For the past couple years, Intermittent Fasting (IF) has been a major health trend; as a refresher or for those that don’t know, IF is a more regimented way of eating in which one increases the time between eating and decreases the time for eating (for example: someone only eats between 10am-6pm, and then fasts from 6pm-10am).
I currently see clients as a Clinical Health Coach and it is still something that my clients ask me about or assume they should be doing because they have heard the benefits of it. While I am no Registered Dietician, I am very interested in diet behavior and I have personally tried IF in the past. Based on what I have read in the literature and my own account of it – here’s what I’ve learned:
If You Are Biologically Male:
Then your hormones run and adjust on a 24-hour circadian cycle. Studies have shown that having a regimented eating window can lead to an enriched gut microbiome, enhancement of circadian gene expression, and reduced risk of obesity in males. In a nutshell, when you reduce the time window in which you eat, this facilitates a reduction in daily caloric intake, may facilitate a better sleep schedule or quality because you aren’t eating right before sleep, and may speed up metabolism. Many studies showing the benefit of IF have been conducted primarily on males.
If You Are Biologically Female:
Then your hormones run and adjust on a monthly (roughly 28 day / 4-stage) cycle. Because female hormones differ so drastically from male hormone cycles, there is an increasing amount of evidence to suggest that IF may cause hormone imbalances in women who are in their menstruating years. Females require different caloric intake based on the four stages of their hormonal cycle, so reducing caloric intake based on a 24-hour cycle may lead to unwanted fat storage, imbalanced blood sugar levels, and hormones that become out of whack.
Personal Testimony:
I used to be quite strict with stopping any calorie intake by 7pm and not eating anything until 11am. I found that when I stopped eating at least 3 hours before bed, I did go to sleep earlier and I slept better. However, not eating until 11am gave me inconsistent results – sometimes I felt like I had a ton of energy and productivity in the mornings without food, other times I felt sluggish, spacey, light-headed, and lacking motivation. While I still try to stop eating a few hours before bed, I now try to eat within an hour/90 minutes or so of waking up because I have noticed more consistent energy and stability of my blood sugar, which affects performance and mood.
The moral: Hormone cycles are very different for males and females and they react differently to diet behaviors, so get to know more about your hormones and always do your research before trying something new like IF!
Written by GUADS member Kate with contributions from pubmed.ncbi.nlm.nih.gov, pubmed.ncbi.nlm.nih.gov, hopkinsmedicine.org, and Woman Code by Alisa Vitti
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