Why does my breakfast make me hungry?

"Why does my breakfast make me hungry?" After someone asked me this question for who-knows-how-many times, I decided to delve deeper into the possible reasons and mechanisms. I thought it would be a good idea to share my thoughts on the subject with you.

This is quite a long article, but I hope it is interesting enough to keep your attention and interesting enough to teach you a few things.

My heart was in my mouth a few months ago when it seemed like there was overwhelming evidence for the benefits of breakfast, but I was able to disprove it.

Why does breakfast make some people hungry?

As mentioned earlier, it was not without reason that this question piqued my interest beyond what could be attributed to food choices. In questionnaires, clients often stated that eating in the morning made them hungry before lunch and that this was sometimes the case less than an hour after breakfast.

On Facebook, in emails and in conversations, similar anecdotal experiences were mentioned too frequently to be explained by mere coincidence - or to be dismissed with a half-hearted response based on the assumption that everyone ate an unhealthy breakfast.

These people hadn't eaten fruit loops and a peanut butter sandwich with a glass of orange juice for breakfast - you know, the average person's breakfast that would make anyone hungry an hour later.

No, these people had eaten a typical fitness athlete's breakfast that included all kinds of foods that most of us have eaten for breakfast at one time or another - oatmeal, dairy, eggs, etc. It was often a meal characterized by moderate to high amounts of carbohydrates and protein, relatively low amounts of fat, and usually a useful amount of fiber.

You can spend all day debating how healthy or unhealthy whole grains and dairy are, but the fact remains that these foods can't provide a blanket explanation for the fact that breakfast triggers hunger in some people.

Heck, all you have to do is google "why does my breakfast make me hungry", "hungry after breakfast" or "breakfast makes me hungry" and you'll see that the forums are full of people reporting similar experiences.

I would count myself as one of those people. Skipping breakfast was by far the best change I made to my diet when I started Intermittent Fasting in 2006.

Like many other Intermittent Fasting practitioners, breakfast was something really annoying for me and skipping it made a huge difference. Compared to before, dieting almost went by itself.

Not to mention the long-term maintenance of weight. No more counting down the hours until lunchtime and no more feeling like I was on a diet - regardless of whether I was actually dieting, maintaining my weight or gaining weight.

For me and many others, skipping breakfast keeps hunger at bay much better than eating something in the morning - as paradoxical as this may sound. This is of course very interesting to me as it's a damn strange thing. Why are some people better off not eating anything at all in the morning? How can it be that under these specific circumstances you are better off with zero calories than with hundreds of calories. It just doesn't make sense...

So I set about trying to find an answer to this question and eventually came up with a satisfying hypothesis regarding the mechanism underlying this mysterious post-breakfast hunger surge that so many of us feel.

The original article ended up being 12000+ words long and had an over-the-top ridiculously academic feel to it, branching off into all sorts of only remotely related topics. The article was far too long for most people's attention span and far too technical for most people's level of understanding.

So yesterday I sat down and rewrote the whole thing, trying to get it across in the same way I would explain the topic to my girlfriend or an invisible friend I've told the whole thing to a few times now.

Note: As for the term breakfast, in the context of this article, I mean breakfast in the traditional sense, i.e. breakfast right after getting up - and not in the original sense of the word as the first meal after an overnight fast.

Let's define hunger after breakfast

Trying to define hunger after breakfast is something completely pointless. It's something you'll understand immediately because you've had the same experience, or something that will make you wonder what the hell I'm talking about because you simply don't have that problem. I suspect most of my readers will fall into the first category, which is why I won't spend much time on an academic discourse explaining the phenomenon beyond what I've already done. Simply put, some people get hungry - very hungry - and experience cravings of varying intensity shortly after eating breakfast in the morning.

In the realm of scientific literature, scientists who specialize in research on appetite, hunger, and addiction make a distinction between the previously mentioned terms (i.e. hunger, cravings, etc.), but since hunger after breakfast is described by clients and on forums as a subjective experience, without more detailed research on my part, I would guess that most people are referring to the same phenomenon when they talk about hunger after breakfast and use terms such as cravings, feeling hungry, ravenous hunger, etc. Personally, I would describe this feeling as hunger in the sense that most people would use the term hunger.

Hunger after breakfast sets in sometime between morning and noon - usually 30 minutes to 2 hours after breakfast and doesn't usually manifest itself in any symptoms beyond noticeable hunger. However, some people have mentioned that irritability and an impaired ability to concentrate on tasks that require greater amounts of focus occur at the same time as hunger after breakfast.

An important point is that the same meal does not produce this early and/or pronounced hunger when consumed later in the day. Hunger after breakfast cannot be explained by differences in food choices, but by certain individual factors and their interactions with a time-dependent effect of food intake on hormonal profile and metabolism.

An introduction to cortisol

Cortisol is the main culprit when it comes to post-breakfast hunger. Most of you will probably associate cortisol with stress and muscle catabolism and consequently with 'bad' and 'avoidance'. While this is partially correct, it is largely incorrect.

Since "partially correct" is responsible for many of the bullshit nutrition myths out there, it's useless. People who claim that eating six meals a day will boost your metabolism and that fasting results in starvation mode are "partially correct" - but most of what they say is just nonsense.

Context is often key and this is especially true when it comes to cortisol - which is why I'm going to give a brief introduction to this complex and multi-faceted hormone here. There are almost as many different definitions of stress as there are myths out there about cortisol but in terms of the former, the definition that appeals to me most from a minimalist perspective is the following:

"Stress can be defined as any challenge to an individual's homeostasis that necessitates an adaptive response by that individual."

