Know Your Fats by Mary Enig
Book Review

Know Your Fats by biochemist and nutritionist Mary Enig is subtitled: A Complete Primer For Understanding the Nutrition of Fats, Oils and Cholesterol. Besides outlining the biochemistry of fats and oils, the book gives a spirited defense of saturated fats and a no-holds-barred expose of trans fats.

Mary Enig has been instrumental in exposing the dangers of trans fats to the public. She is a co-founder of the Weston A. Price Foundation and has collaborated with Sally Fallon on Nourishing Traditions, Eat Fat Lose Fat, and other projects.

Enig's stated purpose for this book is to provide accurate information; she comments that popular works on fats, and sometimes even technical works, are frequently inaccurate. She provides a lot of technical information here, including a brief catalog of the food sources of fats and oils.

Her main points may perhaps be stated this way:

  • The body has uses for all the variety of naturally occurring fats and oils in food.
  • Some natural fats and oils have special health benefits.
  • A few components of some of the natural fats and oils are scientifically considered essential to bodily processes.
  • The trans fats, which are industrially manufactured, actually interfere with bodily processes.

Recommendations often are made about how much fat and what kind of fat to eat. These may advise a certain percentage of calories from fat and specify proportions of the different categories of fatty acids (saturated, monounsaturated, polyunsaturated, and trans fats). What data are these recommendations based on?

For researchers to discover the relationship between fat and disease, or any other effects of fat, they must first be able to measure the amount of fat in individual diets. To do this, they need food tables of the fat content of natural foods such as meats, nuts, and fish. They also need information on the fat content on processed foods, of the kind that would appear on a food label.

Enig gives evidence that researchers have had neither accurate food tables nor accurate labels. As a lipid (fats and oils) biochemist at the University of Maryland's Lipids Research Laboratory, Enig's work included the laboratory analysis of common foods. (Appended to the book are the University of Maryland's tables of the fat analysis of dairy foods, oils, nuts, seeds, meats, and fish.) From her experience, Enig remarks that the food tables that have been used to give dietary advice are incorrect, outdated, and never revised for accuracy.

And when her lab analyzed processed foods and compared the analyses to the labels, food labels were found to be wildly inaccurate and misleading, often specifically in a way in which the only possible conclusion would be that the food processing company was hiding trans fat.

Why is this important? Hidden trans fat is not a minor matter. Some 50% of the calories most of us eat are from processed foods. The fat in today's processed foods are almost entirely the vegetable oils: corn, soybean, canola, and cottonseed. Enig writes that 70% of the vegetable oils in processed foods are partially hydrogenated, and partially hydrogenated vegetable oils contain up to 60% trans fat.

Thus the amount of trans fat in a realistic American diet must be large, at least 42% of all of the fat from processed foods.

There is no substitute for the information found in Know Your Fats. Unfortunately, however, it is not particularly user-friendly. It is neither wholly a popular book--it is too dry--nor wholly a reference book--it is too difficult to find specific information. It is almost like notes for a more user-friendly book that could have been written. 

The Fats of Life by Caroline Pond—which has a completely different purpose and does not give advice on diet—is much clearer on how fats are used in the body.

However, I recommend Know Your Fats highly for what can be found nowhere else. 

See Know Your Fats on Amazon

See The Fats of Life on Amazon