GLOSSARY

Protein Energy Store is energy embodied in body proteins. These proteins have functional roles and are not a dedicated energy reserve equivalent to adipose triglyceride.

The body stores substantial energy in adipose triglyceride, more limited carbohydrate as glycogen, and energy in functional proteins that can also be broken down. Protein tissue is not a dedicated expendable fuel tank. Glycogen is stored with water, so its depletion and restoration can shift body mass rapidly. Mobilizing a fuel does not prove that it is oxidized or that total fat stores are falling. Net storage over time depends on both entry into and removal from the relevant pool.

Energy and nutrients are distributed among oxidation, synthesis and storage through interacting pathways. The composition of weight gained or lost depends on more than the numerical calorie gap. Protein, training and initial body composition are relevant, and wet tissue contains variable water. The energy content of a tissue is not identical to the dietary energy required to build it. A single constant energy-per-kilogram rule therefore cannot precisely predict all future body-mass changes or distinguish muscle from other lean components.

Over a defined interval, a difference between metabolizable energy intake and energy expenditure changes stored body energy. This principle does not imply that daily scale weight directly reveals energy balance. Water, glycogen and gut contents also contribute to body mass. Intake and expenditure influence each other through behavior and physiology, so projecting the same daily deficit indefinitely creates unrealistic predictions. Interpret the energy equation together with its timescale and the composition of the tissues changing.

Fat-free mass includes water, protein, minerals and other nonfat constituents. It therefore includes organs and bone as well as skeletal muscle. Lean body mass, fat-free mass and lean soft tissue can have different technical meanings, although terms are sometimes used loosely. A short-term rise in a device's lean-mass estimate can reflect hydration or glycogen rather than new contractile protein. Check the device definition and testing conditions before calling a change muscle growth.

Energy expenditure can change during weight loss because a smaller body costs less to maintain and move, and because additional adaptive responses may occur. These explanations should be distinguished rather than calling every reduction a damaged metabolism. Appetite and spontaneous movement can also change. The size and persistence of adaptation vary. Reassess trends and recovery under comparable conditions instead of assuming that an equation's initial prediction remains the correct maintenance intake throughout a changing training and weight-loss period.

Body mass and composition can affect the demands of moving the body, but their relationship to performance depends on the task. Absolute strength, power, technique, endurance, skill and recovery may matter differently between sports. Dividing performance by mass can improve a ratio even when absolute performance declines. A nutrition change should therefore be judged against the actual event and health outcomes. There is no universal body-fat percentage or competition weight that guarantees success across athletes.