BackgroundCardiovascular disease remains the leading cause of morbidity and mortality worldwide, and there is a rising global burden. The effects of diet on cardiometabolic risk factors have been studied extensively. Healthy eating as a cost-effective approach to risk reduction in post-myocardial infarction patients is proven to be beneficial, and the “plate model” is one of the practical methods to achieve this objective.Methods/designThe study will be conducted as a randomized, single-blind, controlled clinical trial for a period of 3 months. A total of 120 overweight (body mass index >23 kg/m2) inpatients (aged 20–70 years) with a history of troponin-positive acute coronary syndrome (ACS) within the 1 month preceding the study will be recruited. Simple randomization will be used in participant allocation. The intervention group will receive the model plate diet. The control group will be provided with routine dietary advice. Other domains, such as advice on exercise and lifestyle modification, will be equalized among patients in both the groups. The visits and evaluations will be done at recruitment (visit 0), 4 weeks, and 12 weeks after the intervention. The primary outcome will be a mean body weight reduction of 10%, and the secondary outcomes will include mean reduction of systolic and diastolic blood pressure, improvement of anthropometric parameters, and improvement of lipid profile and liver enzymes in the test group compared with the control group at 12 weeks following the plate model diet.DiscussionThis study protocol is designed to establish the effects of the plate model diet on modification of cardiometabolic risk factors in patients with ACS. This will also be a pioneering study designed to investigate the practicality of the model plate in local settings and in the South Asian region.Trial registrationSri Lanka Clinical Trials Registry identifier: SLCTR/2016/22. Registered on 22 September 2016 (http://www.slctr.lk/trials/483).Electronic supplementary materialThe online version of this article (doi:10.1186/s13063-017-2057-6) contains supplementary material, which is available to authorized users.