Breakfast, body weight and obesity

You’ve probably heard at some time the English saying “eat breakfast like a King, lunch like a prince and dinner like a pauper”. What’s more, you’d have a job finding someone who disagrees with the idea that breakfast is the most important meal of the day. Practically all dietary strategies for losing weight strongly recommend eating a hearty breakfast, on the premise that this first meal after getting up is the one that gives us the energy and nutrients to get through the day. Makes sense, doesn’t it? Those who defend this theory also say that this habit helps to regulate your appetite, to activate your metabolism and to avoid eating compulsively later in the day.

But is there any proof behind this theory? Let’s take a look at what science and studies say about it.

Several observational studies have backed up this recommendation over the years, particularly the findings from research studies which have revealed a correlation between skipping breakfast and being overweight. One such example is the results of the meta-analysis of several such studies published in 2011 under the title "Skipping breakfast and prevalence of overweight and obesity in Asian and Pacific regions: a meta-analysis", which effectively show that those people who skipped breakfast were relatively at greater risk of being overweight.

Another core argument used to back up this recommendation is that most people who manage to maintain their weight loss long term eat breakfast regularly. For example, the Weight Control Registry – a database of people who have lost 13 kilos or more for at least one year – points to the fact that 78% of those people eat breakfast every day.

However, every now and then, an observational study of this type sets alarm bells ringing by throwing up contradictory results. One such study was published not so long ago under the title "Experimental manipulation of breakfast in normal and overweight/obese participants is associated with changes to nutrient and energy intake consumption patterns" (2014). This small-scale research study analysed the nutritional profile of a group of 37 individuals and revealed that those who skipped breakfast did not have a greater calorie intake: just the opposite, in fact.

As most of you know only too well, hypotheses put forward on the basis of observational studies need to be confirmed using intervention trials, as correlation does not imply causality. So let’s focus on this second type of study for a more in-depth insight into the conclusions drawn and to check if they coincide with findings from observational studies.

There are, from what I can see in databases, two approaches to intervention trials on this issue. The first is based on specific analysis of the effect on people of skipping breakfast and focuses on how they fill their boots and their calorie intake in the next meal or hours immediately following this decision. The subject group is divided into two equal parts: one half is allowed to have breakfast whilst the other is not, and an analysis is subsequently made of the differences in appetite and calorie intake in subsequent meals throughout the day.

These are the findings I’ve found from this approach (study results on the effect of a particular food compared with another are not included here):

As can be seen, these three trials do not exactly give excessive support to the theory of “eat breakfast like a king”, as two of them actually concluded that at the end of the day, those who skipped breakfast had a lower total calorie intake.

But let’s continue with our investigation. As the studies cited above were of no more than a few hours duration (or one day at the most), weight loss between the two groups could not be compared. As some of you have no doubt already realised, the fact is that this type of study is not really comparable to what happens in real life, so the evidence they provide is somewhat limited. The studies of most interest for us would be those which divide the group into two on a random basis, giving one of the sub-groups the instruction to eat breakfast and the other not to and then to observe what happens over time, following a normal diet or a weight-loss diet.

As far as I’ve been able to ascertain, the first study which followed this approach, entitled "The role of breakfast in the treatment of obesity: a randomized clinical trial", was conducted in 1992. This study analysed the behaviour of 45 obese women subjected to a 12-week weight loss process, followed by a 6-month follow-up period. The group was divided into two sub-groups, one which had breakfast and one which didn’t, with both following isocaloric diets. At the end of the trial period, experts found no significant differences in weight between the two sub-groups, a logical finding since both diets contained the same amount of calories. What they did find, however, were differences in eating habits between the two sub-groups: the women who had breakfast ate less fat and more carbohydrates and were less inclined to binge eat.

These findings, though interesting, were not particularly enlightening, as they were hardly resounding and of little help in establishing solid guidelines regarding the effects of eating breakfast. This lack of evidence was clearly borne out through the review undertaken by U.S. scientists in 2013 entitled "Belief beyond the evidence: using the proposed effect of breakfast on obesity to show 2 practices that distort scientific evidence". In this review, the authors concluded that the belief that eating breakfast every day helps lose or maintain weight is, essentially, nothing more than that: a belief.

Fortunately, more light was shed on this subject relatively recently by the findings of a few important studies.

The first one, entitled "The effectiveness of breakfast recommendations on weight loss: a randomized controlled trial" (2014), is of great interest, as it analyses weight change in the course of a weight loss process following a relatively free diet, with and without breakfast. Over a period of 12 weeks, 283 participants were divided into 3 groups, all of which were given the same dietary guidelines to follow except with respect to eating breakfast. One group was asked not to eat breakfast, another to eat breakfast every day and the third was given no specific instructions regarding breakfast so as to act as a control group. The results were quite clear: no significant differences in weight loss were detected between those who ate breakfast and those who didn’t.

The second study, “Skipping breakfast leads to weight loss but also elevated cholesterol compared with consuming daily breakfasts of oat porridge or frosted cornflakes in overweight individuals: a randomised controlled trial” (2014), compared weight loss in 3 groups of dieting patients: one group eating cereals for breakfast, the second oatmeal porridge and the third, nothing but water. After one month, the third group, breakfasting exclusively on water, had lost most weight.

The third study, “The causal role of breakfast in energy balance and health: a randomized controlled trial in obese adults” (2016), compared weight loss between two groups with no eating restrictions other than that one was eating breakfast and the other wasn’t. No significant differences were identified between the two study groups.

And the fourth study, "The causal role of breakfast in energy balance and health: a randomized controlled trial in lean adults" (2014), was very different from the previous ones in its approach but highly complementary to it. The study analysed the effect of breakfast on the metabolism, the energy balance and other health indicators... in other words, the idea was to check the validity of the oft-heard claim that breakfast “normalises” the metabolism. To do so, 72 non-obese (normal weight) people were randomly divided into two groups and observed by experts over 6 months to compare the results.

As can clearly be seen in the graph below included in the research findings, the differences identified between the two groups did not give rise to different end results. In other words, the people who did not eat breakfast had a lower calorie intake but also expended less energy, whilst those who did eat breakfast had a higher calorie intake but also burnt more calories. In short, the end balance was the same in both cases.

Findings from a review of this issue were finally published in 2016 under the title “Evaluating the Intervention-Based Evidence Surrounding the Causal Role of Breakfast on Markers of Weight Management, with Specific Focus on Breakfast Composition and Size”. The authors’ conclusions were as follows:

"...there is limited evidence supporting the addition of breakfast for body weight management and daily food intake. Regarding the type of breakfast, accumulating evidence exists supporting the consumption of increased protein and fiber at breakfast, as well as consuming more energy during the morning hours. However, the majority of the studies that manipulated breakfast composition and content did not control for habitual breakfast behaviors; nor did those studies include a breakfast-skipping control. Thus, it is unclear whether the addition of these types of breakfast meals affects weight management".

On the subject of other health-related issues, study findings have shown that eating breakfast improves glucose control (particularly by minimising abrupt changes in glucose levels), especially amongst type 2 diabetes sufferers. Two studies, namely “High-energy breakfast with low-energy dinner decreases overall daily hyperglycaemia in type 2 diabetic patients: a randomised clinical trial” and “Fasting until noon triggers increased postprandial hyperglycemia and impaired insulin response after lunch and dinner in individuals with type 2 diabetes: a randomized clinical trial”, reached this conclusion in 2015. Furthermore, the above-mentioned 2016 study entitled “The causal role of breakfast in energy balance and health: a randomized controlled trial in obese adults” (2016), conducted in this case on people without diabetes, revealed a greater sensitivity to insulin amongst those who ate breakfast.

I don’t know what you think but I don’t believe there is much evidence to justify any specific recommendation regarding skipping breakfast or otherwise, especially for people in good health. Despite this, this issue is still generally considered a key dietary guideline.

1 comment:

  1. Anonymous7/20/2016

    Congratulations, very detailed review. But it's hard to fight against breakfast related myths.