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The 5:2 diet effectively reduces weight, BMI, and LDL while improving cardiometabolic health in patients with overweight or obesity, per a meta-analysis.

The 5:2 diet, an eating plan characterized by 5 days of unrestricted eating and 2 days of fasting per week, is effective for weight reduction and reducing the risk for cardiovascular disease in patients with overweight and obesity, according to a systematic review and meta-analysis published in the International Journal of Endocrinology.

“Although fasting may cause mild symptoms, none of the articles reported serious adverse effects of the 5:2 diet, suggesting that this diet is safe and feasible,” wrote corresponding author Chunli Piao, MD, and colleagues.

The review and meta-analysis included 20 randomized controlled trials that studied the effects of the 5:2 diet in a total 1393 participants with overweight and obesity in North America, Europe, Asia, and Oceania. Among participants, 689 were in intervention groups and 704 were in control groups.

The 5:2 diet significantly reduced body weight, BMI, waist circumference, body fat percentage, hip circumference, fat mass, low-density lipoprotein (LDL) cholesterol, systolic blood pressure (SBP), and homeostasis model assessment-insulin resistance (HOMA-IR) levels relative to findings in the control group, according to the meta-analysis. Fat-free mass—of which muscle is the main component—also significantly decreased with the 5:2 diet.

“This may be due to muscle loss through mechanisms such as energy deficit, metabolic adaptation, inadequate protein intake, or reduced physical activity,” researchers wrote.

However, the meta-analysis identified no significant changes in levels of visceral fat, total cholesterol, triglycerides, high-density lipoprotein, diastolic blood pressure, insulin, fasting blood glucose, glycated HbA1C, and heart rate associated with the 5:2 diet.

“It is clearly evident that the 5:2 diet caused a significant change in weight and obese appearance of the subjects, as well as lowering LDL and SBP and improving cardiometabolic health,” researchers wrote. “However, except for HOMA-IR, the 5:2 diet did not elicit significant improvements in other glucose metabolism indicators among overweight/obese patients.”

An absence of glucose metabolism abnormalities at baseline, they added, could explain the finding.

Common physical symptoms associated with the 5:2 diet included fatigue, feeling cold, headache, dizziness, and constipation. Common psychologic symptoms were difficulty concentrating, bad temper, and sleep disturbances. Side effects were mild, though, and resolved after fasting.

“However, the patient’s physical condition during the fasting period should be monitored,” researchers advised, “and timely adjustments should be made accordingly.”