The Energy Requirements and Metabolic Benefits of Wilderness Hunting in Alaska

The purported healthy aspects of subsistence foods have led to the popularity of the Paleo diet. There has been very little focus, surprisingly, on health benefits derived from the nomadic nature of humans during the Paleolithic era. The purpose of our study was to examine total energy expenditure (TEE), total energy intake (TEI), body composition, blood lipids, and intrahepatic lipid in humans during a 12-day Alaskan backcountry expeditionary hunting (ABEH) immersion. Four healthy men (age: 42 ± 3 year, BMI: 27 ± 1 kg/m ) were recruited for the study. TEE was measured using the doubly labeled water method and a food diary was utilized to assess TEI. Body composition was measured using dual energy X-ray absorptiometry (DXA); cross-sectional area of the thigh (XT) and intrahepatic lipid (IHL) were measured using molecular imaging. Blood samples were collected for the measurement of blood lipids. DXA, XT, IHL, and blood data were collected pre- and immediately post-ABEH. Results were analyzed using paired t-tests and considered significant at P < 0.05. TEE and TEI averaged 18.1 ± 1.2 and 9.1 ± 2.5 MJ/day, respectively, indicating substantial negative energy balance (-9.0 ± 1.3 MJ/day). There was a reduction in percent body fat (∆-3.3 ± 0.2%), total fat mass (∆-3.3 ± 0.4 kg), and visceral fat volume (Δ-261 ± 188 cm ). Lean tissue mass and XT was unchanged. There was a decrease in IHL (Δ-0.5 ± 0.1% water peak), and a trend (P = 0.055) toward reduction in LDL-cholesterol. We conclude that constancy of physical activity during negative energy balance may provide metabolic benefits above and beyond variations in diet that exist with the hunter-gatherer lifestyle.