FASTING DIET FEEDS FROM OUR DEEP EVOLUTIONARY PAST

by Jordan Pennells – Originally posted on LIFEApps

Am I the only one who is drawn to the fridge late at night in search of a little snack?

It is impressive how much sway hunger can have on our lives, at times adversely affecting our mood, attention and energy levels. But how often do most of us in developed countries really experience hunger? Intense, gnawing hunger, twisting your stomach in knots and hijacking the brain?

During this month of Fasting February, I have been looking deeper into hunger, both by researching its evolutionary drivers and by experiencing mild hunger first-hand. After starting a 16-hour fasting schedule (otherwise known as a daily 16:8) this month with no prior experience, I’m here to share some of the challenges and benefits I have faced along the way. I’m also here to share why this diet makes sense in the context of dietary evolution, from our hunter-gatherer ancestors through to the modern Western world.

When starting time-restricted eating, typically in the form of condensing all of your food intake into an 8-hour window, it’s all but inevitable that you’ll have to choose which meal to skip. My advice to you would be to not start by skipping lunch, especially when you happen to be doing hours of physically draining fieldwork out in the blazing South-East Queensland sun on your first day of fasting!

Sorghum-farm-Banner

Sorghum farm in Queensland, Australia. Source: QAAFI

The option I decided upon by Day 2 of my Fasting February is the option of skipping breakfast. Or should I say, the early AM meal, because in the literal sense “breakfast” is simply the first meal you have after an overnight fast, irrelevant of whether this occurs in the morning or afternoon.

In fact, I think the notion of a typical breakfast is set to change in the coming decades, both in terms of what and when. We’ve all heard the axiom that “breakfast is the most important meal of the day”. However, this sentiment has been shaped more than we’d care to realize by marketing techniques in the 1940s advocating for food items such as cereal and bacon. Cereal was promoted as a treatment of chronic ailments such as indigestion, but is looked upon in a less favorable light now by modern dietitians due to its typically high sugar content and reduced levels of resistant starch from processing1.

Even ~70 years on, the role of breakfast in our health is hotly debated in the nutrition and dietetics fields. Breakfast has been shown to improve cognitive performance of children and adolescents in the morning, especially if they have been previously malnourished2. But one thing is for certain: The worst thing you can do is to have an unhealthy, high sugar breakfast, as is found in many Western breakfast options. This includes adding sugar to your morning coffee!

Intermittent Fasting (IF) is an increasingly popular alternative to the typical morning breakfast. The science-backed benefits of making this lifestyle change have been described in detail in a previous post, but some of my personal experiences include:

1. Having more time in the morning.
2. Not feeling bloated and lethargic after a big breakfast.
3. Feeling a deeper appreciation for the availability & taste of food after breaking a fast.
4. Considering more deeply my choice of food.
5. Stronger effect of your morning coffee on an empty stomach!

I didn’t achieve these benefits without overcoming certain challenges associated with counteracting ingrained food habits. Personally, late-night snacking is one of these habits for me. Counterintuitively, I found this earlier time during my fasts (the late-night snack hour, or within the first few hours of starting my fast in the evening) to come with the strongest cravings. When it came time to eat dinner, I initially found myself eating faster, as well as eating more food to account for the upcoming fasting period.

You should refrain from eating in this way in order to “make up” for fasting. Eating at a slower pace will also help you become a more mindful eater (2). Additionally, you may find that your appetite shrinks when incorporating IF into your lifestyle.

We normally eat pretty much as soon as hunger arises, without experiencing the evolving sensation over time. [Editor’s note: The physical sensation of hunger comes from the hormone ghrelin among others, which enhances appetite and food intake and makes you look for high-calorie food options.] It makes you think about whether most of us ever experience actual hunger, the kind that has been researched to cause immense physical discomfort, fixation on food and deterioration of self-assessed cognitive function3. While the effects of extreme hunger and malnutrition are debilitating, experiencing mild hunger can be an important step in mindful monitoring of your body, having a sharper awareness of what your body needs, and correcting a dysfunctional diet. [Editor’s note: Mild hunger also signals the body to increase expression of stress resistance genes, through a variety of processes.] The claim that skipping a meal irrevocably impacts adult brain function is tenuous, especially in the context of our evolutionary history.

Tools to manage intermittent supply of food are built into our biology, with “organs for the uptake and storage of rapidly mobilizable glucose” (in other words, the liver and liver glycogen stores) being conserved across mammals4. It was likely common for ancestral human hunter-gatherers to go for days without acquiring a substantial meal.

“The ability to function at a high level, both physically and mentally, during extended periods without food may have been of fundamental importance in our evolutionary history.” – Mattson et al., 2014

In this situation, there would have been a strong selection pressure to maintain brain and body function during physically and mentally grueling hunting raids, else any individual unable to persevere would have died off. Back to the basics of survival of the fittest! In some sense, we have been evolutionarily crafted to survive for periods without food.

Juxtaposed in the modern Western world is the trend for continuous, gluttonous eating, which jumps out at me as an injustice to our evolutionarily-acquired feats of fasting.

 

“The rising tide of obesity is strongly associated with daily calorie intake and sedentary lifestyle-promoting transportation.” Mattson MP, Allison DB, Fontana L, et al. Meal frequency and timing in health and disease. Proc Natl Acad Sci U S A. 2014;111(47):16647-53.

This is like topping up your car every day with low qualify fuel and letting the impurities build up over time, whereas fasting is like flushing out your engine. Not only this, but fasting makes you more mindful of the quality of fuel that you’re feeding into your body, helping you make better food choices.

This newfound awareness of food, and our profound evolutionary relationship with it, has made me more confident that I can concentrate when experiencing hunger, appreciate each meal that I do have, and make better choices late at night when then fridge is beckoning.

So while IF might seem like another fad from the dieting world, it is actually a lifestyle factor built deep into our evolutionary past. Natural selection has ensured that our brain and body can still function under calorie restricted conditions. For example, our body produces ketones as brain fuel when glucose isn’t readily available. If health is one of your priorities and you’d rather emulate the dietary structure of our hunter-gatherer ancestors than fall in the trap of the modern diet, then feed IF into your lifestyle this month during Fasting February and beyond!

References:

  1. Alsaffar, A.A., 2011. Effect of food processing on the resistant starch content of cereals and cereal products – a review. Int. J. Food Sci. Technol. 46, 455–462. https://doi.org/10.1111/j.1365-2621.2010.02529.x
  2. Hoyland, A., Dye, L., Lawton, C.L., 2009. A systematic review of the effect of breakfast on the cognitive performance of children and adolescents. Nutr. Res. Rev. 22, 220–243. https://doi.org/10.1017/S0954422409990175
  3. Keys et al. The Biology of Human Starvation (2 volumes), University of Minnesota Press, 1950
  4. Mattson et al. Meal frequency and timing in health and disease. Proc. Natl. Acad. Sci. 111, 16647–16653. https://doi.org/10.1073/pnas.1413965111

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