Low-fat diet

Composition

According to the National Academies Press, 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 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

Main article: Saturated fat and cardiovascular disease

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 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 considering low-calorie diets. It also showed HDL increases and triglyceride decreases in high-fat diets. Furthermore, lower total cholesterol was associated with lower intake of saturated fat and higher intake of polyunsaturated fat, HDL increases were associated with high monounsaturated fat intake and triglycerides were 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 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 also decrease on low-fat diets. This indicates reduced androgen production, rather than increased androgen excretion on low-fat diets.

References

References

1. Makris A, Foster GD. "Dietary Approaches to the Treatment of Obesity". Psychiatr Clin North Am.
2. Food and nutrition board, institute of medicine of the national academies. (2005). "Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients)". National Academies Press.
3. (2017). "Obesity Pathogenesis: An Endocrine Society Scientific Statement.". Endocr Rev.
4. (December 2015). "Effect of low-fat diet interventions versus other diet interventions on long-term weight change in adults: a systematic review and meta-analysis". The Lancet. Diabetes & Endocrinology.
5. (1998). "Very low fat diets". Circulation.
6. Food and nutrition board, institute of medicine of the national academies. (2005). "Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients)". National Academies Press.
7. (Oct 17, 2014). "Comparison of effects of long-term low-fat vs high-fat diets on blood lipid levels in overweight or obese patients: a systematic review and meta-analysis.". [[Journal of the Academy of Nutrition and Dietetics]].
8. (2021). "Low-fat diets and testosterone in men: Systematic review and meta-analysis of intervention studies". The Journal of Steroid Biochemistry and Molecular Biology.
9. (2016). "Williams Textbook of Endocrinology". Elsevier.