Thursday, March 31, 2016

New Paleo Study by Freese et al

A paper was recently published in the Journal of Evolution and Health (the journal of the Ancestral Health Society) that looked at the effects of simulating a few aspects of a hunter-gatherer lifestyle for 4 days and 3 nights

This study included 13 participants (7 male, 6 female), all Caucasian.  Average age was 39 (± 8.1).  9 of participants had a BMI between 19.3-25, 4 had a BMI between 25-27.4.  7 exercised for more than 3 hours per week and 1 was a smoker

  • Outdoors: the participants “lived and slept outdoors with no shelter”
  • Diet: the participants received fruits, nuts and tubers to eat for lunch and a Paleo dinner.  “The dietary composition of foods was aimed to reconstruct a paleolithic diet based on the recommendations of Cordain and others”.  The participants consumed 1567 calories per day on average during the study (the participants’ usual calorie intake isn’t reported) with a macronutrient ratio of 24:54:22 (P:F:C) (see table 2 for detailed information on the foods they ate).  (The participants got their water from a “nearby holiday apartment”)
  • Exercise: the participants hiked for 3.42 hours per day and did 2.5 hours of other forms of physical activity (“Other activities associated with nomadic hunting and gathering were: swimming, climbing, lifting and building a fire”)
  • Fasting: the participants had an intermittent fasting period of at least 12 hours per day, as they didn’t eat until noon and did the 4+ hour hike while fasted
  • Sleep: the participants slept an average of 7.9 hours.  That being said the participants probably had also benefited from less night-time light (depending on the moon).  (As this study was done in Germany it could be important to know what season is was and what the weather was like) 

The rationale of the study is that various aspects of our evolutionary mismatch leads to low grade inflammation, which promotes obesity and insulin resistance, and that exercise while fasted may be particularly protective against this.  I have written previously on how inflammation is an attractive mechanism of insulin resistance, but current evidence from RCTs in humans doesn’t support that hypothesis so far (blog).  I like the idea of researching tools to mitigate postprandial inflammation, but I doubt much would change in a fasted blood sample after 4 days

The researchers made many measurements related to the immune system/inflammation, the metabolic syndrome and body composition (see table 4 and 5 for more info).  Significant changes included:


Pre
Post
Change
Weight (kg)
69.7
67.0
-3.9%
RDW (%) (RBC distribution width)
12.9
12.5
-2.9%
Thrombocytes (nL)
212.5
235.5
10.9%
Lymphocytes (%)
31.1
26.7
-14.0%
Fasting Glucose (mg/dL)
87.2
71.3
-18.2%
CRP high sensitive (mg/L)
0.4
1.1
169.6%
Insulin (uU/mL)
4.2
2.1
-50.1%

With 1597 calories and all that exercise it’s not surprising that the participants, who appear already quite healthy, lost some weight and reduced their fasting glucose and insulin levels.  Surprisingly high sensitivity CRP increased quite a lot (despite the reduction in glucose and insulin levels) and the authors comment on this saying “We suppose, that living in the wild stimulates the innate immune system as shown by Qing [52] and Park [53] via activation of proinflammatory pathways in order to anticipate evolutionary old danger signals such as bacteria, viruses, insects or predators.”  That makes sense and the high level of exercise may have also contributed

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