Dietary Carbohydrate and Internal Body Fat

This is a 2-year randomized controlled trial to test the effect of dietary carbohydrates, both quality and quantity, on changes in internal body fat mass. Up to 250 women and men with obesity are recruited in Bergen, Norway, and randomized to one of the following normo- and isocaloric dietary patterns (same amount of protein, polyunsaturated fatty acids and moderate energy, 2,000 - 2,500 kcal per day): 1) a low-fat high-carbohydrate diet primarily with refined (e.g., flour-based) carbohydrate sources, 2) a low-fat high-carbohydrate diet based on minimally refined (e.g., cellular) carbohydrate sources, and 3) a very-high-fat low-carbohydrate diet.

Inclusion Criteria: * Body-mass index (BMI) equal to or above 30 kg/m2 and/or waist circumference equal to or above 102 cm for men and 88 cm for women * Weight stable during the last 2 months before start of the study (less than 5 % change in body weight up or down) * No known diabetes or consumption of diabetes medication * Desire to follow a specified dietary pattern using specific recipes throughout the time of the study period * Ability to periodically record food intake using a specially designed app for the study Exclusion Criteria: * Use of statins and/or diabetes medication * Recent surgical or antibiotics treatment during the last 2 months before start of the study * Chronic inflammatory bowel disease * Serious disease * Smoking * Pregnancy or breast feeding * Alcohol consumption during the study of more than 2 alcohol units per day (1 unit = 15 ml (12.8 g) pure alcohol)