Low-Fat Diet

Introduction

High-fat diets are associated with increased risk of several serious medical conditions including obesity, cancer, and heart disease. Consequently, current public health recommendations emphasize the importance of reducing total fat intake to no more than 30% of total calories, or 60 grams of fat per day in an 1800 calorie diet. Tips for reducing fat intake include lowering intake of whole fat dairy products, red meats, and high-fat condiments. While most people can improve their health by reducing the total amount of fat in their diet, the consumption of fat by children under the age of two should not be restricted. In addition, adults reducing their total fat intake should still be careful to include adequate amount of specific, essential fats, particularly the omega 3 fatty acids.

History

During the past 20 years, the amount and type of dietary fat that should be present in a healthy diet has been the source of tremendous controversy. Although fat is often portrayed as a dietary villain by the popular media, fat participates in five essential physiological functions.

  1. Fat serves as a source of energy for the body by supplying 9 calories per gram (compared to 4 calories per gram from carbohydrates and protein).
  2. Stored fat helps maintain body temperature and protects vital organs from injury.
  3. Dietary fat aids in the absorption and transport of the fat-soluble vitamins (A, D, E and K) and other fat-soluble nutrients.
  4. Fat improves the taste and mouth feel of food and provides a sense of satiety that helps us moderate how much food we eat at one time.
  5. Dietary fat provides two essential fatty acids (the omega 3 fat, alpha-linolenic acid, and the omega 6 fat, linoleic acid) both of which are necessary for a wide variety of important physiological processes.

Eating too much of the wrong kinds of fat, however, can increase our chances of becoming obese, or developing heart disease or cancer. As a result, various health and nutrition organizations, including the US Surgeon General, US Department of Health and Human Services, and the US Department of Agriculture favor a "low-fat" diet and have issued dietary recommendations that include reducing intake of total and saturated fat. In general, these guidelines suggest that for persons older than two years, total fat intake should not exceed more than 30% of total caloric intake and that saturated fat should account for no more than 10% of daily caloric intake. For total fat, this guideline means no more than 60 grams of fat per day on an 1800 calorie diet, and within that total fat, no more than 20 grams of saturated fat.

Popularity

With the growing recognition of the dangers of eating too much fat, and the plethora of "low-fat" and "fat-free" foods on the supermarket shelves, you would think that everyone in the United States is eating a low-fat diet. Unfortunately, recent statistics suggest that the opposite is true. According to the USDA's Continuing Survey of Food Intakes by Individuals, actual fat consumption has increased slightly over the past few decades, from approximately 81 grams per day in the late 1970s to about 83 grams per day in the early 1990s. In addition, results from the Third Report on Nutrition Monitoring in the United States indicate that a majority of the United States population fails to meet current recommendations for dietary fat consumption. In fact, only 21% and 25% of males and females 20 years old and older consume less than or equal to 30% of calories from fat. Children and adolescents are doing even worse than their parents at meeting current recommendations. Only about 18% of boys and girls aged 6 to 11 consume less than or equal to 30% of calories from fat, and only 14% and 18% of boys and girls, respectively, aged 12 to 19 meet current dietary recommendations for fat intake. The reason? Consumption of the major sources of dietary fat in the American diet, which include red meat, poultry, and dairy products (cheese, half and half, and ice cream) has not decreased, and consumption of high-fat snack foods, especially among children, is on the rise. All of this, despite the widespread availability of "low-fat" and "fat-free" food choices.

