Effective strategies are needed to help individuals lose weight and maintain weight loss. The primary aim of this study was to investigate the effect of intermittent energy restriction (IER) compared to continuous energy restriction (CER) on weight loss after 8 weeks and weight loss maintenance after 12 months. Secondary aims were to determine changes in waist and hip measurements and diet quality. In a randomized parallel study, overweight and obese (body mass index [BMI] ≥ 27 kg m−2) women were stratified by age and BMI before randomization. Participants undertook an 8-week intensive period with weight, waist and hip circumference measured every 2 weeks, followed by 44 weeks of independent dieting. A food frequency questionnaire was completed at baseline and 12 months, from which diet quality was determined. Weight loss was not significantly different between the two groups at 8 weeks (−3.2 ± 2.1 kg CER, n = 20, −2.0 ± 1.9 kg IER, n = 25; P = 0.06) or at 12 months (−4.2 ± 5.6 kg CER, n = 17 −2.1 ± 3.8 kg IER, n = 19; P = 0.19). Weight loss between 8 and 52 weeks was –0.7 ± 49 kg CER vs. −1 ± 1.1 kg IER; P = 0.6. Waist and hip circumference decreased significantly with time (P < 0.01), with no difference between groups. There was an increase in the Healthy Eating Index at 12 months in the CER compared with the IER group (CER 8.4 ± 9.1 vs. IER −0.3 ± 8.4, P = 0.006). This study indicates that intermittent dieting was as effective as continuous dieting over 8 weeks and for weight loss maintenance at 12 months. This may be useful for individuals who find CER too difficult to maintain.