The process of making a diet version of a food usually requires finding an acceptable low-food-energy substitute for some high-food-energy ingredient.[16] This can be as simple as replacing some or all of the food's sugar with a sugar substitute as is common with diet soft drinks such as Coca-Cola (for example Diet Coke). In some snacks, the food may be baked instead of fried thus reducing the food energy. In other cases, low-fat ingredients may be used as replacements.
The purpose of the Mayo Clinic Diet is to help you lose excess weight and to find a way of eating that you can sustain for a lifetime. It focuses on changing your daily routine by adding and breaking habits that can make a difference in your weight, such as eating more fruits and vegetables, not eating while you watch TV, and moving your body for 30 minutes a day.

Several organisations have begun calling for a new kind of agriculture in which agroecosystems provide food but also support vital ecosystem services so that soil fertility and biodiversity are maintained rather than compromised. According to the International Water Management Institute and UNEP, well-managed agroecosystems not only provide food, fiber and animal products, they also provide services such as flood mitigation, groundwater recharge, erosion control and habitats for plants, birds, fish and other animals.[70]

Packaged foods are manufactured outside the home for purchase. This can be as simple as a butcher preparing meat, or as complex as a modern international food industry. Early food processing techniques were limited by available food preservation, packaging, and transportation. This mainly involved salting, curing, curdling, drying, pickling, fermenting, and smoking.[106] Food manufacturing arose during the industrial revolution in the 19th century.[107] This development took advantage of new mass markets and emerging technology, such as milling, preservation, packaging and labeling, and transportation. It brought the advantages of pre-prepared time-saving food to the bulk of ordinary people who did not employ domestic servants.[108]
For some foods alternative ingredients can be used. Common oils and fats become rancid relatively quickly if not refrigerated; replacing them with hydrogenated oils delays the onset of rancidity, increasing shelf life. This is a common approach in industrial food production, but recent concerns about health hazards associated with trans fats have led to their strict control in several jurisdictions.[57] Even where trans fats are not prohibited, in many places there are new labeling laws (or rules), which require information to be printed on packages, or to be published elsewhere, about the amount of trans fat contained in certain products.
France has various appellation systems based on the concept of terroir, with classifications ranging from Vin de Table ("table wine") at the bottom, through Vin de Pays and Appellation d'Origine Vin Délimité de Qualité Supérieure (AOVDQS), up to Appellation d'Origine Contrôlée (AOC) or similar, depending on the region.[75][76] Portugal has developed a system resembling that of France and, in fact, pioneered this concept in 1756 with a royal charter creating the Demarcated Douro Region and regulating the production and trade of wine.[77] Germany created a similar scheme in 2002, although it has not yet achieved the authority of the other countries' classification systems.[78][79] Spain, Greece and Italy have classifications based on a dual system of region of origin and product quality.[80]
At the start of the 21st century, a two-tier structure has arisen, with a few international food processing giants controlling a wide range of well-known food brands. There also exists a wide array of small local or national food processing companies.[109] Advanced technologies have also come to change food manufacture. Computer-based control systems, sophisticated processing and packaging methods, and logistics and distribution advances can enhance product quality, improve food safety, and reduce costs.[108]
Some popular types of ethnic foods include Italian, French, Japanese, Chinese, American, Cajun, Thai, African, Indian and Nepalese. Various cultures throughout the world study the dietary analysis of food habits. While evolutionarily speaking, as opposed to culturally, humans are omnivores, religion and social constructs such as morality, activism, or environmentalism will often affect which foods they will consume. Food is eaten and typically enjoyed through the sense of taste, the perception of flavor from eating and drinking. Certain tastes are more enjoyable than others, for evolutionary purposes.

In addition, many cultures use grills for cooking. A grill operates with a radiant heat source from below, usually covered with a metal grid and sometimes a cover. An open pit barbecue in the American south is one example along with the American style outdoor grill fueled by wood, liquid propane, or charcoal along with soaked wood chips for smoking.[94] A Mexican style of barbecue is called barbacoa, which involves the cooking of meats such as whole sheep over an open fire. In Argentina, an asado (Spanish for "grilled") is prepared on a grill held over an open pit or fire made upon the ground, on which a whole animal or smaller cuts are grilled.[95]
The application of scientific knowledge to cooking and gastronomy has become known as molecular gastronomy. This is a subdiscipline of food science. Important contributions have been made by scientists, chefs and authors such as Herve This (chemist), Nicholas Kurti (physicist), Peter Barham (physicist), Harold McGee (author), Shirley Corriher (biochemist, author), Heston Blumenthal (chef), Ferran Adria (chef), Robert Wolke (chemist, author) and Pierre Gagnaire (chef).[44]
A negative-calorie food is food that supposedly requires more food energy to be digested than the food provides. Its thermic effect or specific dynamic action – the caloric "cost" of digesting the food – would be greater than its food energy content. Despite its recurring popularity in dieting guides, there is no scientific evidence supporting the idea that any food is calorically negative. While some chilled beverages are calorically negative, the effect is minimal[44] and drinking large amounts of water can be dangerous.

Food is any substance[1] consumed to provide nutritional support for an organism. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism and assimilated by the organism's cells to provide energy, maintain life, or stimulate growth.