Newport & Nemeroff, 2002.

Cortisol is released in response to a stressor to help you deal with that stressor efficiently - whether that stressor is a 20 repetition set of squats to complete exhaustion or an approaching deadline for an article that needs to be published. The role of cortisol during these challenges is to give you a boost, not to hinder you - whether the stressor is physical (e.g. training, injury, cold) or psychological (e.g. a complex cognitively demanding challenge).

Elevated cortisol levels during exercise allow us to go far beyond our non-stressed comfort zone and maintain an adequate rate of exertion without being unduly distracted by pain, hunger and fatigue for a longer period of time than would otherwise be the case. Cortisol improves muscle and glycogen metabolism, increases pain tolerance, reduces fatigue and boosts motivation.

Oh yes, does this answer the questions of those who have asked me about my thoughts on the use of cortisol blockers before training? No? Okay, then all I can say is good luck with those squats buddy....

Because of the cortisol response to a cognitive challenge, we can remember important facts faster and in more detail, maintain our concentration, stay alert and work on the computer all night if necessary. Cortisol improves our sensory perception, memory and alertness.

Most of this is covered in Robert Sapolsky's excellent book, Why Zebras Don't Get Ulcers, in which he also explains when and why cortisol becomes bad for us. In short, prolonged stress results in chronically elevated cortisol levels, which then do all kinds of bad things. There is a time and a place for cortisol. But in our hectic times, the thin line between work (stress) and leisure (rest) is often blurred.

With constant demands placed on oneself, never-ending obligations and endless opportunities to work (at the office, at home, etc.), the stressors of modern society are of great psychological variety and they are omnipresent if you allow them to be.

In stark contrast, the stressors of the past were more often short-term and physical in nature. Even though these were probably more serious and often life-threatening, there was a clear line between start and finish. And this explains the title of Sapolsky's book, which I cannot recommend enough and which should be read by anyone seeking a more detailed explanation of stress and the work of cortisol.

What Sapolsky does not explain in detail, however, is the cortisol response upon waking and the acute effects of cortisol on insulin secretion.

The cortisol response after waking up

Most people understand the concept of exercise and work as stressors - challenges to homeostasis - that require an adaptive response (cortisol). However, few people think of waking up after sleep and getting up in the morning as a particularly stressful event. However, waking up after sleep is indeed a major challenge to homeostasis.

The transition from a passive state of sleep to an active state of wakefulness is - in some ways - like going from a leisurely walk to a sprint where you have to give it your all. In the field of endocrinology, there is a special name for the events that follow waking up in the morning: The Cortisol Awakening Response (CAR - in German Kortisol Aufwachreaktion), on which there is a substantial amount of scientific research.

"Awakening stimulates ACTH release in the pituitary gland, which then stimulates cortisol release by the adrenal cortex. The rapid increase and peak in cortisol levels after waking is known as the Cortisol Awakening Response (CAR). Although CAR is believed to be part of the cortisol diurnal rhythm, CAR and cortisol diurnal rhythm represent two separate adrenocortical activities."

Shin et al, 2011.

As the body prepares to start the day, cortisol levels begin to rise steadily during the second half of the night, reaching a peak around the time you open your eyes. But as you struggle to get out of bed, cortisol levels continue to rise on the way to the shower. They will peak around 30 to 45 minutes later, which is around breakfast time.

We have now reached a key point in this hypothesis behind post-breakfast hunger, as the precise timing of the peak cortisol circadian rhythm (CAR) and the consumption of breakfast have some very interesting effects on insulin secretion.

The cortisol awakening response and insulin secretion

So you've showered, gotten dressed for the day and done all the things you do in the morning that are none of my business and now you sit down to eat your breakfast before work, school or whatever. I'm guessing it's now 30 to 45 minutes after you get out of bed, if you're like most people.

By the time you sit down to eat - or sometime around that period - your cortisol levels will be at their highest of the day, which should be around 20-30 nmol/l. In comparison, cortisol levels in the evening are around 2-5 nmol/l, which corresponds to the lowest value of the cortisol daily rhythm, if you're interested in the numbers. Of course, cortisol levels could rise further later in the day depending on the amount of stress you are exposed to, but this has nothing to do with our analysis.

"The early insulin response to a meal is higher in the morning than in the afternoon and this fact can only be partially explained by a moderate increase in incretin secretion. Rapid non-genomic effects of high cortisol levels in the morning may be at least partially responsible for this observation."

Vila et al, 2011.

The point is that the peak of the cortisol diurnal rhythm coincides with breakfast and that this is the only time during the day when cortisol levels reach sufficiently high levels to have an acute and marked effect on the food-induced insulin response.

If this sounds vague to the endocrinology enthusiast and those familiar with cortisol, let me briefly explain in plain language. What I mean here is that during the CAR maximum, cortisol levels rise high enough to "tantalize" the glucocorticoid receptors. This changes the non-genomic interaction between cortisol and insulin action from a suppression by the former, as can be observed at other times during the day due to mineral corticoid binding dominance, to a non-genomic stimulation or synergistic effect (Vila et al., 2010; Dallman et al., 1995)

If the last paragraph doesn't make much sense to you, then you now know why I had to rewrite and simplify the entire article.

Short-term* exposure to cortisol significantly increases insulin secretion and this is the key point here.

* As opposed to long-term exposure, which has the opposite effect.