Will fasting increase your risk of cardiovascular death?

Executive Summary

* A recent presentation at an American Heart Association conference generated global headlines. It claimed that eating within an 8-hour window each day was linked to a 91% higher risk of cardiovascular death.

* The study used data from the US NHANES study for just over 20,000 people. The people had an average age of 48.5 and were followed up for an average of 8 years. During this time 14% of people died, which was strikingly high.

* The people were placed into five very uneven sized groups with five very uneven windows of eating. This resulted in just 2% of people being in the <8 hours eating window group and 59% of people being in the 12-16 hours eating window. The 12-16 hour window was chosen as the reference group despite it not being the highest or lowest group. All of this suggested manipulation.

* The results were presented for all-cause mortality, cardiovascular disease (CVD) mortality and cancer mortality. The results were sub grouped for all people, people with CVD at baseline and people with cancer at baseline. Four eating windows were compared with the reference group. These combinations produced 36 results. Only 4 out of 36 were statistically significant. Most of the research (32/36 associations) found nothing.

* One result (somewhat strangely) found that in people with cancer, there was an association with lower cancer deaths among those eating for more than 16 hours a day. The other three results were all for CVD deaths. They claimed that people in the <8 hour eating window, relative to the 12-16 hour group, had higher risk ratios for CVD deaths.

* The global headlines were based on 0.15% of participants who a) died from CVD and b) claimed that they ate within an 8 hour window. The global headlines were thus based on 31 deaths.

* There were other issues and no plausible explanations but let not the facts get in the way of a good story.