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Here’s What Happens When You Live Like A Hunter Gatherer (Paleo/IF Style) For 4 Days!

For 4 days and 3 nights, 13 strangers must survive in the wilderness without shelter or modern technology, foraging for whole foods and living by the light of the sun, eating only at night. Will these tireless daytime hours yield starvation? Will their health go to exhausted shambles?

Nope, this isn't the pitch for a new reality TV show, but rather the set-up of the most page-turning medical study I've read to date: "To Restore Health, “Do we Have to Go Back to the Future?” The Impact of a 4-Day Paleolithic Lifestyle Change on Human Metabolism." This fascinating 2016 German experiment explores the hypothesis that changes in our lifestyle (such as eating hours, physical activity, diet composition, and modern stressors) have instigated a state of low-grade inflammation which encourages obesity, diabetes, and disease.


This may come as a surprise, but eating is inherently inflammatory. Ya see, when we eat, we welcome foreign substances into our body, open house style. This means potential bacteria, viruses, and the like just might set up shop inside us. Of course, our bodies are equipped to handle this, and in the healthy metabolic state, mealtime releases a cascade of anti-inflammatory substances which regulate the immune system appropriately, including immunoglobulin A (IgA), lactoferrin, and lysozyme. Our modern inflamed and often overweight bodies, however, often lack adequate amounts of these protective substances, while modern diets full of refined fats, sugars, grains, and grain-fed animals further encourage inflammation. Weight gain from too much food and too little activity further primes this inflamed state, which may be the root cause of many, if not most, degenerative disease.

What has been shown to lower inflammation? Calorie restriction, fasting, and moving before eating! Which we don't do so much today. More on that in a bit!


As discussed in the study, the movement and eating patterns of historical hunter gatherers were basically the opposite of what we do today: "exercise" was mandatory to secure food, while eating was a luxury. You really only got to eat, if you put in a valiant physical effort to secure your food - a task which occurred in a fasted state. This meant the natural lifestyle pattern for hunter gatherers involved daytime fasted activity hunting for food (foraging), followed by eating at night as reward for hunting and gathering... if you triumphed in the hunt! The likelihood of food success was determined by a myriad of factors, including the seasons and environment, as well as one's personal fitness level, intuition, and dexterity. Only the strong and smart survive!

In fact, our inherent cortisol rhythm (before we screw it up) supports this evolutionary daytime fasted state. A natural morning spike in cortisol stimulates the release of stored fats and sugars into the blood stream, giving us energy to run around and find food for that nightly feast - which historically featured moderate or even minimal calories from nutritious whole food sources. Come nighttime, cortisol levels should dwindle, as we eat and relax into a restorative, nutrient-processing state. We're meant to run around in tune with the sun, fueled by a plethora of energy from our body fat, not constant snacks, until we ultimately eat at night and sleep in the darkness. What happens now? Though, we still may awake with a spike of cortisol (or force it with coffee if absent), we quickly suppress it with breakfast. We then often live a sedentary day in discordance with the sun, and fill our evenings with light (and not in a feel-good Zen way.)

The study also emphasizes our dysregulated insulin and blood sugar. Historically, raising blood sugar was key for survival. Without it, we wouldn't be able to access stored energy necessary for daily fasted activity. This may be a reason we have tons of hormones which can raise blood sugar (cortisol, thyroid, adrenaline, growth hormone, etc.), but only one which lowers it (insulin). In other words, we're primed to access our stored energy at any time... which becomes problematic when we never access our stored energy at any time, but rather constantly eat food instead. Eating releases insulin, which historically was only substantially raised after the nightly feast to assimilate nutrients and lower blood sugar. Now we constantly raise blood sugar with food and hormones, and also constantly try to lower it with insulin. This leads to a terrible blood sugar rollercoaster, as well as insulin resistance as cells stop responding to the constant insulin hits. All of this, of course, further increases inflammation, perpetuating the problem.

Basically, we've become metabolic over-inflated ghosts of our prior selves. Is all lost? Can we recover our true metabolisms by reverting back to the way things were? That's what this study aimed to find out...


