Monday January 17 2011
More calories at breakfast leads to more calories during the day
The key to dieting is “not a big breakfast”, reported the Daily Express. It said that researchers of a study on 300 people claimed: “people ate the same at lunch and dinner, regardless of what they had for breakfast”.
This news report is based on a study that compared how many calories 300 obese and normal-weight people ate throughout the day, for a 10-day period. The research paper has not yet been published in full, but there is a draft copy available from the publisher’s website. The analyses in the study are complex and there are some errors that should be ironed out before publication.
However, one finding is certain, that greater intake of calories at breakfast was linked to greater overall daily calorie intake. It seems sensible that people trying to lose weight should apply the same calorie caution to their breakfast as to other meals in the day and if a large number of calories are consumed at breakfast, other meals should be adjusted to compensate for this to keep within recommended limits.
A healthy breakfast is still important, and this study should not be interpreted to mean that people trying to lose weight should skip breakfast.
Where did the story come from?
The study was carried out by researchers from the Technical University of Munich. The authors do not report any external sources of funding. The study is not fully published yet, but has been accepted for publication in the Nutrition Journal.
The newspaper reports appear mostly to be based on a press release from the journal. The research paper has not yet been published in full, but there is a draft copy available from the publisher’s website. The analyses in this research are complex and there appear to be small errors in the results and interpretations that make a full appraisal difficult to carry out.
What kind of research was this?
The researchers say that previous studies have had conflicting results regarding whether a high energy (high calorie) breakfast will reduce a person’s overall calorie intake for the rest of the day. While some have suggested that a big meal in the morning reduces overall energy intake over the course of the day, others have shown no evidence of this. They say it is difficult to compare the studies with one another directly because of the different methods that have been used, so a new study that looks at the issue again would be helpful.
Previous research has tried to answer this question using one of two methods. The first method is to compare the number of calories consumed at breakfast with the number of calories consumed during other meals. The second is to assess calorie intake according to the ratio of breakfast to total daily energy in later meals (i.e. what proportion of the day’s energy was from breakfast).
The researchers say it is possible that these other studies have had contradictory results because they analyse their data using these two different methods.
This cross-sectional study enrolled 280 obese individuals and 100 normal-weight subjects to assess the link between the number of calories eaten at breakfast and the energy consumed during other meals of the day and overall.
What did the research involve?
The obese participants were recruited through the clinic at which they were being treated for their weight problem. The normal-weight controls were recruited through advertisements and selected to match the obese group on age and gender. All participants kept a food diary for 10 days. For the obese group, this was for the period prior to the start of their therapy. The participants were asked to record what they ate and drank for this 10-day period, how much they consumed and the time of day they consumed it.
The participants were asked to note clearly in the diary which meal they were consuming. Any foods eaten between breakfast and lunch were considered to be morning snacks, while foods eaten between lunch and dinner were evening snacks. The researchers then converted the food eaten at different meals to calories and assessed the effect of breakfast size on overall daily intake. This was done in two different ways, first by analysing the number of calories consumed at breakfast and, second, according to the ratio of energy from breakfast to total daily energy, i.e. what proportion of the day’s energy was from breakfast.
What were the basic results?
In both obese and normal-weight subjects, the more calories consumed at breakfast the larger the total daily calories consumed. This means that on days when a large number of calories were eaten at breakfast, the total daily calorie intake was high.
The researchers note that the foods associated with a bigger (higher calorie) breakfast were bread, eggs, cake, yoghurt, cheese, sausages, marmalade and butter.
How did the researchers interpret the results?
The researchers conclude that greater energy intake at breakfast is associated with greater energy intake for the whole day in normal weight and obese subjects. They say, therefore, that low energy intake at breakfast can be helpful to lower daily energy intake and improve the energy balance during treatment of obesity.
This cross-sectional study found that highly calorific breakfasts were linked with a greater overall intake of calories during the day. The author’s conclusion seems sensible. The research paper has not yet been published in full, and there are a number of complexities and some potential errors in the available draft, which makes a full appraisal difficult.
One finding is certain from their analyses, that greater calories at breakfast were linked to greater overall daily calorie intake. It seems sensible that if you are eating a calorie controlled diet, the same calorie caution should apply to breakfast as to other meals and if a large number of calories are consumed at breakfast then other meals should be adjusted to compensate for this to keep within recommended limits.
Studies of this design usually have other weaknesses, one of which is the use of food diaries. It is possible that the participants reported that they were eating more or less than they actually were. The researchers tried to address this by telling the participants at the beginning of the study that what they wrote in their diary would not affect what food they received during their treatment. Presumably, they hoped this would make participants more honest about what they were eating. They were also asked not to change their diets during the 10-day period.
Importantly, the study also says that on days where breakfast constituted a small proportion of the total daily intake, the overall intake was significantly greater. This suggests that skipping breakfast leads to higher overall energy intake than having some breakfast. This study is not advocating skipping breakfast entirely, but suggests that eating a healthy breakfast is a good way to balance energy intake.