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New Findings What is the topic of this review? There is a need to revisit the basic principles of exercise mass and water balance, the use of common equations and the practice of interpreting outcomes. What advances does it highlight? We propose use of the following equation as a way of simplifying exercise mass and water balance calculations in conditions where food is not consumed and waste is not excreted: ∆body mass − 0.20 g/kcal−1 = ∆body water. The relative efficacy of exercise drinking behaviours can be judged using the following equation: percentage dehydration = [(∆body mass − 0.20 g kcal−1)/starting body mass] × 100. Changes in body mass occur because of flux in liquids, solids and gases. This knowledge is crucial for understanding metabolism, health and human water needs. In exercise science, corrections to observed changes in body mass to estimate water balance are inconsistently applied and often misinterpreted, particularly after prolonged exercise. Although acute body mass losses in response to exercise can represent a close surrogate for body water losses, the discordance between mass and water balance equivalence becomes increasingly inaccurate as more and more energy is expended. The purpose of this paper is briefly to clarify the roles that respiratory water loss, gas exchange and metabolic water production play in the correction of body mass changes for fluid balance determinations during prolonged exercise. Computations do not include waters of association with glycogen because any movement of water among body water compartments contributes nothing to water or mass flux from the body. Estimates of sweat loss from changes in body mass should adjust for non-sweat losses when possible. We propose use of the following equation as a way of simplifying the study of exercise mass and water balance: ∆body mass − 0.20 g kcal−1 = ∆body water. This equation directly controls for the influence of energy expenditure on body mass balance and the approximate offsetting equivalence of respiratory water loss and metabolic water production on body water balance. The relative efficacy of exercise drinking behaviours can be judged using the following equation: percentage dehydration = [(∆body mass − 0.20 g kcal−1)/starting body mass] × 100.

Development of n‐3 fortified, shelf‐stable foods is facilitated by encapsulated docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), since natural n‐3 food sources cannot withstand high temperature and prolonged shelf life. Organoleptic stability of n‐3 fortified, shelf‐stable foods has been demonstrated, but chemical changes in the food matrix throughout storage could conceivably impact digestibility of the protein‐based encapsulant thereby compromising n‐3 bioavailability. We assessed the effect of prolonged high‐temperature storage and variations in food matrix (proteinaceous or carbohydrate) on the time course and magnitude of blood fatty acids changes associated with ingestion of n‐3 fortified foods. Low‐protein (i.e., cake) and high‐protein (i.e., meat sticks) items were supplemented with 600 mg encapsulated DHA+EPA, and frozen either immediately after production (FRESH) or after 6 months storage at 100°F (STORED). Fourteen volunteers consumed one item per week (randomized) for 4 weeks. Blood samples obtained at baseline, 2, 4, and 6 h post‐consumption were analyzed for circulating long‐chain omega 3 fatty acids (LCn3). There was no difference in LCn3 area under the curve between items. LCn3 in response to cakes peaked at 2‐h (FRESH: 54.0 ± 16.8 μg/mL, +18%; STORED: 53.0 ± 13.2 μg/mL, +20%), while meats peaked at 4‐h (FRESH: 51.9 ± 12.5 μg/mL, +22%; STORED: 53.2 ± 16.9 μg/mL, +18%). There were no appreciable differences in time course or magnitude of n‐3 appearance in response to storage conditions for either food types. Thus, bioavailability of encapsulated DHA/EPA, within low‐ and high‐protein food items, was not affected by high‐temperature shelf‐storage. A shelf‐stable, low‐ or high‐protein food item with encapsulated DHA/EPA is suitable for use in shelf‐stable foods.

Objective The US Army recruits new soldiers from an increasingly obese civilian population. The change in weight status at entry into the Army between 1989 and 2012 and the demographic characteristics associated with overweight/obesity at entry were examined. Methods 1,741,070 unique individuals with complete sex, age, and anthropometric information contributed data to linear and logistic regressions examining time trends and associations between demographic characteristics and overweight/obesity. Results The prevalence of overweight (body mass index 25

Objective: Energy density (ED) and eating rate (ER) influence energy intake; their combined effects on intake and on postprandial pancreatic and gut hormone responses are undetermined. To determine the combined effects of ED and ER manipulation on voluntary food intake, subjective appetite, and postprandial pancreatic and gut hormone responses. Design and Methods: Twenty nonobese volunteers each consumed high (1.6 kcal g−1; HED) and low (1.2 kcal g−1; LED) ED breakfasts slowly (20 g min−1; SR) and quickly (80 g min−1; FR) ad libitum to satiation. Appetite, and pancreatic and gut hormone concentrations were measured periodically over 3 h. Ad libitum energy intake during the subsequent lunch was then measured. Results: Main effects of ED and ER on energy intake and a main effect of ER, but not ED, on mass of food consumed were observed, FR and HED being associated with increased intake (P < 0.05). Across all conditions, energy intake was highest during FR-HED (P ≤ 0.01). Area under the curve (AUC) of appetite ratings was not different between meals. Main effects of ED and ER on insulin, peptide-YY, and glucagon-like peptide-1 AUC (P < 0.05) were observed, FR and HED being associated with larger AUC. No effects on active or total ghrelin AUC were documented. Total energy intake over both meals was highest during the FR-HED trial with the greatest difference between FR-HED and SR-LED trials (P ≤ 0.01). Conclusion: Consuming an energy dense meal quickly compounds independent effects of ER and ED on energy intake. Energy compensation at the following meal may not occur despite altered gut hormone responses.

Humans demonstrate a remarkable ability to regulate daily body water and electrolyte balance so long as food and fluid are readily available. The imposition of exercise and environmental stress can, however, challenge this ability. Most circumstances involving physical exercise require the formation and vaporization of sweat as the principle means of heat removal in man. Sweat losses, if not replaced, reduce body water volume and electrolyte content. Excessive body water or electrolyte losses can disrupt physiological homeostasis and threaten both health and performance. Persons often dehydrate during physical activity or exposure to hot weather because of fluid non-availability or a mismatch between thirst and body water losses. In these instances, the person begins the task with normal total body water and dehydrates over a prolonged period. This scenario is common for most athletic and occupational settings, however, in some situations the person might begin exercise with a body water deficit. For example, in several sports (e.g., boxing, power lifting, wrestling) athletes frequently dehydrate to compete in lower weight classes. Also, persons medicated with diuretics may be dehydrated prior to initiating exercise. If sodium chloride deficits occur then the extracellular fluid volume will contract and cause "salt depletion dehydration." A sodium chloride deficit usually occurs due to sweat sodium losses combined with excessive water consumption, but a sodium deficit can also occur without excessive water intake owing to high sweat sodium losses. Both of these scenarios produce sodium dilution more commonly known as hyponatremia or "water intoxication". This chapter reviews the physiology, needs, and assessment of human water and electrolyte balance. The extent to which water and electrolyte imbalances affect temperature regulation and exercise performance are also considered.

Physically intense military training may diminish whole-body protein retention and increase dietary protein requirements. This study characterized the effects of military training on whole-body protein turnover in 21 Soldiers participating in a 7-day winter training exercise that culminated in a 3-day, 54 km ski march. Energy expenditure was assessed during training using doubly labeled water (D218O), and protein turnover, synthesis, breakdown, and net balance were measured at baseline (BL), day 4 (PRE, prior to the ski march), and day 7 (POST, following the ski march) using 15N-glycine. Energy (kcal·d-1) intake increased (P 0.0...