Low-carbohydrate diets have been associated with significant reductions in weight and HbA(1c) in obese, diabetic participants who received high-intensity lifestyle modification for 6 or 12 months. This investigation sought to determine whether comparable results to those of short-term, intensive interventions could be achieved over a 24-month study period using a low-intensity intervention that approximates what is feasible in outpatient practice. A total of 144 obese, diabetic participants were randomly assigned to a low-carbohydrate diet (<30 g/day) or to a low fat diet (<or=30% of calories from fat with a deficit of 500 kcal/day). Participants were provided weekly group nutrition education sessions for the first month, and monthly sessions thereafter through the end of 24 months. Weight, HbA(1c), glucose, and lipids were measured at baseline and 6, 12, and 24 months. Of the 144 enrolled participants, 68 returned for the month 24 assessment visit. Weights were retrieved from electronic medical records for an additional 57 participants (total, 125 participants) at month 24. All participants with a baseline measurement and at least one of the three other measurements were included in the mixed-model analyses (n = 138). The low-intensity intervention resulted in modest weight loss in both groups at month 24. At this time, participants in the low-carbohydrate group lost 1.5 kg, compared to 0.2 kg in the low-fat group (P = 0.147). Lipids, glycemic indexes, and dietary intake did not differ between groups at month 24 (or at months 6 or 12) (ClinicalTrials.gov number, NCT00108459).