The paleo community is accustomed to pushing back against dietary recommendations from the USDA and medical establishment. We like to argue that whole grains and legumes are universally detrimental to human health, that the high omega-6 fatty acid content of modern vegetable oils and grain-fed meat is responsible for the rise in cardiovascular disease seen in the last three decades, and that eating refined sugars causes decreased insulin and leptin sensitivity and is responsible for the current diabetes epidemic. These arguments are all extremely well backed-up with solid science, which is one of the reasons why the paleo diet is so successful. The paleo diet is the first diet to be based on comprehensive, current, high-quality scientific evidence of the effect of specific foods on our overall health (and structured with an ancestral health perspective). And while aspects of this diet will almost certainly change as more research is performed, the foundation is rock solid.
When it comes to whether or not breakfast is important, the paleo community is firmly divided. Many supporters of intermittent fasting prefer to skip breakfast at least a couple of times per week (Chris Kresser has stated that he skips breakfast 2-3 times per week), while other paleo gurus almost never eat breakfast at all (Mark Sisson has stated that he almost never eats breakfast, Mat Lalonde doesn’t eat until lunch and sometimes only eats one meal per day). The rationale behind skipping breakfast comes from two places: listening to our bodies and not eating until we’re hungry and the benefits of intermittent fasting. Many in the paleo community will tell you that breakfast is “just another meal” and there is nothing special about it. Many will tell you that if you aren’t hungry in the morning, you shouldn’t eat. I believe this to be true for people who are already extremely healthy, but if you have a history of metabolic derangement (i.e., if you were ever very overweight) or a history of adrenal fatigue, then skipping breakfast might not be such a good idea.
Cortisol management is a key goal of a paleolithic lifestyle and is essential for regulating inflammation, boosting the immune system, and regulating energy and mood. Cortisol is an essential hormone, involved not only in the body’s normal stress response, but also in regulating blood sugar and circadian rhythms. Cortisol is naturally at its highest in the morning. If you are getting adequate sleep and managing your stress, your cortisol level gradually decreases throughout the day and the first three quarters of your night’s sleep. There are two ways your cortisol can be disregulated. The first is chronically elevated cortisol, where your cortisol still decreases throughout the day but remains higher than normal at all times. The second is where your cortisol starts off low in the morning and increases through the day, which is the source of that second wind in the evening for many who are chronically sleep-deprived (this is called the “tired and wired”: pattern). If you have a history of adrenal fatigue, inadequate sleep or poor sleep quality, metabolic syndrome or obesity, or poor stress management, then you may not have normal cortisol levels (you might have chronically elevated cortisol or tired and wired cortisol expression). And even if you have made progress toward addressing these issues, your cortisol management may be tenuous. This is what happened to me.
The issue with skipping breakfast is that your body increases cortisol in order to stimulate glycolysis or gluconeogenesis to raise your blood sugar so that your body has energy for whatever you are doing. If you have a morning coffee, your cortisol will increase even more. In a very healthy individual with perfectly normal cortisol levels and well-regulated expression of hunger hormones, good insulin-sensitivity and good leptin-sensitivity, this rise is temporary and the body adapts beautifully. But if you don’t have normal cortisol levels or optimal insulin sensitivity or optimal leptin sensitivity or well-regulated ghrelin, this rise in cortisol in the morning can lead to increased cortisol throughout the day or abnormal swings in cortisol levels. Importantly, there is evidence that women are more susceptible to an exaggerated cortisol response to fasting. Women, therefore, are less likely to see a benefit to routinely skipping breakfast. When I started skipping breakfast on a regular basis, I noticed that my weight started creeping up and that my sleep quality deteriorated, classic signs of high cortisol (of course it took me two months to figure this out!). When I started eating breakfast again, I found that my hunger was less throughout the day, I lost the weight that I had gained quite quickly, and I started sleeping much better.
If your goal is weight loss, then skipping breakfast routinely is probably not the best choice (it’s probably fine and maybe even beneficial if you are already quite lean and very healthy). In fact, eating breakfast every day is one of the three habits known to correlate very strongly with not only weight loss success but also in maintaining that weight loss once your goal weight is reached. Of course, this doesn’t mean that you can’t experiment with Intermittent Fasting. And it doesn’t mean that skipping breakfast on a regular basis won’t work well for you in the future. Just be mindful of how it’s affecting you so that you can gauge whether or not breakfast really is the most important meal of the day for you.