Fat

Fat is one of the three main macronutrients, along with the other two: carbohydrate and protein.[1] Fats molecules consist of primarily carbon and hydrogen atoms, thus they are all hydrocarbon molecules. Examples include cholesterol, phospholipids and triglycerides.

The terms "lipid", "oil" and "fat" are often confused. "Lipid" is the general term, though a lipid is not necessarily a triglyceride. "Oil" normally refers to a lipid with short or unsaturated fatty acid chains that is liquid at room temperature, while "fat" (in the strict sense) may specifically refer to lipids that are solids at room temperature – however, "fat" (in the broad sense) may be used in food science as a synonym for lipid. Fats, like other lipids, are generally hydrophobic, and are soluble in organic solvents and insoluble in water.

Fat is an important foodstuff for many forms of life, and fats serve both structural and metabolic functions. They are a necessary part of the diet of most heterotrophs (including humans) and are the most energy dense, thus the most efficient form of energy storage.[2]

Some fatty acids that are set free by the digestion of fats are called essential because they cannot be synthesized in the body from simpler constituents. There are two essential fatty acids (EFAs) in human nutrition: alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid).[3][4] Other lipids needed by the body can be synthesized from these and other fats. Fats and other lipids are broken down in the body by enzymes called lipases produced in the pancreas.

Fats and oils are categorized according to the number and bonding of the carbon atoms in the aliphatic chain. Fats that are saturated fats have no double bonds between the carbons in the chain. Unsaturated fats have one or more double bonded carbons in the chain. The nomenclature is based on the non-acid (non-carbonyl) end of the chain. This end is called the omega end or the n-end. Thus alpha-linolenic acid is called an omega-3 fatty acid because the 3rd carbon from that end is the first double bonded carbon in the chain counting from that end. Some oils and fats have multiple double bonds and are therefore called polyunsaturated fats. Unsaturated fats can be further divided into cis fats, which are the most common in nature, and trans fats, which are rare in nature. Unsaturated fats can be altered by reaction with hydrogen effected by a catalyst. This action, called hydrogenation, tends to break all the double bonds and makes a fully saturated fat. To make vegetable shortening, then, liquid cis-unsaturated fats such as vegetable oils are hydrogenated to produce saturated fats, which have more desirable physical properties e.g., they melt at a desirable temperature (30–40 °C), and store well, whereas polyunsaturated oils go rancid when they react with oxygen in the air. However, trans fats are generated during hydrogenation as contaminants created by an unwanted side reaction on the catalyst during partial hydrogenation.

Saturated fats can stack themselves in a closely packed arrangement, so they can solidify easily and are typically solid at room temperature. For example, animal fats tallow and lard are high in saturated fatty acid content and are solids. Olive and linseed oils on the other hand are unsaturated and liquid. Fats serve both as energy sources for the body, and as stores for energy in excess of what the body needs immediately. Each gram of fat when burned or metabolized releases about 9 food calories (37 kJ = 8.8 kcal).[4] Fats are broken down in the healthy body to release their constituents, glycerol and fatty acids. Glycerol itself can be converted to glucose by the liver and so become a source of energy.

Trimyristin-3D-vdW
A fat, or triglyceride, molecule. Note the three fatty acid chains attached to the central glycerol portion of the molecule.
Fat composition in foods
Composition of fats from various foods, as percentage of their total fat.

Chemical structure

Triglyceride Structural Formulae V.1
Example of a natural triglyceride with three different fatty acids. One fatty acid is saturated (blue highlighted), another contains one double bond within the carbon chain (green highlighted). The third fatty acid (a polyunsaturated fatty acid, highlighted in red) contains three double bonds within the carbon chain. All carbon-carbon double bonds shown are cis isomers.

