Adherence to low-carbohydrate and low-fat diets in relation to weight loss and cardiovascular risk factors

Objective: A low-carbohydrate diet can reduce body weight and some cardiovascular disease risk factors more than a low-fat diet, but differential adherence may play a role in these effects. Methods: Data were used from 148 adults who participated in a 12-month clinical trial examining the effect of a low-carbohydrate diet (<40 g d⁻¹) and a low-fat diet (<30% fat and <7% saturated fat) on weight and cardiovascular disease risk factors. We compared attendance at counselling sessions, deviation from nutrient goals, urinary ketone presence and composite scores representing the overall adherence based on the distribution of these individual indicators between two interventions. Results: Composite scores were similar between the two groups. A one-interquartile-range increase in composite score representing better adherence to a low-carbohydrate diet was associated with 2.2 kg or 2.3% greater weight loss, 1.1 greater reduction in percent fat mass and 1.3 greater increase in proportion of lean mass. Indicators of adherence to a low-fat diet were not associated with changes in weight, fat mass or lean mass. Conclusions: Despite comparable adherence between groups, a low-carbohydrate diet was associated with greater reductions in body weight and improvement in body composition, while a low-fat diet was not associated with weight loss.