Food-extrinsic factors are influences on how people perceive and evaluate a food item that come from outside the food itself. Food-extrinsic factors include food packaging, labelling, branding, price of the food item, cultural associations and meaning of the food item, background music, temperature, the overall context or the environment in which the food is consumed, and many others (Wang et al., 2019).

Food-intrinsic sensory factors are characteristics of a food item that human senses can perceive. These include the color of the food product, its texture, viscosity, etc. The taste and smell of the food item are the core food-intrinsic factors in most cases.

Free radicals are reactive molecules with unpaired electrons, causing them to seek stability by taking electrons from other molecules. This process, called oxidative stress, can damage cells and is linked to aging and diseases. Antioxidants neutralize free radicals by donating electrons, preventing harm.

Fullness hormones induce a feeling of satiety and reduce the desire to eat. Cholecystokinin (CCK) and leptin are examples of fullness hormones.

GABA is an inhibitory neurotransmitter that regulates brain activity by reducing neuronal excitability. It counterbalances the effects of excitatory neurotransmitters, contributing to the overall balance of neural signaling. GABA is known for its calming effects and is implicated in conditions like anxiety and epilepsy.

The gastrointestinal tract (GIT), also known as the gut, digestive tract, or alimentary canal, is a long, twisted hollow tube that extends from the mouth to the anus and is made up of interconnected hollow organs, including the mouth, esophagus, stomach, small intestine, large intestine, and anus (Greenwood-Van Meerveld et al., 2017).

The GBA-microbiota crosstalk is a bidirectional communication system between the gut, microbiota, and brain. This communication occurs physically or biochemically and interlinks the gut with the cognitive and emotional centers of the brain, thus ensuring adequate mental health and intestinal homeostasis (Mayer, Tillisch, & Gupta, 2015).

Genes are the instruction manuals of living organisms made up of intricate DNA sequences; their function is to direct the production of specific proteins and enzymes required for survival.

The germ-free (GF) animal model refers to the study of animals raised in a sterile environment free of microorganisms (i.e., beneficial and pathogenic microbes) for research purposes (Bhattarai & Kashyap, 2016).

Ghrelin is often referred to as the “hunger hormone.” It is produced by the stomach and stimulates appetite, signaling to the brain that it’s time to eat (Pradhan et al., 2013).