Long-term effects of very low-carbohydrate and high-carbohydrate weight-loss diets on psychological health in obese adults with type 2 diabetes: randomized controlled trial

Background/Objective. Very low-carbohydrate, high-fat (LC) diets are used for type 2 diabetes (T2DM) management, but their effects on psychological health remain largely unknown. This study examined the long-term effects of an LC diet on psychological health. Methods. One hundred and fifteen obese adults [age: 58.5 +/- 7.1 years; body mass index: 34.6 +/- 4.3 kg m +/- 2; HbA1c: 7.3 +/- 1.1%] with T2DM were randomized to consume either an energy-restricted (similar to 6 to 7 MJ), planned isocaloric LC or high-carbohydrate, low-fat (HC) diet, combined with a supervised exercise programme (3 days week +/- 1) for 1 year. Body weight, psychological mood state and well-being [Profile of Mood States (POMS), Beck Depression Inventory (BDI) and Spielberger State Anxiety Inventory (SAI)] and diabetes-specific emotional distress [Problem Areas in Diabetes (PAID) Questionnaire] and quality of life [QoL Diabetes-39 (D-39)] were assessed. Results. Overall weight loss was 9.5 +/- 0.5 kg (mean +/- SE), with no difference between groups (P = 0.91 time 9 diet). Significant improvements occurred in BDI, POMS (total mood disturbance and the six subscales of anger-hostility, confusion-bewilderment, depression-dejection, fatigue-inertia, vigour-activity and tension-anxiety), PAID (total score) and the D-39 dimensions of diabetes control, anxiety and worry, sexual functioning and energy and mobility, P < 0.05 time. SAI and the D39 dimension of social burden remained unchanged (P = 0.08 time). Diet composition had no effect on the responses for the outcomes assessed (P = 0.22 time 9 diet). Conclusion. In obese adults with T2DM, both diets achieved substantial weight loss and comparable improvements in QoL, mood state and affect. These results suggest that either an LC or HC diet within a lifestyle modification programme that includes exercise training improves psychological well-being.