To test the influence of a simulated stone-age lifestyle on markers of inflammation, 6 women and 7 men, aged 22-49 were dropped into Delux National Park bordering Luxembourg and Germany, for 4 days and 3 nights. They were a collection of scientists, students, physicians and health professionals who were generally healthy (though 4 were overweight) and didn't use prescription drugs. Half exercised more than 3 hours per week. The group was stripped of all technology, but accompanied by a guide with a cell phone for emergencies. (That said, the guide had no knowledge of the specific area).

Here's how their days went down:

  • They assumed a pattern of mostly daytime fasted activity (hiking, foraging, swimming, etc.) followed by nighttime eating.
  • Each morning, the participants filled water jugs, and were provided berries, fruits, nuts, and tubers for the day. That said, they had to engage in physical activity for at least 4 hours before consuming these, with no eating before noon. Coupled with their nighttime sleeping fast, this ensured at least 12 hours of fasting.
  • The group ended up averaging 3.42 hours hiking and 2.5 hours of other activity, like swimming, climbing, lifting, and building fires.
  • Because hunting required a license, the participants were provided with Paleo meals at sunset, composed of around 22% carbs, 24% protein, 54% fat, and yielding an average of 1567 calories. These meals featured meat (chicken, beef, and fish), veggies (like zucchini, salad greens, and cauliflower), nuts (walnuts and almonds), fruits (like berries, peach, pear, and grapes), starches (like carrots and turnips) well as butter and olive oil.
  • The participants lived outdoors, with no shelter.
  • They had no technology, and lived by the light of the sun.
  • They slept around 8 hours each night.
  • The modern chronic stressors of life (traffic, deadlines, etc.) were replaced with physical stressors (physical activity, danger signals, thirst, hunger, etc.)


Waiting with baited breath to know what happened? The researchers measured 38 health factors in the participants via blood tests and other body sensors. After the experiment, they found:

  • body weight decreased (-3.9%)
  • body fat decreased (-7.5%)
  • BMI decreased (-3.8%)
  • visceral fat decreased (-14.4%)
  • fasting glucose decreased (-18.2%)
  • fasting insulin decreased (-50.1%)
  • triglycerides decreased (-17.7%)
  • C-reactive protein increased (169.9%)

These results were shocking. In a mere 4 days, the participants rapidly reached significantly healthier body fat and blood sugar biomarkers for metainflammation. Interestingly, C-reactive protein, also a biomarker of inflammation, did increase. The researchers attributed this to an activation of the innate immune system stimulated by outdoor living, in response to potential pathogens in the wild.


Yep, I'm sort of obsessed with this study. For starters, it takes a look at Paleo and intermittent fasting (IF). Oh hey! But perhaps most importantly, it goes beyond simple diet experiments to look at what happens when you stimulate a synergistic conglomerate of "Paleo" conditions, including living situations, physical activity, circadian rhythms, physical rather than chronic stressors, as well as food intake, composition, and timing. So many things! Of course, the study was quite short term, the participants weren't even physically hunting their food, were provided with water, and even had access to easy refined fats like butter and olive oil. In other words, they were still a bit "privileged" compared to hunter gatherers. But in any case, the results are fascinating, showing the Paleo lifestyle can initiate so much metabolic improvement, in so little time.

As a personal side note, this study makes me feel better about one of my (many) weird habits. In a world where #ToGo is God and people pay to have food shipped to their door, I actually go to the grocery store almost every day. I'm seriously not kidding. Since adopting a Paleo/IF lifestyle, I've just found something doesn't feel right if I don't exert a reasonable amount of energy to acquire my food. The only time I feel "ok" in pulling out ready-made meals, is when I spend the entire day running around with some degree of madness.

I guess there's something to that.

In any case, while I personally have no desire to forsake my modern life for a literal caveman lifestyle (much more of hotel girl than a camper myself), I definitely think living caveman style  in the modern world may be key for health and longevity. Despite the raised eyebrows, I plan to keep on fasting, feasting, moving, sleeping, and living. Who's with me???


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