There are many different kinds of fats, but each is a variation on the same chemical structure. All fats are derivatives of fatty acids and glycerol. Most fats are glycerides, particularly triglycerides (triesters of glycerol). One chain of fatty acid is bonded to each of the three -OH groups of the glycerol by the reaction of the carboxyl end of the fatty acid (-COOH) with the alcohol; I.e. three chains per molecule. Water is eliminated and the carbons are linked by an -O- bond through dehydration synthesis. This process is called esterification and fats are therefore esters. As a simple visual illustration, if the kinks and angles of these chains were straightened out, the molecule would have the shape of a capital letter E. The fatty acids would each be a horizontal line; the glycerol "backbone" would be the vertical line that joins the horizontal lines. Fats therefore have "ester" bonds.

The properties of any specific fat molecule depend on the particular fatty acids that constitute it. Fatty acids form a family of compounds that are composed of increasing numbers of carbon atoms linked into a zig-zag chain (hydrogen atoms to the side). The more carbon atoms there are in any fatty acid, the longer its chain will be. Long chains are more susceptible to intermolecular forces of attraction (in this case, van der Waals forces), and so the longer ones melt at a higher temperature (melting point).

Examples of fatty acids.
trans Unsaturated (Example shown: Elaidic acid) cis Unsaturated (Example shown: Oleic acid) Saturated (Example shown: Stearic acid)
Elaidic-acid-3D-balls Oleic-acid-3D-ball-&-stick Stearic-acid-3D-balls
Elaidic acid is the principal trans unsaturated fatty acid often found in partially hydrogenated vegetable oils. Oleic acid is a cis unsaturated fatty acid making up 55–80% of olive oil. Stearic acid is a saturated fatty acid found in animal fats and is the intended product in full hydrogenation. Stearic acid is neither cis nor trans because it has no carbon-carbon double bonds.

Fatty acid chains may also differ by length, often categorized as short to very long.

  • Short-chain fatty acids (SCFA) are fatty acids with aliphatic tails of fewer than six carbons (i.e. butyric acid).
  • Medium-chain fatty acids (MCFA) are fatty acids with aliphatic tails of 6–12 carbons, which can form medium-chain triglycerides.
  • Long-chain fatty acids (LCFA) are fatty acids with aliphatic tails of 13 to 21 carbons.
  • Very long chain fatty acids (VLCFA) are fatty acids with aliphatic tails of 22 or more carbons.

Any of these aliphatic fatty acid chains may be glycerated and the resultant fats may have tails of different lengths from very short triformin to very long, e.g., cerotic acid, or hexacosanoic acid, a 26-carbon long-chain saturated fatty acid. Long chain fats are exemplified by tallow (lard) whose chains are 17 carbons long. Most fats found in food, whether vegetable or animal, are made up of medium to long-chain fatty acids, usually of equal or nearly equal length. Many cell types can use either glucose or fatty acids for this energy. In particular, heart and skeletal muscle prefer fatty acids. Despite long-standing assertions to the contrary, fatty acids can also be used as a source of fuel for brain cells.

Importance for living organisms

Fats are also sources of essential fatty acids, an important dietary requirement. They provide energy as noted above. Vitamins A, D, E, and K are fat-soluble, meaning they can only be digested, absorbed, and transported in conjunction with fats. Fats play a vital role in maintaining healthy skin and hair, insulating body organs against shock, maintaining body temperature, and promoting healthy cell function. Fat also serves as a useful buffer against a host of diseases. When a particular substance, whether chemical or biotic, reaches unsafe levels in the bloodstream, the body can effectively dilute—or at least maintain equilibrium of—the offending substances by storing it in new fat tissue. This helps to protect vital organs, until such time as the offending substances can be metabolized or removed from the body by such means as excretion, urination, accidental or intentional bloodletting, sebum excretion, and hair growth.

Adipose tissue

Fatmouse
The obese mouse on the left has large stores of adipose tissue. For comparison, a mouse with a normal amount of adipose tissue is shown on the right.

