Page 104 - Journal of Special Operations Medicine - Winter 2015

somewhat similar to whey, is also considered high qual- synthesis responses to feeding. Muscle protein synthe-
ity, although the muscle protein synthesis and long-term sis depends on the availability of sufficient energy and
muscle mass response to soy is somewhat lower than amino acids; thus, protein synthesis is generally reduced
that of whey. However, soy proteins are often less ex- during energy deficits to limit the degradation of muscle
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pensive than whey proteins and they are also dairy- and to support amino acid-derived blood glucose. Muscle
lactose-free, which may be preferred by some. protein synthesis responses to a protein-containing meal
are also blunted during an energy deficit because the
amino acids in food are largely diverted from muscle
Optimal Feeding During SOF Operations: A Need to support energy production. As such, protein require-
for Higher Protein and Higher Energy Diets
ments are higher during acute and prolonged periods of
Strenuous work during SOF training and missions may energy deficit.
impose large energy demands and, in many cases, se-
vere energy deficits, depleted body energy stores, muscle Several studies, including many from the military, have
mass loss, degraded performance, and increased injury assessed protein requirements during operations and
risk. 28–32 During Hell Week for Basics Underwater De- shown the muscle-sparing advantages of maintaining a
molition/SEAL training, energy expenditure averaged higher-protein diet during an energy deficit. 15,17,40–42 Physi-
about 5,364kcal/day over the first week (exclusive of the cally active young adults who consumed either 1.6 or 2.4g
cost of shivering), but sufficient energy and protein were protein per kilogram of BM during a 21-day, 40% energy
consumed, so no obvious energy deficits were noted. deficit (e.g., 1 kg of weight loss per week) lost more body
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When energy sources are limited, the physiologic and fat, spared more muscle mass, and maintained muscle
performance effects of such operations are largely un- protein synthesis responses to feeding to a greater extent
avoidable and occur to varying extremes depending on than those who consumed the current RDA for protein
the specific operation. 34–36 (0.8g protein per kilogram of BM [0.4g/lb BM]). Im-
15
portantly, no differences between those consuming 2.4g
For example, during a 7-day winter training operation, protein per kilogram of BM and 1.6g protein per kilo-
Norwegian Soldiers expended nearly 7,000kcal/day. gram of BM were noted, which suggests that during a
However, they only consumed half that energy, which re- moderate, sustained energy deficit, consuming protein
sulted in a severe energy deficit, increased inflammatory in amounts beyond two times the RDA confers no clear
state, muscle damage, soreness, fatigue, and diminished advantage. 15,41 These findings support current military
body weight, iron status, protein retention, and muscle recommendations for higher, but not excessive, protein
performance. A study of SOF candidates found they intakes during periods of increased metabolic demands.
37
expended approximately 5,200kcal/day during the simu-
lated urban combat phase of Small Unit Tactics within Many SOF operational scenarios likely result in meta-
the Special Forces Qualification Course. However, they bolic stressors and energy deficits that cannot be over-
only consumed about 2,500kcal/day, which resulted in a come by simply increasing dietary protein intake. For
greater than 50% energy deficit and loss of nearly 3kg example, protein intake was 1.7 g/kg BM in our study
of body weight over the 10-day observation period. In of Norwegian Soldiers, but measures of protein reten-
38
another study, SOF Soldiers expended about 3,900kcal/ tion suggested that muscle mass may have been lost.
day during pre-mission training and 4,500kcal/day dur- However, this was an effect we believe was primarily
ing the Combat Divers Qualification Course, which are reflective of the severe energy deficit produced during
36
well above the energy requirements stated in AR 40-25/ the training operation. Consuming more energy would
BUMEDINST 10110.6/AFI 44-141 of 3,250kcal/day. likely have offset the relative ineffectiveness of consum-
14
Other US SOF training courses, by design, produce un- ing a higher-protein diet during the training program.
avoidable energy deficits coupled with physiological and However, getting SOF to consume more food during op-
psychological declines to recreate the harsh realities of erations is a challenge. It is noteworthy that when Nor-
modern warfare. In a recent study, underfed (2,200kcal/ wegian Soldiers were provided more than 5,500kcal/
day) and sleep-deprived (0–5 hours per night) US Army day (e.g., four Norwegian Army arctic combat rations),
Ranger School students lost a significant amount of body they discarded up to 1,850kcal/day. The foods dis-
37
weight over the 61-day training course. Marked reduc- carded were primarily carbohydrate based (powdered
39
tions in circulating levels of anabolic hormones (e.g., beverages), a critical performance-sustaining macronu-
testosterone and insulin-like growth factor 1) occurred, trient that should not be overlooked during military op-
which may have exacerbated the loss of muscle mass. erations. Certainly, even if the Norwegian Soldiers had
consumed all the ration items provided, energy expen-
Consuming a higher-protein diet during such events ditures would still have exceeded energy intake, but the
may be an effective nutritional countermeasure during deficit would not have been as severe, and it is likely
unavoidable energy deficits by sparing muscle protein the higher protein intake of 1.7g/kg BM would have

92 Journal of Special Operations Medicine Volume 15, Edition 4/Winter 2015