Principles

In general, any diet, regardless of the foods eaten, can be considered "low-fat" if it includes no more than 30% of total calories as fat, which is 60 grams of fat per day in an 1800 calorie diet. Consequently, there is no prescribed "low-fat" diet that mandates the exact foods that must be eaten. Some people choose to cut back on the amount of red meat they eat, while others avoid high-fat desserts, snack foods, condiments, or nuts. It is important to remember, however, that not every low-fat diet is necessarily a "healthy" diet. In fact, many people following a low-fat diet substitute foods that contain fat with "fat-free" processed foods that contain large amounts of sugar, salt, additives, and preservatives. So, what exactly can you do to develop a healthy, low-fat diet? Here are some tips for reducing your fat intake and promoting good health:

Label Terminology

When you're trying to lower your total fat intake, knowing the true meaning of those fat-related phrases on packaged foods will come in handy. Here's the low-down on label terminology:

Fat Chemistry

A final bit of information you may find helpful when trying to eat low-fat is a little insight into fat chemistry. You'll find many of the terms below on the ingredient lists of packaged foods. Knowing more about the different types of fat can help you improve the quality of the fats you consume, as well as help you lower your total fat intake.

Fats are composed of chains of carbon atoms, to which hydrogen and oxygen atoms are attached. Dietary fats are divided into different categories depending on the arrangement of hydrogen atoms in the carbon chain and the shape of the fat molecule. The four main categories of dietary fats are saturated fats, monounsaturated fats, polyunsaturated fats, and hydrogenated fats. Although foods almost always contain a mixture of different types of fats, foods that contain fat are typically classified by the type of fat that is most prevalent in the food. Here are some short profiles of these different types of fats:

Research

A significant amount of population-based research indicates that consumption of a diet high in total and saturated fat is associated with an increased risk for several medical conditions, such as obesity, heart disease, high blood pressure, insulin resistance, gallbladder disease, and certain cancers (for example, breast, colon, and prostate cancers).

On the other hand, critics of the "low-fat" craze argue that low-fat, high carbohydrate diets actually increase triglyceride levels and lower levels of HDL, the protective form of cholesterol. Research indicates that high triglyceride levels and low HDL levels are associated with an increased risk for heart disease.

Foods Emphasized

A healthy low-fat diet emphasizes the consumption of whole grains, beans, fruits, and vegetables, as well as small amounts of healthy sources of fat including raw nuts, raw seeds, vegetable oils (particularly monounsaturated oils like olive oil, and oils rich in omega 3 fats such as flaxseed oil and soybean oil), and cold water fish including salmon, herring, and mackerel.

Foods Avoided

Low-fat diets often exclude or limit red meats, whole fat dairy products (butter, milk, yogurt, heavy cream and ice cream), mayonnaise, margarine, and salad dressings. Extremely low-fat diets, such as the Dean Ornish diet and the Pritikin diet, eliminate nearly all animal products and added vegetable oils.

Nutrient Excesses/Deficiencies

Low-fat diets often contain a large amount of simple carbohydrates and refined sweeteners, especially when "low-fat" and "fat-free" processed foods are eaten. According to the USDA's 1995 Continuing Survey of Food Intakes by Individuals, the intake of sugar and other refined sweeteners increased from about 55 kg (120 lb) per person per year in 1970 to 68 kg (150 lb) per person per year in 1995. In addition, extremely low-fat diets may contain insufficient quantities of the omega 3 and omega 6 essential fatty acids.

Who Benefits

Fat is the most calorie-dense macronutrient (fat contains 9 calories per gram compared to 4 calories per gram for protein and carbohydrate), so foods containing fat are usually high in calories. If you are trying to lose weight by counting calories, reducing your consumption of high-fat foods can be beneficial. Also, if you have heart disease or cancer, or have a family history of either disease, your health may be improved by eating a diet that is low in total and saturated fat.

Who is Harmed

Following a low-fat diet (or a diet that contains fewer than 30% of calories as fat) is unlikely to cause any harm to healthy adults eating a varied and well-balanced diet, assuming they consume an adequate amount of essential fatty acids, especially the omega 3 fats. However, children require extra fat to maintain normal growth and development. As a result, the consumption of dietary fat by infants and children less than two years old should not be restricted.

Menu Ideas

Try a few of our favorite low-fat recipes.

Resources

For more information about how to cut the fat out of your diet, check out the following web pages:

References

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