Underconsumption and Performance
PART IV EXPLORES THE IMPLICATIONS of underconsumption for physical and cognitive performance. As presented in Chapters 14 and 15, research suggests that decrements in physical and cognitive performance do not begin until 10 percent or more of body weight is lost in well-hydrated individuals. Chapter 14 shows that the nature and duration of the physical performance, the performance tasks themselves, body composition at the time of testing, and rate of weight loss must be considered when assessing physical performance. The author reviews a number of physical performance tasks and situations that indicate decrements in physical performance are not evident with small degrees of weight loss or losses of body fat; rather, most evidence suggests that physical performance is maintained until weight loss approaches or exceeds 10 percent of initial weight.
The review of underconsumption and cognitive performance in Chapter 15 emphasizes methodological issues, such as establishing cognitive test standardization and reliability. Changes in cognitive performance can be attributed to underconsumption of rations, effects of the field setting, and adverse physical and emotional factors. Using fewer studies than those available to assess physical performance, the author finds that cognitive performance may be degraded when lowered energy intake leads to weight loss in excess of 10 percent of initial body weight.
In the final chapter of this section, the author uses data collected on athletes to show that caloric underconsumption has negative effects on lean body mass and physical performance. Energy deficits can be minimized with