In animals, adipose tissue, or fatty tissue is the body's means of storing metabolic energy over extended periods of time. Adipocytes (fat cells) store fat derived from the diet and from liver metabolism. Under energy stress these cells may degrade their stored fat to supply fatty acids and also glycerol to the circulation. These metabolic activities are regulated by several hormones (e.g., insulin, glucagon and epinephrine). Adipose tissue also secretes the hormone leptin. [5]

The location of the tissue determines its metabolic profile: visceral fat is located within the abdominal wall (i.e., beneath the wall of abdominal muscle) whereas "subcutaneous fat" is located beneath the skin (and includes fat that is located in the abdominal area beneath the skin but above the abdominal muscle wall). Visceral fat was recently discovered to be a significant producer of signaling chemicals (i.e., hormones), among which several are involved in inflammatory tissue responses. One of these is resistin which has been linked to obesity, insulin resistance, and Type 2 diabetes. This latter result is currently controversial, and there have been reputable studies supporting all sides on the issue.

Fatty acids and human health

Dietary consumption of fatty acids has effects on human health. Studies have found that replacing saturated fats with cis unsaturated fats in the diet reduces risk of cardiovascular disease. For example, a 2015 systematic review of randomized control trials by the Cochrane Library concluded: "Lifestyle advice to all those at risk of cardiovascular disease and to lower risk population groups should continue to include permanent reduction of dietary saturated fat and partial replacement by unsaturated fats."[6]

Numerous studies have also found that consumption of trans fats increases risk of cardiovascular disease.[3][4] The Harvard School of Public Health advises that replacing trans fats and saturated fats with cis monounsaturated and polyunsaturated fats is beneficial for health.[7] a 2014 meta-analyses of randomized controlled trials found that reducing fat and cholesterol intake does not effect cardiovascular disease or all cause mortality.[8]

See also

References

  1. ^ "Macronutrients: the Importance of Carbohydrate, Protein, and Fat". McKinley Health Center. University of Illinois at Urbana–Champaign. Retrieved 20 September 2014.
  2. ^ "Introduction to Energy Storage". Khan Academy.
  3. ^ a b Mozaffarian, Dariush; Katan, Martijn B.; Ascherio, Alberto; Stampfer, Meir J.; Willett, Walter C. (2006-04-13). "Trans Fatty Acids and Cardiovascular Disease". New England Journal of Medicine. 354 (15): 1601–1613. doi:10.1056/NEJMra054035. ISSN 0028-4793. PMID 16611951.
  4. ^ a b c United Kingdom The Food Labelling Regulations 1996Schedule 7: Nutrition labelling
  5. ^ "The human proteome in adipose - The Human Protein Atlas". www.proteinatlas.org. Retrieved 2017-09-12.
  6. ^ Hooper, Lee; Martin, Nicole; Abdelhamid, Asmaa; Davey Smith, George (2015). "Reduction in saturated fat intake for cardiovascular disease". Cochrane Database of Systematic Reviews (6): CD011737. doi:10.1002/14651858.CD011737. PMID 26068959.
  7. ^ "Fats and Cholesterol", Harvard School of Public Health. Retrieved 02-11-16.
  8. ^ Harcombe, Zoë; Baker, Julien S.; Cooper, Stephen Mark; Davies, Bruce; Sculthorpe, Nicholas; Dinicolantonio, James J.; Grace, Fergal (2015). "Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis". Open Heart. 2: e000196. doi:10.1136/openhrt-2014-000196. PMID 25685363.

Further reading

Adipose tissue

In biology, adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular endothelial cells and a variety of immune cells such as adipose tissue macrophages. Adipose tissue is derived from preadipocytes. Its main role is to store energy in the form of lipids, although it also cushions and insulates the body. Far from being hormonally inert, adipose tissue has, in recent years, been recognized as a major endocrine organ, as it produces hormones such as leptin, estrogen, resistin, and the cytokine TNFα. The two types of adipose tissue are white adipose tissue (WAT), which stores energy, and brown adipose tissue (BAT), which generates body heat. The formation of adipose tissue appears to be controlled in part by the adipose gene. Adipose tissue – more specifically brown adipose tissue – was first identified by the Swiss naturalist Conrad Gessner in 1551.

