Intermittent fasting (IF) is how you eat. It involves following a restricted eating and non-eating (fasting) window. For calorie deficit, boosting metabolism, improving blood sugar management or other health and fitness goals, many people follow intermittent fasting. There are many types of intermittent fasting, depending on the duration of fasting and eating hours.
But if you often do a trust fall on intermittent fasting, then it’s also time to look at the downsides for a reality check. A study published in the journal of Diabetes & Metabolic Syndrome: Clinical Research & Reviews, released on August 22, 2025, raised an alarm over the very short eating periods in intermittent fasting, particularly for heart health.
For context, let’s look at one type of IF. One of the most commonly talked about is the 16/8 method,which features a whopping 16 hours of fasting and eating only within 8 hours. Now this very limited eating window is associated with risks to cardiovascular health.
Heart risks from short eating periods?
The US-based study researchers examined the health records of over 19,000 adults. Based on that, the researchers deduced that those who ate all their meals within an 8-hour window unfortunately faced a 135 per cent higher risk of dying from heart-related issues, like heart attacks or strokes. This was in contrast to those who ate over a 12- to 14-hour period, who were not at such high risk.
As per the researchers, a short eating period may not be good for supporting long-term health. Even if the benefits, like weight or waist-size reduction, are noticeable, the heart may experience problems years later.
The result stated: “During a median follow-up of 8.1 years, compared with eating duration of 12–14 h, eating duration (less than 8) <8 h was robustly associated with higher cardiovascular mortality.”
How may it harm health?
There are many reasons why heart health may suffer from intermittent fasting. Some of the reasons, as the researchers revealed, are that short eating windows over time may result in muscle loss, disrupted circadian rhythm or body clock, and physical stress on the body from hunger pangs. Especially for those who have existing heart conditions, extreme fasting may worsen their health.
So how do you ensure your intermittent fasting is safe? Make sure your eating window is not too short, such as less than eight hours. In addition, nutritionally robust and heart-healthy food should be prioritised during eating periods. In case there are any warning signs like fatigue or dizziness, one should consult a doctor. And anyway, before beginning any diet, medical expert consultation is a must.
Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.
