In November of 2014, the International Journal of Obesity published a study conducted by Swedish researchers comparing Paleo-inspired diets with those based on the Nordic Nutrition Recommendations (NNR).1 The NNR are comparable to the USDA’s dietary guidelines, emphasizing low-fat dairy and cereal grains and recommending a macronutrient distribution of 55-60% of calories from carbohydrates, 25-30% from fat, and 15% from protein. The macronutrient distribution used in this study to represent the Paleo Diet was 30% carbohydrates, 40% fat, and 30% protein.
The researchers grouped 49 overweight or obese postmenopausal women into the Paleo and NNR groups, tracking their progress over two years. They were primarily serving how these diets influence glucocorticoid metabolism. Glucocorticoids are stress hormones that modulate various metabolic, inflammatory, and cardiovascular processes.2 Abnormal glucocorticoid metabolism is associated with metabolic syndrome and obesity.
Cortisol, the principal active glucocorticoid, is secreted by the adrenal glands and converted to cortisone, the inert form.3 One of the enzymes responsible for this conversion is called 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). Obese individuals demonstrate increased activity of 11β-HSD1 in subcutaneous adipose tissue (SAT), which is fatty tissue directly under the skin. The researchers hypothesized that diet-induced weight loss results in decreased expression of 11β-HSD1 in SAT and thus a reversal of the abnormal glucocorticoid metabolism common to obese patients.
The study’s participants were observed at baseline, after 6 months, and after 24 months. Both groups lost weight and decreased BMI, waistline measurements, and total body fat throughout the study. The Paleo group had greater reductions after 6 months, but after 24 months there were no significant differences between the groups. Both groups also demonstrated decreased activity of 11β-HSD1 in SAT. The researchers noted, “We did not find any major difference between diets on glucocorticoid metabolism.”4
