Insulin Resistance Biomarkers Improve on Paleo Diet

Following a Paleolithic diet may help obese, postmenopausal women lose weight and lower their future risk for diabetes and cardiovascular disease, according to a study presented at the Endocrine Society’s annual meeting in Boston earlier this year.

A dietary trend that’s gained increasing popularity in recent years, Paleolithic eating focuses on the types of foods presumed to have been hunted and gathered by early humans. The so-called Paleo diet is comprised primarily of meat, fish, vegetables, and fruit, excluding items that became commonplace after the development of agriculture, such as dairy, grains and grain-based products, and most processed foods.

As the Paleo diet has risen in popularity, it has generated considerable controversy, and very strong opinions on all sides. But there have been few well-controlled clinical studies to test the impact of the Paleo approach in the context of specific medical conditions.

Paleo diet

Caroline Blomquist, a doctoral student in the Department of Public Health and Clinical Medicine at Sweden’s Umea University, and her colleagues randomly assigned 70 obese, postmenopausal women with normal fasting plasma glucose levels to follow either a Paleolithic-type diet or a more typical low-fat diet for 24 months.

Women in the Paleolithic diet group were asked to consume 30% of their total energy (E%, “energy percent,”) in protein, 30 E% in carbohydrates, and 40 E% in fats with a high unsaturated fatty acid content. The Paleo-style diet included lean meat, fish, eggs, vegetables, fruits, nuts, and berries, plus rapeseed, olive oils, and avocado as additional fat sources. Dairy products, cereals, added salt, and refined fats and sugar were omitted.

Subjects in the control diet group were instructed to eat 15 E% of their diet in protein, 30 E% in fat, and 55 E% in carbohydrates. They were encouraged to increase their intake of whole grains, consume low-fat dairy products, and eat three servings of fish per week. For both groups, total caloric intake was unrestricted.

All subjects, regardless of the diet they were following, participated in 12 dietitian-led group sessions and maintained records of their food intake throughout the study.

At baseline, six, and 24 months, researchers documented participants’ circulating lipid levels, gene expression of key factors in fat metabolism and inflammation, insulin resistance, and relative fatty acid composition in plasma. They also collected body measurements and proportions and physical activity data.

After the 2-year intervention, Blomquist found that despite unlimited calorie consumption, both study groups showed similar levels of weight loss and significantly less abdominal obesity. But the women who "went Paleo” showed improved circulating fatty acid profiles, achieved better metabolic markers, and showed increased insulin sensitivity, she reported.

Compared with those on the low-fat diet, the Paleo group showed a marked 19% decrease in “bad” saturated fatty acid intake, while increasing their intake of healthy monounsaturated and polyunsaturated fatty acids by 47% and 71%, respectively. Control group participants, on the other hand, showed no significant changes in fatty acid consumption. Researchers found that specific fatty acids associated with insulin resistance were significantly lower among women who followed the Paleo diet, as compared with the low-fat diet.

They also noted a decrease in delta-9-desaturase activity among Paleo participants. This liver enzyme is associated with liver fat, insulin resistance, and mortality.

Blomquist concluded that “a Paleolithic-type diet, high in polyunsaturated fatty acids, may have long-term beneficial effects on obesity-related disorders, including reduced risk for diabetes and cardiovascular disease.” Polyunsaturated fatty acids have previously been shown to possess antioxidant, anti-inflammatory, and antibacterial properties, offering a host of benefits in the treatment of various chronic conditions, including cardiovascular disease, type 2 diabetes, some cancers, and obesity (Ouyang, X. et al. Int J Mod Biol & Med. 2016; 7(1): 1-11). 

Additionally, by following Paleolithic dietary guidelines, participants essentially eliminated refined and simple carbohydrates -- which are known to contribute to overweight, obesity, and insulin resistance -- from their diets.

“Obesity-related disorders have reached pandemic proportions with significant economic burden on a global scale. It is of vital interest to find effective methods to improve metabolic balance,” Blomquist added. For some patients, a return to a more ancestral way of eating may be the key to better metabolic health.

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