Does water-only fasting help your cholesterol? A new review suggests it might not.

Many people turn to water fasting hoping to reset their health and improve markers like cholesterol. But what does the science actually say about how it affects your blood lipids? A new analysis pooled data from 32 different human studies on water-only fasting to find out. The results were surprising: instead of improving the cholesterol profile, fasting was associated with a significant decrease in HDL (often called 'good' cholesterol) and significant increases in LDL ('bad' cholesterol) and total cholesterol. Triglyceride levels didn't show a clear overall change. It's important to understand what this does—and doesn't—tell us. The people in these studies were compared to themselves before they started fasting, not to a control group who kept eating normally. This means we can only see associations, not prove that fasting caused the changes. The researchers also found signs that studies with certain results might be more likely to get published, which could skew the findings for LDL and total cholesterol. For now, this review paints a nuanced picture: water-only fasting triggers specific shifts in blood fats, but we don't yet know if these are temporary adaptations or what they mean for a person's long-term heart health.