Intermittent Fasting causes Heart Attacks?!
Whats up everyone,
This story made the rounds on social media and went mainstream, and I had to talk about it.
Its one of the best examples of "bad science going popular" Ive ever seen
8-hour time-restricted eating linked to a 91% higher risk of cardiovascular death
This "study" produced a flurry of mainstream media articles all proclaiming that Intermittent Fasting would lead to Heart attacks and was unhealthy.
There were so many things wrong with this "study", I was stumped where to even begin
Lets start at the beginning and break it down
This study was not a traditional study, but an analysis of American data by a Chinese research time at Shanghai University in China. Is that bad? I dont know, Im not anti-Chinese (not that I care about being called racist in the first place), but I did find it peculiar that it was a foreign university analyzing American sourced data to present at the AHA Conference. What made them want to look at this data in the first place?
The study was based on NHANES data. NHANES stands for National Health and Nutrition Examination survey. These are a series of ongoing surveys that are conducted by the CDC (Center for Disease Control). They have been done for over 50 years and they involve using questionnaires to ask people about their health habits across the continental USA.
The NHANES data is extensive, but it is epidemiological data. Its data to draw corellations from, its not causative data, nor is it actually a "study" where anything is being tested for. The data itself is not considered to be particularly robust because the surveys are done as recall surveys. Basically, people are asked questions, and then those answers gets compiled. While this data can be directionally useful, it runs into the issue of people's memories NOT being reliable, especially when it comes to dietary habits. The CDC themselves are aware of this, with the surveyors being trained that "I don't know" what will be a common response.
It is well known in Nutrition science that people are notoriously bad at recalling what they ate, when they ate, and how much they ate. This is has been a known issue for decades. It is bad scientific practice to rely on self reported data for accuracy.
The analysis of NHANES data on diet patterns is particularly egregious. It involved looking at TWO dietary recall interviews over a 15 year time span, with an average of about 8 years apart. Asking people two times in 15 years "when do you eat breakfast lunch and dinner" and expecting accuracy is ridiculous.
The data was based on interviewing men and women, with an average age of 48, and 73% caucasian. Why is this an issue? There is NO mention of BMI, bodycomposition, or exercise habits with the people interviewed. Or the people who died. That would be extremely relevant to contextualize with their eating habits, but its not mentioned at all. (which is ODD, but NHANES does ask people about it) Additionally, this is an OLDER population. This was not 20 something metabolically fit men that were being questioned.
So now we get to the Chinese analysis. They looked at the data and divided people up into eating patterns. -People who ate their meals within an 8 hours or less time frame each day -People who hate 8-10 hour timeframe -People who hate 10-12 hour timeframe People who hate 12-16 hour timeframe The people who ate within 8 hours or less each day were identified as fasting for 16 hours. Again though, this is unreliable data based on two interviews, and the interview questions DID NOT ask anyone if they did "Intermittent Fasting". You can find the interview questions online. There are ZERO mention of fasting or intermittent fasting. -Data DOES exist on Intermittent fasting, and has demonstrated its a chronological strategy that can control calorie intake and improve health.
Thus we now run into the issue of "this was a study on IF" NO IT WAS NOT. To present this analysis as an "Intermittent Fasting study" is pure fabrication and/or willful stupidity. This was survey data on eating habits. This data is devoid of proper context to make informed health assessments, and is an example of why epidemiology so often gets criticized for creating narratives based on associative data (correlation that does not equal causation).
To make all of this more absurd, the only publicly available data on this study was the ABSTRACT. This was a poster presentation from the AHA conference. As in an actual cardboard poster. Not submitted to a journal. Not peer reviewed. Yet if you read articles about it, you would never know that. So we have narratives being spun from an abstract based on analyzing currently non accessible data.
And FINALLY, we get to the conclusion. People who eat their meals within an 8 hours or less time frame were 91% more likely to die of a heart attack. Let accept this as TRUE. The NHANES data does track deaths.
Lets assume the numbers are accurate for these two points. BUT, (and there are a lot of buts)
-Who was actually dying? Overweight men? Overweight women? Did any of these people smoke? What about exercise? What was the average age of the people who died? What were they eating? WE DONT KNOW, BECAUSE NONE OF THIS IS MENTIONED.
As I said during a live broadcast on X, the whole thing is Logically BUSTED.
So what should we learn from this?
1. You can dismiss this study outright. It is not scientifically useful.
2. If Intermittent Fasting is working for you, KEEP DOING IT. The sound evidence that does exists supports it as a health strategy
3. If any research was be done on fasting and cardiovascular mortality, it would need to be long term randomized controlled trials, NOT this bullshit. I know this was lengthy, but per Brandolinis Law "The magnitude of evidence needed to refute bullshit is always many times greater than the bullshit itself"
It's a shame studies like this make it into the mainstream in the first place. There's so much unfortunate noise and confusion in the space. Thanks for writing and contributing to the myth busting of false nutrition claims, Alexander.