In the home stretch for IF and it has been a fun experience. 16:8 proves to be the best for my lifestyle, but being lenient on the weekends when social life calls is also necessary. Also interested to see how my lifting progresses as I add breakfast back in (read under “challenges”, below).
“Impact of intermittent fasting (5:2) on ketone body production in healthy female subjects” – Ernaehrungs Umschau international, January 2019.
Our last IF Chat will focus on a small study found via Google Scholar when limiting the research year to 2019. The researchers look at ketone production in healthy females performing 5:2 IF (which was a variation I had thought about trying when “alternate day fasting” didn’t work out for me. See Intermittent Fasting – Week 11).
This article caught my interest mainly because the subjects were healthy females, not the overweight/obese population.
Review of the article:
- The researchers postulate that the positive changes in metabolism seen with IF are due to the body going into ketosis (ie: using fat for energy instead of glucose/sugar)
- Beta-hydroxybuterate is one of the main ketone bodies created by fat metabolism. The researchers also postulate that there is evidence stacking up to suggest that Beta-hydroxybuterate performs cell signaling to impact gene expression, fat metabolism, neuronal function, and metabolic rate. Thus, Beta-hydroxybuterate may have implications for the prevention/treatment of diseases such as Alzheimers and diabetes
- The researchers chose to look at Beta-hydroxybuterate levels in the blood of subjects undergoing a 5:2 IF diet
- Study subjects:
- 19 women, aged 18-30, BMI 18-25 (healthy)
- No medications or excessive use of nicotine / alcohol
- No history of diseases or disordered eating
- Not pregnant or breastfeeding
- No on special diets (vegan, vegetarian, keto, etc)
- This study took place over seven days for 5:2 IF
- The subjects were sent home with instructions on how to perform 5:2, as well as with devices for collecting their own blood samples for glucose and Beta-hydroxybuterate evaluation
- Subjects collected blood to test for glucose and Beta-hydroxybuterate in the morning and the evening of the two fasting days, as well as the mornings after the fasting days
- Out of 19 women enrolled, 13 finished the study
- Drop out rate of 32%
- One cited issues with personal schedule while others dropped out due to “feeling unwell” during fasting days
- Fasting day 1:
- Beta-hydroxybuterate concentrations increased through the day, and were highest the next morning, suggesting that the overnight portion of the fast elicited the most fat metabolism
- Fasting blood glucose decreased through the day and was lowest the next morning
- Fasting day 2:
- Both of the above findings were repeated, but the differences were much less extreme
- The women lost approximately 2lb during the week
- Out of 19 women enrolled, 13 finished the study
- The “ill-feelings” which nearly half the women reported on the morning after the first fasting day were likely due to low blood sugar. Since the blood sugar did not drop as low after the second fasting day, the symptoms were less severe.
- The researchers were perplexed by the results on the morning after fasting day 2, as they were expecting Beta-hydroxybuterate levels to be as high, and the glucose levels to be as low, as after the first fasting day. Thus, they state that “further studies on intermittent fasting and ketone body production are required.”
- The researchers also note that some of the dropout rate could be due to the research period being in December, when it’s cold and close to Christmas, and that there was no financial incentive
- To close, the researchers conclude that data recording hormones (glucagon, insulin), free fatty acids, and the filling of glucagon stores would also be of interest in the IF population
I found this study entertaining and would certainly love to see more research about IF and it’s effects on healthy weight people. Obviously a longer research period, a larger study population, a control group, and more parameters to be evaluated would make this sort of research more impactful.
Week 11 in review:
Weekdays were good, again, because of planning. Even though I Taking a few hours on Saturday/Sunday to get yourself organized for the week ahead really works! I always use my meal prep time on Sunday evenings to listen to pod casts and call friends/family, as well!
Sticking to strict 16:8 IF on Friday and Saturday was challenging because of social stuff. Friday evening I got called last minute to go to a comedy show so I had dinner once I got home, around 10:30pm. Saturday I began eating around 3pm and was out with friends after out gym party till about midnight. That’s only an hour difference.
This week we began to reach for new PRs (personal records) at the gym, and the only one I was able to achieve was my back squat. I hit my old one rep maxes for snatch (75#), push press (110#), and power clean (120#) between Monday and Wednesday, PR’d my back squat at 190# on Thursday, then missed my 1RM for deadlift on Friday with my heaviest lift at 250# (1RM is 260#, goal is 280#). I’m not sure if this is because I’m doing a good amount of cardio / spin classes, because I’m focusing on getting better at skills (pull-ups, hand stand pushups, double unders, etc), because of skipping breakfast, or if it’s a combination of things. As we move into quarter 2 at the gym, I’ll be doing Whole 30 and the Tim Ferriss “Slow Carb” diet, so I will be adding a protein-filled breakfast back in around 8-9am. I also plan on amping up my attention to each lift, practicing form, and spending a little more time being patient with the numbers instead of just trying to rip them off the floor.
Last week on “strict” 16:8 IF! I don’t foresee any issues during the week, and have nothing planned so far for the weekend. Previously, I stated that I would like to get through some of the grain in my pantry, so I do a bit of that this week… Hungry Harvest brought mushrooms, white asparagus, kale, onions, tomatoes, and avocado so here is the menu for this week: