Wednesday, May 21, 2014

Breakfast!? An (Un-)Biased (?) Look at the Contemporary Scientific Evidence For and Against the Benefits of Having Breakfast and The Negative Effects of Skipping Meals

Believe it or not, but the question "low or high carb for breakfast" is non-sense, because there is no general answer. It depends on who is asking and what he is going to spend the rest of his day.
Before we can start reviewing the contemporary literature, we will have to define the term "breakfast" as the first meal in the day which is eaten in the AM. This definition differs from the "literal" one, I've used in a previous article with the title "Circadian Rhythmicity - "Breakfast" or "Breaking the Fast"? Fasting as Zeitgeber & All About King, Prince & Pauper" (read it) and is thus in line with the mainstream idea of standing up, showering and... yes, you got it: having breakfast.

If you google "breakfast" and "obesity" you're served a colorful potpourri of "pro breakfast" articles which will inform you about "facts" like "Eating a big breakfast fights obesity and disease" (ScienceDaily), or "Breakfast Combats Obesity and Diabetes in Young People" (medscape).
Learn more about fasting and eating / skipping breakfast at the SuppVersity

Breakfast and Circadian Rhythm

Does Meal Timing Matter?

Breakfast & Glucose Metab.

Breaking the Fast, Cardio & the Brain

Does the Break- Fast-Myth Break?

Fasting = Muscle- Loss - Always?
Could all these "experts" be wrong? For the obedient average Joe this sounds crazy. Like one of those theories from your average Internet conspiracy theorist, but if you look at the actual evidence you have to admit:"A definitive conclusion can be made concerning the role of breakfast skipping in weight change." (McCrory. 2014)

The reasons for our cluelessness are manifold

There is for example a very good reason I anteceded this article with a definition of "breakfast". The latter is after all something you won't find in the average study, which could therefore consider eating a donut at 11am in as much as "breakfast", as it would discard having a protein shake immediately after you wake up as "not breakfast".

If we look at the actual "average Joe" (according to US National survey data), we're getting into even more trouble. This guy was eating 2.76 meals in 1971–75, while he is now up to 2.96 in 1999–2002 (Kant. 2007).

In other words: Americans eat more frequently these days, but are still fatter

Obviously frequency alone doesn't tell us whether one of those "almost three" meals was actually the holy breakfast. I mean, if it wasn't it's obvious the Americans became fatter and fatter - right (sarcasm)? The data we are interested in, is thus not the total number of meal (if you want to know more about that, take a look at "Many Small Meals Suck!" | go for it!). The data we are interested in is the data in Figure 1, the number of non-obedient US citizens who don't listen to the well-meant advice from the USDA and simply skip one of their holy meals.
Figure 1: Prevalence of skipping meals (breakfast, lunch, dinner) and snacking in the US, 2009–10 (McCory. 2014).
As McCorey highlights in a recent review (2014), their number rose. This seems to be a contradiction. I mean, if the number of meal skippers increases, shouldn't the number of meal (on average) decrease, when it in fact rose from 11% to 18%? Well, it should, if it was not for the snackers and grazers who either skip breakfast and snack all-day or are over-obediently grazin' on 20+ small meals per day.

Figure 2: Prevalence of breakfast skipping among US men and women (USDA)
What's interesting, is that we will find that the was a decrease in breakfast skippin' from 2002 to 2009, of which I am pretty sure that it was (at least partly) mediated by headlines like the ones I quoted in the introduction to this article (USDA)

USDA shows a slight decrease in the prevalence of breakfast skippingin both men and women by about 4%. If not having breakfast was the root cause of the obesity epidemic, the average American should thus have lost a few pounds over the past decade - right?

Right! This should be the case if breakfast was the mythical "lean-maker" the "experts" want us to believe. The figures, i.e. the constantly increasing rate of obesity, don't disprove that (those who don't eat breakfast could simply gain even more weight), but they certainly put another "?" behind the statement that having breakfast has anti-obesogenic effects.

23% of males and 20% of females skip lunch!

Apropos "?", I am missing one, here! One behind the consequences of skipping lunch. With all the upheaval about skipping breakfast, people seem to have forgotten that lunch, not breakfast, was the most commonly skipped meal among most age groups in 2009–10. In most age groups, 23% of males and 20% of females are skipping this important (?) meal... and are - you bet - having an unhealthy snack later in the afternoon.
How careless is it not to have breakfast :-) According to the latest meta-analysis of cross-sectional studies (epidemiology) with the telling title "Belief beyond the evidence: using the proposed effect of breakfast on obesity to show 2 practices that distort scientific evidence." skipping breakfast is associated with a +55% increased obesity risk. A risk increase without any evidence of a causal relationship between the two epidemiologically assessed parameters.
Anyway! This is the breakfast skipping research summary and no afford to dig up the two or three studies that dealt with skipping lunch explicitly. Let's thus, just for the time being, assume breakfast does in fact keep you lean. How on earth would eating some extra-food do that, when we all agree that the root cause of the obesity epidemic is after all the ravenousness of the average Westerner and the ways in which his / her diet multiplies these effects...oh, I guess the latter will lead us right to one of the answer to our question.

Proposed reasons for the anti-obesity effects of breakfast

I am not sure if I will be able to list all of them, but the following list of explanations that have been brought forward to explain the cross-sectionally observed negative association between body weight and breakfast eating is probably pretty comprehensive:
  • skipping breakfast leads to lower satiety than if breakfast had been eaten, thus 
  • overeating will ensue later in the day, which
  • over time would result in weight gain
What? Yeah, in the end, this is all the "breakfastpromoters" have to tell you: It's an overcompensation for the energy missed at breakfast they blame the alleged fattening effects of not having breakfast on. As McCroy points out, in what's probably the most recent peer-reviewed analysis of the contemporary evidence, one could easily imagine another scenario
"in which breakfast skipping could result in no weight change over time, if breakfast skipping does not lead to overeating (i.e., if there is perfect compensation for the missed meal), or to weight loss if there is lack of compensation." (McCrory. 2014)
In his review McCory provides an enlightening overview of each of these possible scenarios, I don't want to keep from you. The“control” in this imaginary case study is a habitual breakfast eater with energy needs of 2000kcal/day, whose energy intake distribution across breakfast, lunch, snacks and dinner is 2000 kcal/day and therefore who is maintaining body weight.
Figure 3: Theoretical models illustrating different types of breakfast skippers vs. a habitual breakfast eater (McCrory. 2014).
There are potentially three types of habitual breakfast skippers: those with perfect compensation and maintain body weight, those who overcompensate and gain weight, and those who undercompensate and lose weight over time. In his consecutive review, in which McCrory considered only studies in adults (≥18 years on average) and focusing primarily on experimental studies (short-term acute feeding trials or longer-term feeding trials) and longitudinal studies (prospective or retrospective, with the outcome of body weight change), the scientists from the Purdue University draws the following conclusions:
  • Acute feeding studies on breakfast skipping effects on energy intake and appetite later in the day show equivocal results.
  • Longer-term (2–3 weeks) randomized controlled trials do not show effects of breakfast skipping on weight change.
  • In prospective studies with 3.7–10 years follow-up, individuals who consume breakfast more frequently gain less weight.
McCrory also points out that the lack of standardization is a major obstacle that makes it difficult, if not impossible to compare the results from different labs / different experimental setups.
Let's assume you decide you want to have breakfast, because this works for you and you don't belong to the unfortunate people with an APO-E4-genetyp - in that case I'd suggest you consider having one or multiple eggs, incl. the yolk, to boost your cholesterol reverse transport and improve your cholesterol profile | learn more.
Bottom Line: Against that background we are currently, not at a point to prove a causal relationship between breakfast skipping and an increased obesity risk. Personally, I don't believe that there is a general connection - specifically not in those of us who eat clean and keep an eye on their overall food intake.

Furthermore, the average American breakfast consists of sugar-coated breakfast cereals with bacon... well, sort of. So skipping a meal like this is probably not going to hurt anyone. What's really intriguing, though, is the number of lunch skippers. A number I haven't been aware of, when I started writing this article, and a number I am planning to address in a future article - assuming I find more evidence than the two potentially relevant studies that popped up in my first cursory database search.
  • Brown, Andrew W., Michelle M. Bohan Brown, and David B. Allison. "Belief beyond the evidence: using the proposed effect of breakfast on obesity to show 2 practices that distort scientific evidence." The American journal of clinical nutrition 98.5 (2013): 1298-1308.
  • Kant, Ashima K., and Barry I. Graubard. "Secular trends in the association of socio-economic position with self-reported dietary attributes and biomarkers in the US population: National Health and Nutrition Examination Survey (NHANES) 1971–1975 to NHANES 1999–2002." Public health nutrition 10.02 (2007): 158-167.
  • McCrory, Megan A. "Meal skipping and variables related to energy balance in adults: A brief review, with emphasis on the breakfast meal." Physiology & Behavior (2014).