Extreme Diets: Fads and Facts

Steven Rourke; Reviewed by Anya Romanowski, MS, RD


May 21, 2018

The Stone Age and Paleolithic Diets

Recent interest in eating like our prehistoric ancestors surfaced in 1975, when the gastroenterologist Walter Voegtlin, MD, proposed the "Stone Age diet," which featured meats, animal fats, and plants but eliminated dairy and grains.[31,32] In the 1980s, Stanley Boyd Eaton, MD, published his interpretation of a prehistoric, East African diet, which proposed a similar menu.[31] Other researchers have explored the health benefits of the traditional Inuit diet.[33]

But popular interest in "prehistoric diets" took off in 2002 when Loren Cordain, PhD, a professor of health and exercise sciences, published The Paleo Diet.[34,35] This high-protein diet includes lean meats, fish, fruit, vegetables, some animal fats, eggs, and seeds, while avoiding processed foods, wheat, dairy, grains, legumes, sugar, salt, and potatoes.[34] Eating like hunter-gatherers—a diet to which he argues we are genetically adapted[36]—is, according to Cordain, a means to slim down while preventing diabetes, heart disease, and cancer.[34]

Despite a critical absence of calcium, the diet has shown potential advantages in the reduction of type 2 diabetes and cardiovascular risk[36] and is one of the many high-protein, low-carbohydrate diets that continue to gather traction.

The Fit for Life Diet

The Fit for Life diet was first marketed in 1985 by "nutrition specialists"[37] Harvey and Marilyn Diamond. On the diet, Harvey Diamond "overcame a debilitating, longtime digestive disorder, ended his migraine headaches, [and] lost more than 50 pounds."[38]

The book describing the diet reached number 1 on the New York Times best-seller list—where it spent 40 weeks—and sold more than 12 million copies.[37,38]

The diet hinges on the "secrets of timing and food combining that work with your natural body cycles"—appropriation (noon to 8 PM), assimilation (8 PM-4 AM), and elimination (4 AM to noon).[37] The authors argue that eating foods in the wrong order provokes "rotting" in the stomach"[39] and categorically separates "dead" foods (such as meat and starch, which "clog" digestion) from "living" foods (such as raw fruits and vegetables, which "cleanse" it).[39,40] Dairy products are to be avoided at all times.[39,40]

A day on the diet starts with only fruit and fruit juices. Lunch may consist of "living" foods and dinner of "dead" foods.[39,40]

The Fit for Life diet has been widely criticized for theories that lack scientific grounding or support from clinical trials.[38,39] The diet is also likely to provoke vitamin, mineral, and calcium deficiencies,[39] while potentially causing serious complications in patients with diabetes.


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