GLOSSARY

Nutrient–Hormone Interaction is bidirectional interaction of nutrients and endocrine function.

Carbohydrate, protein and fat have different digestive and signaling routes that interact in mixed meals. Protein can stimulate both insulin and glucagon; insulin is not simply an added-sugar marker. Fat and fiber can shift timing through gastric-emptying effects. Program quality depends on energy, nutrients, tolerance and fit with training rather than producing the lowest possible hormonal response after every meal or treating physiological insulin secretion as inherently undesirable.

Insulin is secreted by pancreatic beta cells and coordinates nutrient use and storage rather than simply being a fat-making hormone. Important effects include muscle and adipose glucose uptake, suppression of hepatic glucose production and regulation of lipolysis. Not every cell needs insulin for glucose entry. Postmeal concentrations vary with meal composition, tissue sensitivity and clearance, so one insulin excursion cannot determine overall dietary quality or an athlete's nutritional needs.

For practical use, record meal and training timing, sleep and hunger alongside actual intake and performance trends. When a marker changes, first examine measurement conditions and plausible explanations; food decisions should support adequate supply, tolerance and recovery rather than ending the assessment at one molecular signal or assuming a concentration change automatically establishes a useful intervention.

Glucagon is mainly secreted by alpha cells and supports glucose availability, prominently through the liver. Its response is not simply the inverse of insulin: amino acids and meal type matter, and both can rise after protein. Direct skeletal-muscle effects should not be assumed equivalent to hepatic effects. Their ratio is context-dependent rather than a food-quality score, and changes need secretion, clearance and tissue actions considered together.