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Study under review: A heterogeneous response of liver and skeletal muscle fat to the combination of a Paleolithic diet and exercise in obese individuals with type 2 diabetes: a randomised controlled trial.
Introduction
Type 2 diabetes is a metabolic disorder characterized by a resistance to insulin, leading to a reduced ability of muscle and fat cells to properly uptake glucose and consequently resulting in chronically high levels of blood glucose. The prevalence of both type 1 and type 2 diabetes is estimated to be 12%-14%[1] of the U.S. population. Globally, recent estimates indicate a prevalence of 8.8% in 2015 that is expected to grow[2] to 10.4% by 2040, with 90% of all cases[3] estimated to be type 2 diabetes.
Obesity[4], particularly abdominal obesity[5], is very strongly associated with type 2 diabetes. Type 2 diabetes has also been shown to be correlated with non-alcoholic fatty liver disease[6], visceral fat, inflammatory cytokines[7] like interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFα), and an elevated intramyocellular lipid (IMCL) content[8] (i.e. fat in the skeletal muscle).
Diet and lifestyle interventions have been shown to be very effective[9] at sustainably reducing the incidence of type 2 diabetes. These interventions, which require significant diet and lifestyle modifications, can even be more effective[10] than first line diabetes drugs like metformin at reducing the risk of developing type 2 diabetes. A recent meta-analysis[11] concluded that interventions with diet modification and exercise that included both aerobic and resistance training were the most effective at reducing biomarkers of type 2 diabetes. However, limited evidence suggests that interventions that include both exercise and diet perform as well as[12] exercise alone.
Public interest in Paleolithic-style diets has increased dramatically over the past several years. Just like the "Mediterranean diet," the "Paleo diet" is not a detailed dietary prescription, but rather a set of rules that requires one to consume a diet consisting largely of meats, vegetables, fruits, nuts, and tubers, while excluding cereal grains, dairy, and products with added salt and sugar.
In people with type 2 diabetes, the Paleo diet has performed favorably against diets based on national dietary guidelines[13], the Nordic Nutrition Recommendations[14], and a standard low-fat diet[15] in clinical trials. The study under review would be the first to examine the differences between a Paleo diet alone and a Paleo diet with a combination of aerobic and resistance exercise.
Type 2 diabetes is a growing problem in the U.S. and globally. Treating type 2 diabetes with diet and exercise has been shown to be very effective, but few studies have focused on treatments with a Paleolithic-style diet and none have examined the effect of adding exercise to this diet and the differential effects on liver fat and intramuscular fat stores.
Who and what was studied?
What were the findings?
What does the study really tell us?
The big picture
Frequently asked questions
What should I know?
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