低脂飲食

Definition

定義

Different medical organizations, governments, and diet plans define "low fat" in slightly different ways. In general, a low-fat diet is one where 30% or less of the total daily calories come from fats. A very low-fat diet is one where 15% or less of the total daily calories come from fat. By comparison, in the average American diet about 35%-37% of calories come from fat.

不同的醫療機構、政府和飲食計劃都對"低脂"有不同的定義，但差別不大。總的來說，低脂飲食是指每天攝入的卡路里總量只有30%或以下來源於脂肪。脂肪量很低的飲食是指每天攝入的卡路里總量只有15%或以下來源於脂肪。相比之下，美國人平均飲食中有35%-37%的卡路里來源於脂肪。

Origins

起源

When metabolized in the body, fats provide 9 calories per gram compared to 4 calories per gram from proteins and carbohydrates. Because of this, diet plans repeatedly target reduction in fats as a good way to lose weight. Examples of low-fat diets include the Pritikin diet and Scarsdale diet, both popular in the 1970s, Rosemary Conley's Hip and Thigh Diet (late 1980s), and the Dr. Dean Ornish Diet (2000s). Research into preventing cardiovascular disease also stimulated interest in low-fat diets as a preventative health measure.

當在身體中代謝時，每克脂肪提供9卡，而每克蛋白質和碳水化合物提供4卡。因此，飲食計劃反覆將減少脂肪作爲減肥的好方法。低脂飲食包括在20世紀70年代十分風靡的普里特金低脂飲食和斯卡斯代爾低脂飲食、羅斯瑪麗臀部和大腿飲食（20世紀80年代末）以及歐尼許節食法（21世紀初）。有關預防心血管疾病的研究也推動了人們對低脂飲食的興趣，可將其作爲預防性的健康措施。

Description

描述

Fats are described as either saturated or unsaturated based on their chemical structure. Saturated fats are found in animal fats such as butter, the fats in milk and cream, bacon fat, the fat under the skin of chickens, lard, or the fat on a piece of prime rib of beef. These fats are usually solid at room temperature. Exceptions are palm oil and coconut oil, which are both liquid saturated fats. Saturated fats are often referred to as the "bad" fats. When consumed in high amounts, they raise the level of LDL cholesterol ("bad" cholesterol) in the blood. High LDL cholesterol levels are associated with an increased risk of heart disease.

基於脂肪的化學構造，人們將其描述爲飽和脂肪或不飽和脂肪。黃油等動物類脂肪、牛奶和奶油中的脂肪、培根脂肪、雞肉皮下脂肪、豬油或是牛上肋的脂肪都屬於飽和脂肪。通常這些脂肪在室溫下呈固體狀態。飽和脂肪經常被稱爲"壞"脂肪。當攝入大量飽和脂肪時，血液中低密度脂蛋白膽固醇（"壞"膽固醇）的水平會升高。高水平的低密度脂蛋白膽固醇與心臟病風險增加相關。

Unsaturated fats have a slightly different chemical structure that makes them liquid at room temperature. Unsaturated fats, especially monounsaturated fats, are considered "good" fats that can help lower cholesterol levels. Olive oil, canola oil, and peanut oil are high in monounsaturated fats. Corn oil, soybean oil, safflower oil, and sunflower oil are high in polyunsaturated fats. Fish oils are a rich source of two particular polyunsaturated fats termed long-chain omega-3 fatty acids, which have beneficial health effects.

不飽和脂肪的化學構造與其略有不同，使它們在室溫下呈液體狀態。不飽和脂肪，尤其是單一不飽和脂肪被認爲是"好"脂肪，能有助於降低膽固醇水平。橄欖油、菜籽油和花生油富含單一不飽和脂肪。玉米油、大豆油、紅花油和葵花籽油富含多元不飽和脂肪。魚油是兩種特別的稱爲長鏈歐米茄3脂肪酸的多元不飽和脂肪的豐富來源，這種脂肪有健康益處。