Will fasting increase your risk of cardiovascular death?

March 25, 2024 news

The American Heart Association recently held the Epidemiology and Prevention / Lifestyle and Cardiometabolic Health Scientific Sessions from March 18th to 21st, 2024, both in Chicago and online. One of the "highlights" from this event was a press release titled "8-hour time-restricted eating linked to a 91% higher risk of cardiovascular death," which gained widespread media attention. The release was based on a study presented as a poster by Chen et al., exploring the association of 8-hour time-restricted eating (TRE) with mortality rates, particularly cardiovascular deaths.

The study aimed to investigate whether adhering to an 8-hour eating window daily was associated with long-term health benefits, focusing on mortality outcomes rather than just markers of health. Referencing data from the US National Health and Nutrition Examination Survey (NHANES) spanning from 2003 to 2018, the researchers assessed dietary patterns of participants over two separate occasions. However, several methodological issues cast doubt on the validity of the findings.

First, the reliance on participants' recall of food consumption from a single day, twenty years prior, introduces considerable recall bias and inaccuracies inherent in food frequency questionnaires. The uneven allocation of participants across eating window groups, along with with an unusual choice of reference group (12-16 hours) also raises concerns about potential bias and manipulation of results.

The characteristics table revealed stark demographic and health differences between participants in different eating window groups. While the study reported a strikingly high death rate of 14%, it lacked adjustment for important confounding factors such as diabetes, hypertension, and shift work, among others.

Looking closer at the poster's results, it's clear that the headline-grabbing claim of a 91% higher risk of cardiovascular death associated with 8-hour TRE was based on a tiny subset of participants (0.15%) who both died during the study period and reported eating within an 8-hour window. Further, the lack of statistically significant findings in most comparisons highlights the weakness of the claims being made.

The poster concluded by saying "These findings require replication but do not support long-term use of 8-hour TRE for prevention of cardiovascular death nor for improving longevity", which is nonsense. Nothing was found for all-cause mortality, so longevity can't be mentioned.