I rather enjoyed the “Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial” study comparing two very different diets. Both consumed ad libitum, for TWO YEARS.1
“Ad libitum” means the participants were instructed on which foods to eat, but not how much. The results reflect, more or less, how these diets would work in a similar population in the real world.
And one of the stronger points – participants were given cooking classes, recipes, and “written instructions to facilitate preparation of meals at home.” This is one of the things that makes a study like this possible. It’s too expensive to provide all of the food, and teaching these essential skills is possibly one of the most effective ways to helping people make lasting lifestyle changes.
A BRIEF OUTLINE OF THE INTERVENTION
Paleo: meat, fish, eggs, vegetables, fruits, berries, and nuts. Avocados. Rapeseed and olive oils. Exclusions: dairy, cereals, added salt, refined fats, and sugar.
Nordic: emphasis on low fat dairy and high-fibre products. Also, cereals, potatos, vegetables, fruits, and berries (2004 Nordic Dietary Guidelines).
According to Mithril and colleagues,2 the New Nordic Diet is characterized by “a high content of fruits and vegetables (especially berries, cabbages, root vegetables, and legumes), fresh herbs, potatoes, plants and mushrooms from the wild countryside, whole grains, nuts, fish and shellfish, seaweed, free-range livestock (including pigs and poultry) and game.”
Ultimately, the Nordic Diet is relatively similar to the diets recommended by the American Heart and Diabetes Associations – a low fat, high fibre diet.
And importantly, both of these diets excluded processed junk foods and added sugars, so regardless of which group exhibited greater improvements, we can expect that everyone would come out healthier in the end.
Attrition was modestly lower for Paleo dieters (dropouts: 23 vs. 37%), and adherence to the dietary recommendations in terms of macronutrients wasn’t too shabby. See the table below:
Paleo dieters were unable to meet the recommended protein, but got pretty close for fat and carbohydrates. The Nordic dieters were asked to reduce fat and increase carbohydrates, and they did neither. However, given the thorough intervention (ie, cooking classes, recipes, etc.), the foods contributing to these macronutrients likely shifted to the healthier choices outlined above.
Furthermore, the contribution of homemade foods to total food intake likely increased during this study.
The Nordic dieters experienced modest changes in body composition, whereas Paleo dieters experienced significant improvements. The authors weren’t thrilled and said the changes weren’t maintained long-term, however, just looking at the figure below, you may come to a different conclusion:
As mentioned above, the participants were obese – the same type of population who should theoretically benefit more from a diet biased to less carbohydrate and more fat. And by 24 months, that’s where Paleo dieters ended up.
Most metabolic paramaters were modestly improved in both groups, and triacylglycerols were significantly more improved in Paleo vs. Nordic dieters. As this is a known effect of carbohydrate restriction,3 it’s difficult to say if this was due to the food choices, or macronutrients. Lastly, CRP, a marker of inflammation, also exhibited a much greater decline in Paleo vs. Nordic dieters.
In this long-term, outpatient study, those assigned to a Paleolithic-type diet exhibited better improvements in body composition and select metabolic risk factors then those assigned to a Nordic diet.
Dr. William Lagakos received a Ph.D. in Nutritional Biochemistry and Physiology from Rutgers University where his research focused on dietary fat assimilation and integrated energy metabolism. His postdoctoral research at the University of California, San Diego, centered on obesity, inflammation, and insulin resistance. Dr. William Lagakos has authored numerous manuscripts which have been published in peer-reviewed journals, as well as a non-fiction book titled The Poor, Misunderstood Calorie which explores the concept of calories and simultaneously explains how hormones and the neuroendocrine response to foods regulate nutrient partitioning. He is presently a nutritional sciences researcher, consultant, and blogger.
1. Mellberg C, Sandberg S, Ryberg M, Eriksson M, Brage S, Larsson C, . . . Lindahl B. Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial. Eur J Clin Nutr. Mar 2014;68(3):350-357.
2. Mithril C, Dragsted LO, Meyer C, Tetens I, Biltoft-Jensen A, Astrup A. Dietary composition and nutrient content of the New Nordic Diet. Public Health Nutr. May 2013;16(5):777-785.
3. Krauss RM, Blanche PJ, Rawlings RS, Fernstrom HS, Williams PT. Separate effects of reduced carbohydrate intake and weight loss on atherogenic dyslipidemia. Am J Clin Nutr. May 2006;83(5):1025-1031; quiz 1205.