Bacon

Bacon is a type of salt-cured pork. Bacon is prepared from several different cuts of meat, typically from the pork belly or from back cuts, which have less fat than the belly. It is eaten on its own, as a side dish (particularly in breakfasts), or used as a minor ingredient to flavour dishes (e.g., the club sandwich). Bacon is also used for barding and larding roasts, especially game, including venison and pheasant. The word is derived from the Old High German bacho, meaning "buttock", "ham" or "side of bacon", and is cognate with the Old French bacon.

Meat from other animals, such as beef, lamb, chicken, goat, or turkey, may also be cut, cured, or otherwise prepared to resemble bacon, and may even be referred to as, for example, "turkey bacon". Such use is common in areas with significant Jewish and Muslim populations as both religions prohibit the consumption of pork. Vegetarian bacons such as "soy bacon" also exist and attract vegetarians and vegans.

Chinese New Year

Chinese New Year (or generally referred to as Lunar New Year globally) is the Chinese festival that celebrates the beginning of a new year on the traditional Chinese calendar. The festival is usually referred to as the Spring Festival in mainland China, and is one of several Lunar New Years in Asia. Observances traditionally take place from the evening preceding the first day of the year to the Lantern Festival, held on the 15th day of the year. The first day of Chinese New Year begins on the new moon that appears between 21 January and 20 February. In 2019, the first day of the Chinese New Year was on Tuesday, 5 February, initiating the Year of the Pig.

Chinese New Year is a major holiday in Greater China and has strongly influenced lunar new year celebrations of China's neighbouring cultures, including the Korean New Year (seol), the Tết of Vietnam, and the Losar of Tibet. It is also celebrated worldwide in regions and countries with significant Overseas Chinese populations, including Singapore, Indonesia, Malaysia, Myanmar, Thailand, Cambodia, the Philippines, and Mauritius, as well as many in North America and Europe.Chinese New Year is associated with several myths and customs. The festival was traditionally a time to honour deities as well as ancestors. Within China, regional customs and traditions concerning the celebration of the New Year vary widely, and the evening preceding Chinese New Year's Day is frequently regarded as an occasion for Chinese families to gather for the annual reunion dinner. It is also traditional for every family to thoroughly clean their house, in order to sweep away any ill-fortune and to make way for incoming good luck. Another custom is the decoration of windows and doors with red paper-cuts and couplets. Popular themes among these paper-cuts and couplets include that of good fortune or happiness, wealth, and longevity. Other activities include lighting firecrackers and giving money in red paper envelopes. For the northern regions of China, dumplings are featured prominently in meals celebrating the festival.

Chow Yun-fat

Chow Yun-fat, SBS (born 18 May 1955), previously known as Patrick Chow, is a Hong Kong actor best known in Asia for his collaborations with filmmaker John Woo in the action heroic bloodshed-genre films A Better Tomorrow, The Killer, and Hard Boiled, and in the West for his roles as Li Mu-bai in Crouching Tiger, Hidden Dragon and Sao Feng in Pirates of the Caribbean: At World's End. He mainly plays in dramatic films and has won three Hong Kong Film Awards for Best Actor and two Golden Horse Awards for Best Actor in Taiwan.

In 2014, Chow was the second-highest earning actor in Hong Kong, earning HK$170 million (US$21.9 million). His reported net worth is HK$5.6 billion (US$714 million).

Coconut oil

Coconut oil, or copra oil, is an edible oil extracted from the kernel or meat of mature coconuts harvested from the coconut palm (Cocos nucifera). It has various applications. Because of its high saturated fat content, it is slow to oxidize and, thus, resistant to rancidification, lasting up to six months at 24 °C (75 °F) without spoiling.Due to its high levels of saturated fat, the World Health Organization, the United States Department of Health and Human Services, United States Food and Drug Administration, American Heart Association, American Dietetic Association, British National Health Service, British Nutrition Foundation, and Dietitians of Canada advise that coconut oil consumption should be limited or avoided.

