Shidfar 2010.

Study characteristics
Methods	Randomised, double‐blind clinical trial The trial was conducted in Iran.
Participants	49 overweight men (BMI > 25 kg/m², BMI = 27.5 ± 1.7) Age: 34.4 ± 4.8 years
Interventions	Intervention group: carbonate calcium (1250 mg elemental calcium daily) Control group: placebo Trial duration: 8 weeks
Outcomes	Blood pressure Serum lipid profile
Notes	Diet was assessed with a 24‐hour dietary recall questionnaires at baseline, 4th week, and end of the study.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were divided randomly (by random number tables) into case and placebo groups.
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Double‐blind clinical trial
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not described
Incomplete outcome data (attrition bias) All outcomes	Low risk	4 participants used low‐calorie diets and we had to exclude them from the study (fewer than 10%).
Selective reporting (reporting bias)	Low risk	All outcomes were reported.
Other bias	Low risk	Baseline characteristics were similar between the 2 groups