Answer: Ha! You thought the answer would be simple? Just like many of the latest wellness trends, the web of information on the internet can make questions like this tough to untangle.
Fasting and intermittent fasting is nothing new. According to Encyclopedia Britannica, medical fasting dates at least as far back as the Greek physician Hippocrates, 5th century BCE (the same physician behind the famous oath all doctors take: Do no harm). Organized research behind the physiological effects of fasting occurred in the late 19th century. Since then, fasting methods have become more and more sophisticated as our understanding of the body processes around food consumption and absorption has evolved.
Intermittent fasting is a type of fasting that has grown in popularity due, in part, to the relative ease of doing it daily. By shrinking the time you consume food to, most commonly, an 8 hours window, you allow your body to enter a fasting state for the time in between. This has consistently shown reduction in insulin resistance, which is directly correlated with improved weight management and the reversal of diabetes and other metabolic dysfunction. Most people will choose to fast around 16 hours overnight, finishing dinner at 6 or 7, then breaking their fast at 10 or 11 a.m. the next day. Although this strategy will get results when done effectively and consistently, new research suggests it may not be an optimal strategy.
A new study presented in March 2021 at The Endocrine Society’s annual meeting examined fasting blood sugar levels and survey data for over 10,000 participants. They were specifically looking to see how fasting blood sugar levels and estimated insulin resistance were affected by different eating/fasting windows. As expected, those that fasted the longest did have lowest insulin resistance or best outcome. But people that ate their first meal before 8:30 a.m. also showed lower insulin resistance, regardless of whether they restricted eating to less than 10 hours or spread their meals out over greater than 13 hours.
These findings suggest that eating early in the morning (before 8:30 a.m.) may be another important habit linked with improving metabolism. This most recent research joins others investigating our fluctuating and differing hormone production associated with wake/sleep cycles and their impact on our metabolism. So, while the practice of intermittent fasting continues to show improved effects on metabolism, adjusting your fasting window to finish dinner between 4 and 5 p.m. might produce even more powerful results.
So what’s better?
Answer: An early dinner.