Fat Joe

Joseph Antonio Cartagena (born August 19, 1970), better known by his stage name Fat Joe, is an American rapper and actor from the Bronx, New York. He began his music career as a member of hip hop group Diggin' in the Crates Crew (D.I.T.C.), then forged a solo career and set up his own label, Terror Squad, to which he signed Big Pun, Remy Ma, Tony Sunshine, Cuban Link, Armageddon, Prospect, Triple Seis and DJ Khaled as well as discover producers Cool & Dre.

Fat Joe's debut solo album, Represent, was released in 1993 and spawned the single "Flow Joe", which reached number one on the Billboard Hot Rap Songs. His most commercially successful album to date was Jealous Ones Still Envy (J.O.S.E.) (2001); it was certified platinum by the RIAA and internationally certified silver by the BPI, as well as reaching the top 100 on multiple music charts.

He is best known for the songs "Lean Back" with Terror Squad, "What's Luv?" featuring Ashanti & Ja Rule, "Make It Rain" featuring Lil Wayne and "All the Way Up" with Remy Ma featuring French Montana and Dre.

Fat Joe has appeared in several films, including Scary Movie 3 and Happy Feet, as well as Spike Lee's Netflix series She’s Gotta Have It.In 2018 he began hosting a podcast on Tidal, Coca Vision, where he discusses music, friendships, and pop culture with some of the industry's most entertaining voices. He has an upcoming album called Family Ties which is scheduled to be released in late 2019.

Fat Man

"Fat Man" was the codename for the nuclear bomb that was detonated over the Japanese city of Nagasaki by the United States on 9 August 1945. It was the second of the only two nuclear weapons ever used in warfare, the first being Little Boy, and its detonation marked the third nuclear explosion in history. It was built by scientists and engineers at Los Alamos Laboratory using plutonium from the Hanford Site, and it was dropped from the Boeing B-29 Superfortress Bockscar piloted by Major Charles Sweeney.

The name Fat Man refers to the early design of the bomb because it had a wide, round shape; it was also known as the Mark III. Fat Man was an implosion-type nuclear weapon with a solid plutonium core. The first of that type to be detonated was the Gadget in the Trinity nuclear test less than a month earlier on 16 July at the Alamogordo Bombing and Gunnery Range in New Mexico. Two more were detonated during the Operation Crossroads nuclear tests at Bikini Atoll in 1946, and some 120 were produced between 1947 and 1949, when it was superseded by the Mark 4 nuclear bomb. The Fat Man was retired in 1950.

File Allocation Table

File Allocation Table (FAT) is a computer file system architecture and a family of industry-standard file systems utilizing it. The FAT file system is a continuing standard which borrows source code from the original, legacy file system and proves to be simple and robust. It offers useful performance even in lightweight implementations, but cannot deliver the same performance, reliability and scalability as some modern file systems. It is, however, supported for compatibility reasons by nearly all currently developed operating systems for personal computers and many mobile devices and embedded systems, and thus is a well-suited format for data exchange between computers and devices of almost any type and age from 1981 up to the present.

Originally designed in 1977 for use on floppy disks, FAT was soon adapted and used almost universally on hard disks throughout the DOS and Windows 9x eras for two decades. As disk drives evolved, the capabilities of the file system have been extended accordingly, resulting in three major file system variants: FAT12, FAT16 and FAT32. The FAT standard has also been expanded in other ways while generally preserving backward compatibility with existing software.

With the introduction of more powerful computers and operating systems, as well as the development of more complex file systems for them, FAT is no longer the default file system for usage on Microsoft Windows computers.FAT file systems are still commonly found on floppy disks, flash and other solid-state memory cards and modules (including USB flash drives), as well as many portable and embedded devices. FAT is the standard file system for digital cameras per the DCF specification.

Gabriel Iglesias

Gabriel Jesus Iglesias (born July 15, 1976), known comically as Fluffy, is an American comedian, actor, writer, producer and voice actor. He is known for his shows I'm Not Fat… I'm Fluffy and Hot & Fluffy.

