loss continues to be the major challenge. There are many factors that impact successful weight management and for some people it may not just be what we eat that is important, but also how and when we eat.”
This study was funded by the Medical Research Council and the Scottish Government, Rural and Environment Science and Analytical Services Division.
A version of this article first appeared on Medscape.co.uk.
, published in Cell Metabolism, from the University of Aberdeen. The idea that ‘front-loading’ calories early in the day might help dieting attempts was based on the belief that consuming the bulk of daily calories in the morning optimizes weight loss by burning calories more efficiently and quickly.
“There are a lot of myths surrounding the timing of eating and how it might influence either body weight or health,” said senior author Alexandra Johnstone, PhD, a researcher at the Rowett Institute, University of Aberdeen, who specializes in appetite control. “This has been driven largely by the circadian rhythm field. But we in the nutrition field have wondered how this could be possible. Where would the energy go? We decided to take a closer look at how time of day interacts with metabolism.”
Her team undertook a randomized crossover trial of 30 overweight and obese subjects recruited via social media ads. Participants – 16 men and 14 women – had a mean age of 51 years, and body mass index of 27-42 kg/ m2 but were otherwise healthy. The researchers compared two calorie-restricted but isoenergetic weight loss diets: morning-loaded calories with 45% of intake at breakfast, 35% at lunch, and 20% at dinner, and evening-loaded calories with the inverse proportions of 20%, 35%, and 45% at breakfast, lunch, and dinner, respectively.
Each diet was followed for 4 weeks, with a controlled baseline diet in which calories were balanced throughout the day provided for 1 week at the outset and during a 1-week washout period between the two intervention diets. Each person’s calorie intake was fixed, referenced to their individual measured resting metabolic rate, to assess the effect on weight loss and energy expenditure of meal timing under isoenergetic intake. Both diets were designed to provide the same nutrient composition of 30% protein, 35% carbohydrate, and 35% fat.
All food and beverages were provided, “making this the most rigorously controlled study to assess timing of eating in humans to date,” the team said, “with the aim of accounting for all aspects of energy balance.”
No optimum time to eat for weight loss
Results showed that both diets resulted in significant weight reduction at the end of each dietary intervention period, with subjects losing an average of just over 3 kg during each of the 4-week periods. However, there was no difference in weight loss between the morning-loaded and evening-loaded diets.
The relative size of breakfast and dinner – whether a person eats the largest meal early or late in the day – does not have an impact on metabolism, the team said. This challenges previous studies that have suggested that “evening eaters” – now a majority of the U.K. population – have a greater likelihood of gaining weight and greater difficulty in losing it.
“Participants were provided with all their meals for 8 weeks and their energy expenditure and body composition monitored for changes, using gold standard techniques at the Rowett Institute,” Dr. Johnstone said. “The same number of calories was consumed by volunteers at different times of the day, with energy expenditure measures using analysis of urine.
“This study is important because it challenges the previously held belief that eating at different times of the day leads to differential energy expenditure. The research shows that under weight loss conditions there is no optimum time to eat in order to manage weight, and that change in body weight is determined by energy balance.”
Meal timing reduces hunger but does not affect weight loss
However, the research also revealed that when subjects consumed the morning-loaded (big breakfast) diet, they reported feeling significantly less hungry later in the day. “Morning-loaded intake may assist with compliance to weight loss regime, through a greater suppression of appetite,” the authors said, adding that this “could foster easier weight loss in the real world.”
“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,” Dr. Johnstone said.
“We know that appetite control is important to achieve weight loss, and our study suggests that those consuming the most calories in the morning felt less hungry, in contrast to when they consumed more calories in the evening period.
“This could be quite useful in the real-world environment, versus in the research setting that we were working in.”
‘Major finding’ for chrono-nutrition
Coauthor Jonathan Johnston, PhD, professor of chronobiology and integrative physiology at the University of Surrey, said: “This is a major finding for the field of meal timing (‘chrono-nutrition’) research. Many aspects of human biology change across the day and we are starting to understand how this interacts with food intake.
“Our new research shows that, in weight loss conditions, the size of breakfast and dinner regulates our appetite but not the total amount of energy that our bodies use,” Dr. Johnston said. “We plan to build upon this research to improve the health of the general population and specific groups, e.g, shift workers.”
It’s possible that shift workers could have different metabolic responses, due to the disruption of their circadian rhythms, the team said. Dr. Johnstone noted that this type of experiment could also be applied to the study of intermittent fasting (time-restricted eating), to help determine the best time of day for people to consume their calories.
“One thing that’s important to note is that when it comes to timing and dieting, there is not likely going to be one diet that fits all,” she concluded. “Figuring this out is going to be the future of diet studies, but it’s something that’s very difficult to measure.”
Great variability in individual responses to diets
Commenting on the study, Helena Gibson-Moore, RNutr (PH), nutrition scientist and spokesperson for the British Nutrition Foundation, said: “With about two in three adults in the UK either overweight or obese, it’s important that research continues to look into effective strategies for people to lose weight.” She described the study as “interesting,” and a challenge to previous research supporting “front-loading” calories earlier in the day as more effective for weight loss.
“However, whilst in this study there were no differences in weight loss, participants did report significantly lower hunger when eating a higher proportion of calories in the morning,” she said. “Therefore, for people who prefer having a big breakfast this may still be a useful way to help compliance to a weight loss regime through feeling less hungry in the evening, which in turn may lead to a reduced calorie intake later in the day.
“However, research has shown that as individuals we respond to diets in different ways. For example, a study comparing weight loss after a healthy low-fat diet vs. a healthy low-carbohydrate diet showed similar mean weight loss at 12 months, but there was large variability in the personal responses to each diet with some participants actually gaining weight.
“Differences in individual responses to dietary exposures has led to research into a personalized nutrition approach which requires collection of personal data and then provides individualized advice based on this.” Research has suggested that personalized dietary and physical activity advice was more effective than conventional generalized advice, she said.
“The bottom line for effective weight loss is that it is clear there is ‘no one size fits all’ approach and different weight loss strategies can work for different people but finding effective strategies for long-term sustainability of weight loss continues to be the major challenge. There are many factors that impact successful weight management and for some people it may not just be what we eat that is important, but also how and when we eat.”
This study was funded by the Medical Research Council and the Scottish Government, Rural and Environment Science and Analytical Services Division.
A version of this article first appeared on Medscape.co.uk.
FROM CELL METABOLISM