Low-carb diets no better than balanced-carbohydrate diets for reducing weight and cardiovascular risk

This systematic review failed to show that low‐carbohydrate weight‐reducing diets are superior to balanced‐carbohydrate weight‐reducing diets, with probably little or no difference in weight reduction and cardiovascular risk factors over the short (3 to 8.5 months) and long term (1 to 2 years).

The small pooled mean differences in weight reduction between the diets (about 1–2kg), while statistically significant in the short term, were not clinically important in the short or long term in overweight and obese adults without or with type 2 diabetes (low to moderate‐certainty evidence). These differences can at least in part be ascribed to biological weight fluctuations.

Most trials included participants without diagnosed cardiovascular disease or events at baseline, and average baseline low-density lipoprotein cholesterol levels and diastolic blood pressure across the trials were within the normal ranges defined for people without coronary artery disease. In people with lipid disorders and variability with atherogenic lipoprotein response, caution in recommending low‐carbohydrate and consequent high‐fat diets is warranted.

Evidence on participant‐reported adverse effects over 2 years was limited, and conclusions about these could not be drawn.