Joey Fatone

Joseph Anthony Fatone Jr. (born January 28, 1977) is an American singer, dancer, actor, and television personality. He is best known as a member of the boyband NSYNC, in which he sang baritone. In 2007, he came in second place on the ABC reality show Dancing with the Stars. He was the host of the U.S. and Australian versions of The Singing Bee, which aired on NBC in the U.S. Fatone was also the announcer for the game show Family Feud from 2010 to 2015. Fatone previously hosted on Food Network's Rewrapped, Live Well Network's My Family Recipe Rocks, and The Price Is Right Live! at Bally's Las Vegas.

Lipid

In biology and biochemistry, a lipid is a biomolecule that is soluble in nonpolar solvents. Non-polar solvents are typically hydrocarbons used to dissolve other naturally occurring hydrocarbon lipid molecules that do not (or do not easily) dissolve in water, including fatty acids, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, and phospholipids.

The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries as well as in nanotechnology.Scientists sometimes broadly define lipids as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, multilamellar/unilamellar liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks": ketoacyl and isoprene groups. Using this approach, lipids may be divided into eight categories: fatty acids, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, and polyketides (derived from condensation of ketoacyl subunits); and sterol lipids and prenol lipids (derived from condensation of isoprene subunits).Although the term "lipid" is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides. Lipids also encompass molecules such as fatty acids and their derivatives (including tri-, di-, monoglycerides, and phospholipids), as well as other sterol-containing metabolites such as cholesterol. Although humans and other mammals use various biosynthetic pathways both to break down and to synthesize lipids, some essential lipids can't be made this way and must be obtained from the diet.

Mardi Gras

Mardi Gras (), or Fat Tuesday, refers to events of the Carnival celebration, beginning on or after the Christian feasts of the Epiphany (Three Kings Day) and culminating on the day before Ash Wednesday (known as Shrove Tuesday). Mardi Gras is French for "Fat Tuesday", reflecting the practice of the last night of eating rich, fatty foods before the ritual fasting of the Lenten season.

Related popular practices are associated with Shrovetide celebrations before the fasting and religious obligations associated with the penitential season of Lent. In countries such as the United Kingdom, Mardi Gras is also known as Shrove Tuesday, which is derived from the word shrive, meaning "to administer the sacrament of confession to; to absolve".

Milk

Milk is a nutrient-rich, white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for infant mammals (including humans who are breastfed) before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to its young and can reduce the risk of many diseases. It contains many other nutrients including protein and lactose. Interspecies consumption of milk is not uncommon, particularly among humans, many of whom consume the milk of other mammals.As an agricultural product, milk, also called dairy milk, is extracted from farm animals during or soon after pregnancy. Dairy farms produced about 730 million tonnes of milk in 2011, from 260 million dairy cows. India is the world's largest producer of milk, and is the leading exporter of skimmed milk powder, yet it exports few other milk products. The ever increasing rise in domestic demand for dairy products and a large demand-supply gap could lead to India being a net importer of dairy products in the future. The United States, India, China and Brazil are the world's largest exporters of milk and milk products. China and Russia were the world's largest importers of milk and milk products until 2016 when both countries became self-sufficient, contributing to a worldwide glut of milk.Throughout the world, more than six billion people consume milk and milk products. Over 750 million people live in dairy farming households.

Obesity

Obesity is a medical condition in which excess body fat has accumulated to an extent that it may have a negative effect on health. People are generally considered obese when their body mass index (BMI), a measurement obtained by dividing a person's weight by the square of the person's height, is over 30 kg/m2; the range 25–30 kg/m2 is defined as overweight. Some East Asian countries use lower values. Obesity increases the likelihood of various diseases and conditions, particularly cardiovascular diseases, type 2 diabetes, obstructive sleep apnea, certain types of cancer, osteoarthritis, and depression.Obesity is most commonly caused by a combination of excessive food intake, lack of physical activity, and genetic susceptibility. A few cases are caused primarily by genes, endocrine disorders, medications, or mental disorder. The view that obese people eat little yet gain weight due to a slow metabolism is not medically supported. On average, obese people have a greater energy expenditure than their normal counterparts due to the energy required to maintain an increased body mass.Obesity is mostly preventable through a combination of social changes and personal choices. Changes to diet and exercising are the main treatments. Diet quality can be improved by reducing the consumption of energy-dense foods, such as those high in fat or sugars, and by increasing the intake of dietary fiber. Medications can be used, along with a suitable diet, to reduce appetite or decrease fat absorption. If diet, exercise, and medication are not effective, a gastric balloon or surgery may be performed to reduce stomach volume or length of the intestines, leading to feeling full earlier or a reduced ability to absorb nutrients from food.Obesity is a leading preventable cause of death worldwide, with increasing rates in adults and children. In 2015, 600 million adults (12%) and 100 million children were obese in 195 countries. Obesity is more common in women than men. Authorities view it as one of the most serious public health problems of the 21st century. Obesity is stigmatized in much of the modern world (particularly in the Western world), though it was seen as a symbol of wealth and fertility at other times in history and still is in some parts of the world. In 2013, the American Medical Association classified obesity as a disease.

