a prescribed selection of foods
"The doctor recommended that I follow his diet for two weeks to see if my cholesterol levels improve."
a legislative assembly in certain countries (e.g., Japan)
"After years of deliberation, the Japanese Diet finally passed the new environmental protection bill."
the usual food and drink consumed by an organism (person or animal)
"The wolf's diet consists mainly of deer and small mammals during the winter months."
The food and beverage a person or animal consumes.
"The researchers noted that their new anaerobic digestion process relies on diet to facilitate direct interspecies electron transfer between bacterial populations."
A council or assembly of leaders; a formal deliberative assembly.
Abbreviation of direct interspecies electron transfer.
In plain English: A diet is the specific foods and drinks you choose to eat regularly.
"On her new diet, she decided to stop eating sugar and start drinking more water."
Usage: As a noun in everyday usage, diet refers to the kinds of food a person or animal eats regularly. Avoid using it to mean direct interspecies electron transfer, which is a scientific term unrelated to nutrition.
follow a regimen or a diet, as for health reasons
"He has high blood pressure and must stick to a low-salt diet"
eat sparingly, for health reasons or to lose weight
"She decided to go on a strict diet after noticing that her clothes were getting tighter around her waist."
To regulate the food of (someone); to put on a diet.
"The doctor told him he needed to be monitored closely while they regulated his food intake after the surgery."
In plain English: To diet means to eat less food or choose healthier foods in order to lose weight.
"She decided to diet after realizing how much weight she had gained."
Usage: Do not use the verb "diet" to mean eating less; instead, say that someone is "on a diet." As a verb, it specifically means to restrict or regulate one's food intake for health reasons.
Containing less fat, salt, sugar, or calories than normal, or claimed to have such.
"After trying that new diet soda for a week, I finally realized it still contained enough hidden sugar to keep my energy levels steady."
In plain English: When used as an adjective, diet means something that is intended to help you lose weight or follow a specific eating plan.
"The diet plan he followed helped him lose weight."
Usage: Use "diet" as an adjective before a noun to describe food that is specifically prepared with reduced fat, salt, sugar, or calories compared to standard options. For example, say "a diet soda" rather than using the word to modify a verb or stand alone as a description of eating habits.
Alternative letter-case form of diet (council or assembly of leaders; a formal deliberative assembly).
"The rebel faction proposed that their demands be presented to the Diet in Kyoto for immediate consideration."
The word "diet" comes from the Ancient Greek díaita, which originally meant a way of living or regimen. It traveled into English through Old French and Middle English to describe both a plan for eating and an assembly of people.