Critique of the book “You Are What You Eat”

This answer is brought to you by many of the Australian nutrition professionals who regularly contribute to a nutrition email discussion group. Date of last update: Jan 2005

A book entitled You Are What You Eat , by Dr Gillian McKeith, made its way onto the best-seller list in Australia in 2004. The book has also been used as the basis for a television program of the same name, shown on the Nine Network in Australia.

Although some of the advice given by McKeith coincides with current orthodox nutritional science, the vast majority of her ideas about the relationships between nutrition and health have no scientific basis whatsoever.

As just one example, she claims that “one of the most alarming studies by medical researchers found that a diet full of cooked foods may cause the reduction of brain tissue and the swelling of the key organs.”

This is simply not correct—far from harming people, or reducing the nutritional value of food, cooking makes many foods (especially starchy plant foods) easier to digest—have you ever tried to eat raw potato, uncooked meat or grains of wheat? Cooking also renders some otherwise toxic foods edible. For example, beans—which contain heat-labile toxins known as ‘lectins'—are very nutritious, but are unsafe to eat in large quantities unless they have been cooked (thereby destroying the lectins). Cooking can also release beneficial chemicals in some foods. A good example is lycopene, an antioxidant that is strongly associated with improved health. Lycopene is present in larger quantities in tomato paste, tomato sauce and other cooked forms of tomato than in the fresh fruit. Finally, cooking kills bacteria and other micro-organisms that can cause food poisoning, thereby making food safer to eat.

McKeith also advises that “you drink at least eight glasses of filtered, spring, or mineral water every day”. An FAQ in this series points out that there is no reason why anyone should always aim to drink this much water. Direct URL for the FAQ:

http://www.nutritionaustralia.org/Food_Facts/FAQ/optimal_hydration_faq.asp

Similarly, her belief that you should “drink water approximately 25 minutes before eating your main meals, instead of drinking with meals” is not supported by another Nut-Net FAQ; direct URL:

http://www.nutritionaustralia.org/Food_Facts/FAQ/drinks_meals2_faq.asp

Occasionally McKeith's ideas do accord with orthodox nutritional science. She is correct in stating that “a diet high in fat (particularly saturated fat) and high in salt is associated with increased risk of coronary heart disease”, and also that “carrying excess weight doesn't just increase the risk of heart disease, diabetes, cancer and infertility, it is also associated with fatigue, low self-esteem and poor mental and physical performance.” She also (appropriately) advocates eating more whole-grain cereals, fruits and vegetables, and she recommends moderately-vigorous physical activity.

But for the most part, Gillian McKeith is astonishingly ignorant of basic nutritional and medical science. So, although she advocates eating fresh fruits and vegetables, she claims that cooking them “destroys all the life-enhancing enzymes”, which she believes are “the life force of food and help the digestion process.” This is not correct: enzymes in raw foods are treated by the digestive system in the same way as proteins generally. They are denatured in the acid environment of the stomach and then digested into their constituent amino acids by the digestive enzymes we produce in our stomach and pancreas. These amino acids are then absorbed from the small intestine and transported in the blood to wherever they are needed, so the body can reassemble them into its own proteins (including enzymes).

In summary, the ideas in Gillian McKeith's book and television program You Are What You Eat are a complex mixture of orthodox nutrition, misinterpretations of orthodox nutrition, new-age wishful thinking, Eastern (especially traditional Chinese) medicine and reflexology . Her teachings are generally diametrically opposed to those of current, science-based nutrition and she is not a reliable source of information on how diet can benefit health.

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Disclaimer: This material is provided on the basis that it constitutes advice of a general nature only. It is not intended to replace the advice of a physician or a dietitian.