Saturated fat

A saturated fat is a type of fat in which the fatty acid chains have all or predominantly single bonds. A fat is made of two kinds of smaller molecules: glycerol and fatty acids. Fats are made of long chains of carbon (C) atoms. Some carbon atoms are linked by single bonds (-C-C-) and others are linked by double bonds (-C=C-). Double bonds can react with hydrogen to form single bonds. They are called saturated, because the second bond is broken and each half of the bond is attached to (saturated with) a hydrogen atom. Most animal fats are saturated. The fats of plants and fish are generally unsaturated. Saturated fats tend to have higher melting points than their corresponding unsaturated fats, leading to the popular understanding that saturated fats tend to be solids at room temperatures, while unsaturated fats tend to be liquid at room temperature with varying degrees of viscosity (meaning both saturated and unsaturated fats are found to be liquid at body temperature).

Various fats contain different proportions of saturated and unsaturated fat. Examples of foods containing a high proportion of saturated fat include animal fat products such as cream, cheese, butter, other whole milk dairy products and fatty meats which also contain dietary cholesterol. Certain vegetable products have high saturated fat content, such as coconut oil and palm kernel oil. Many prepared foods are high in saturated fat content, such as pizza, dairy desserts, and sausage.Guidelines released by many medical organizations including the World Health Organization have advocated for reduction in the intake of saturated fat to promote health and reduce the risk from cardiovascular diseases. Many review articles also recommend a diet low in saturated fat and argue it will lower risks of cardiovascular diseases, diabetes, or death. However, a smaller number of other reviews have come to different conclusions.

Trans fat

Trans fat, also called trans-unsaturated fatty acids or trans fatty acids, is a type of unsaturated fat that occurs in small amounts in nature, but became widely produced industrially from vegetable fats starting in the 1950s for use in margarine, snack food, packaged baked goods, and for frying fast food.Fats contain long hydrocarbon chains, which can be either unsaturated, i.e., have double bonds, or saturated, i.e., have no double bonds. In nature, unsaturated fatty acids generally have cis as opposed to trans configurations. In food production, liquid cis-unsaturated fats such as vegetable oils are hydrogenated to produce saturated fats, which have more desirable physical properties, e.g., they melt at a desirable temperature (30–40 °C). Partial hydrogenation of the unsaturated fat converts some of the cis double bonds into trans double bonds by an isomerization reaction with the catalyst used for the hydrogenation, which yields a trans fat.Although trans fats are edible, consuming trans fats has been shown to increase the risk of coronary artery disease in part by raising levels of low-density lipoprotein (LDL, often termed "bad cholesterol"), lowering levels of high-density lipoprotein (HDL, often termed "good cholesterol"), increasing triglycerides in the bloodstream and promoting systemic inflammation.Trans fats also occur naturally, e.g., vaccenic acid and some isomers of conjugated linoleic acid (CLA). These trans fats occur naturally in meat and dairy products from ruminants. Butter, for example, contains about 3% trans fat. Two Canadian studies have shown that vaccenic acid could be beneficial compared to hydrogenated vegetable shortening, or a mixture of pork lard and soy fat, by lowering total LDL and triglyceride levels. A study by the US Department of Agriculture showed that vaccenic acid raises both HDL and LDL cholesterol, whereas industrial trans fats only raise LDL with no beneficial effect on HDL.In light of recognized evidence and scientific agreement, nutritional authorities consider all trans fats equally harmful for health and recommend that their consumption be reduced to trace amounts. The World Health Organization recommended that trans fats make up no more than 1% of a person's diet in 2003 and, in 2018, introduced a 6-step guide to eliminate industrially-produced trans-fatty acids from the global food supply.In many countries, there are legal limits to trans fat content. Trans fats levels can be reduced or eliminated using saturated fats such as lard, palm oil, or fully hydrogenated fats, or by using interesterified fat. Other alternative formulations can also allow unsaturated fats to be used to replace saturated or partially hydrogenated fats. Hydrogenated oil is not a synonym for trans fat: complete hydrogenation removes all unsaturated fats.

