A low-fat diet is one that restricts fat, and often

saturated fat A saturated fat is a type of fat in which the fatty acid chains have all single bonds. A fat known as a glyceride is made of two kinds of smaller molecules: a short glycerol backbone and fatty acids that each contain a long linear or branche ...

and

cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell memb ...

as well. Low-fat diets are intended to reduce the occurrence of conditions such as

heart disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, h ...

and obesity. For weight loss, they perform similarly to a

low-carbohydrate diet Low-carbohydrate diets restrict carbohydrate consumption relative to the average diet. Foods high in carbohydrates (e.g., sugar, bread, pasta) are limited, and replaced with foods containing a higher percentage of fat and protein (e.g., meat, ...

, since

macronutrient A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excr ...

composition does not determine weight loss success. Fat provides nine calories per gram while carbohydrates and protein each provide four calories per gram. The

Institute of Medicine The National Academy of Medicine (NAM), formerly called the Institute of Medicine (IoM) until 2015, is an American nonprofit, non-governmental organization. The National Academy of Medicine is a part of the National Academies of Sciences, Eng ...

recommends limiting fat intake to 35% of total calories to control saturated fat intake.

Composition

According to the ''

National Academies Press The US National Academies Press (NAP) was created to publish the reports issued by the National Academies of Sciences, Engineering, and Medicine, the National Academy of Engineering, the National Academy of Medicine, and the National Research ...

'', a high-fat diet can contain "unacceptably high" amounts of saturated fat, even if saturated fats from animal products and tropical oils are avoided. This is because all fats contain some saturated fatty acids. For example, if a person chose fats with only 20% saturated fatty acids, setting fat intake at 35% of total calories would mean that 7% of calories would come from saturated fat. For this reason, the Institute of Medicine recommends consuming no more than 35% of calories from fat.

Health effects

Body weight

Studies have shown that the effectiveness of low-fat diets for weight loss is broadly similar to that of low-carbohydrate diets in the long-term. A scientific panel for the

Endocrine Society The Endocrine Society is a professional, international medical organization in the field of endocrinology and metabolism, founded in 1916 as The Association for the Study of Internal Secretions. The official name of the organization was changed ...

stated that "when calorie intake is held constant ..body-fat accumulation does not appear to be affected by even very pronounced changes in the amount of fat vs carbohydrate in the diet."

Cardiovascular health

Low-fat diets have been promoted for the prevention of heart disease. Lowering fat intake from 35 to 40% of total calories to 15-20% of total calories has been shown to decrease total and

LDL cholesterol Low-density lipoprotein (LDL) is one of the five major groups of lipoprotein that transport all fat molecules around the body in extracellular water. These groups, from least dense to most dense, are chylomicrons (aka ULDL by the overall densi ...

by 10 to 20%; however, most of this decrease is due to a reduction in saturated fat intake. Saturated fat has been shown to raise total and LDL cholesterol in a large number of studies and has also been correlated with a higher risk of heart disease. A 2013 meta-analysis of low- and high-fat diets showed low-fat diets decreased total cholesterol and LDL, but these decreases were not found when only considering low-calorie diets. It also showed HDL increases and

triglyceride A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from ''tri-'' and ''glyceride''). Triglycerides are the main constituents of body fat in humans and other vertebrates, as ...

decreases in high-fat diets. Furthermore, lower total cholesterol was associated with lower intake of saturated fat and higher intake of

polyunsaturated fat Polyunsaturated fats are fats in which the constituent hydrocarbon chain possesses two or more carbon–carbon double bonds. Polyunsaturated fat can be found mostly in nuts, seeds, fish, seed oils, and oysters. "Unsaturated" refers to the fact t ...

, HDL increases were associated with high monounsaturated fat intake and

s associated with high carbohydrate intake. Decrease in saturated fat intake was only marginally related to decrease in LDL cholesterol. The meta-analysis concluded that neither high-fat nor low-fat diets could be unequivocally recommended.

Testosterone

There is limited evidence that low-fat diets compared to high-fat diets, decreased men's total and free

testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...

levels. The decrease in testosterone on low-fat diets is thought to be due to a decrease in testicular testosterone synthesis, since both urinary testosterone and

dihydrotestosterone Dihydrotestosterone (DHT, 5α-dihydrotestosterone, 5α-DHT, androstanolone or stanolone) is an endogenous androgen sex steroid and hormone. The enzyme 5α-reductase catalyzes the formation of DHT from testosterone in certain tissues includi ...

also decrease on low-fat diets. This indicates reduced androgen production, rather than increased androgen excretion on low-fat diets.

References

External links

American Heart Association: FatsBritish Heart Foundation: Fats Explained pageNHS Choices: Fat - the facts
{{DEFAULTSORT:Low-fat diet Diets