For two years, 70 obese postmenopausal women with normal fasting plasma glucose levels ate either a Paleolithic-type diet or a “prudent” diet. The Paleolithic-type diet was based on lean meat, fish, eggs, vegetables, fruits, nuts and berries, with rapeseed, olive oils and avocado as additional fat sources. The diet excluded dairy products, cereals, added salt and refined fats and sugar. 30% of the calories were supposed to come from protein, 30% from carbohydrates, and 40% from fats with high unsaturated fatty acid content. The prudent control diet had a markedly different target: 15% in protein, 30% in fat, and 55% in carbohydrates.
Both groups took part in 12 group sessions led by a dietitian, and kept ongoing records of their food intake.
Both groups lost significant body weight and had significantly less abdominal obesity, but the women eating the Paleolithic-type diet also had significantly lower levels of specific fatty acids associated with insulin resistance, compared with those on the prudent control diet. Presumably this reflects the marked change in the types of fats eaten. At the end of the two years, the women eating the Paleolithic-type diet reported that their intake of saturated fatty acids decreased by 19%, while monounsaturated fatty acids increased by 47% and polyunsaturated fatty acids by 71%.