Vegetable oil

Vegetable oils, or vegetable fats, are fats extracted from seeds, or less often, from other parts of fruits. Like animal fats, vegetable fats are mixtures of triglycerides. Soybean oil, rapeseed oil, and cocoa butter are examples of fats from seeds. Olive oil, palm oil, and rice bran oil are example of fats from other parts of fruits. In common usage, vegetable oil may refer exclusively to vegetable fats which are liquid at room temperature.

Vitamin

A vitamin is an organic molecule (or related set of molecules) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through the diet. Vitamin C can be synthesized by some species but not by others; it is not a vitamin in the first instance but is in the second. The term vitamin does not include the three other groups of essential nutrients: minerals, essential fatty acids, and essential amino acids. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, vitamin E consists of four tocopherols and four tocotrienols. The thirteen vitamins required by human metabolism are: vitamin A (retinols and carotenoids), vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid), vitamin B6 (pyridoxine), vitamin B7 (biotin), vitamin B9 (folic acid or folate), vitamin B12 (cobalamins), vitamin C (ascorbic acid), vitamin D (calciferols), vitamin E (tocopherols and tocotrienols), and vitamin K (quinones).

Vitamins have diverse biochemical functions. Some forms of vitamin A function as regulators of cell and tissue growth and differentiation. The B complex vitamins function as enzyme cofactors (coenzymes) or the precursors for them. Vitamin D has a hormone-like function as a regulator of mineral metabolism for bones and other organs. Vitamins C and E function as antioxidants. Both deficient and excess intake of a vitamin can potentially cause clinically significant illness, although excess intake of water-soluble vitamins is less likely to do so.

Before 1935, the only source of vitamins was from food. If intake of vitamins was lacking, the result was vitamin deficiency and consequent deficiency diseases. Then, commercially produced tablets of yeast-extract vitamin B complex and semi-synthetic vitamin C became available. This was followed in the 1950s by the mass production and marketing of vitamin supplements, including multivitamins, to prevent vitamin deficiencies in the general population. Governments mandated addition of vitamins to staple foods such as flour or milk, referred to as food fortification, to prevent deficiencies. Recommendations for folic acid supplementation during pregnancy reduced risk of infant neural tube defects. Although reducing incidence of vitamin deficiencies clearly has benefits, supplementation is thought to be of little value for healthy people who are consuming a vitamin-adequate diet.The term vitamin is derived from the word vitamine, coined in 1912 by Polish biochemist Casimir Funk, who isolated a complex of micronutrients essential to life, all of which he presumed to be amines. When this presumption was later determined not to be true, the "e" was dropped from the name. All vitamins were discovered (identified) between 1913 and 1948.

Weight loss

Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue or lean mass, namely bone mineral deposits, muscle, tendon, and other connective tissue. Weight loss can either occur unintentionally due to malnourishment or an underlying disease or arise from a conscious effort to improve an actual or perceived overweight or obese state. "Unexplained" weight loss that is not caused by reduction in calorific intake or exercise is called cachexia and may be a symptom of a serious medical condition. Intentional weight loss is commonly referred to as slimming.

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