IF Chat – How does IF affect gut health?
When we restrict feeding, that obviously means eliciting control over when nutrients are hitting our GI tracts. The more restrictive we get, the longer the gut and the bacteria that live there go without new material to work on. The “gut microbiome” is all the rage in health research and trends right now, so if you haven’t heard about it, here’s a primer. (Mayo Clinic, lengthy)
Today I’m going to focus on one literature research overview, which is comprehensive and talks about circadian rhythm and sleep as well as the gut microbiome. It’s truly an interesting analysis and if you have time you should read their whole article.
Authors Patterson and Sears over at the Annual Review of Nutrition performed a literature review for the “Metabolic Effect of Intermittent Fasting”. Their very in-dept review is long, but here are some highlights:
- Pubmed was utilized for the review, performed in October 2016
- Search terms included “intermittent fasting”, “fasting”, “time restricted feeding”, and “food timing”
- Over 200,000 papers were found with those search terms
- Inclusion criteria for this literature review were:
- randomized controlled trials and non-randomized controlled trials
- adult male and/or female participants
- end points that included changes in body weight or biomarkers of the risk of diabetes, heart disease, or cancer
- Only 16 papers met the criteria and were reviewed for this work
- Most of these studies enrolled less than 50 participants
- Most trials were only for a short period of time
While discussing “health promoting mechanisms associated with fasting”, and the gut microbiome, the authors state the following (which I’ve broken down in more laymans terms after each section):
“Many functions of the (GI) tract exhibit robust circadian, or sleep–wake, rhythms. For example, gastric emptying and blood flow are greater during the daytime than at night and metabolic responses to a glucose load are slower in the evening than in the morning (87).” ie: Our guts work in various cycles thru the day; for instance, metabolism is generally faster during the day and we respond less quickly to carb-heavy meals in evening.
“Therefore, it is plausible that a chronically disturbed circadian profile may affect (GI) function and impair metabolism and health (27). The gut microbiome impacts metabolic health; its diversity is regulated by diet; and it has a circadian rhythm that is entrained by food signals (83, 102, 105, 119).” ie: The composition of the bacteria in our guts is affected by what and when we eat, and IF interrupts the normal rhythm of our guts, and thus must affect the composition of our gut bacteria.
“(IF) may directly influence the gut microbiota, which is the complex, diverse, and vast microbial community that resides in the (GI) tract. Studies suggest that changes in the composition and metabolic function of the gut microbiota in obese individuals may enable an obese microbiota to harvest more energy from the diet than a lean microbiota and, thereby, influence net energy absorption, expenditure, and storage (83, 102, 105).” ie: The microbiome found in obese people tends to absorb more calories than the mircobiome of healthy weight people.
“Diet-induced obesity dampens cyclical microbiota fluctuations. Time-restricted feeding in mice partially restores these cyclical fluctuations (123). Thus, cyclical changes in the gut microbiome resulting from diurnal feeding and fasting rhythms contribute to the diversity of gut microflora and represent a mechanism by which the gut microbiome affects host metabolism.” ie: When people are obese because of their diets (which is the reality of most obesity cases), the rhythm of their guts is ‘off’. It has been seen that IF may restore the appropriate rhythm and the health of the microbiome.
“An extended fasting period could also lead to reduced gut permeability and, as a result, to blunted postprandial endotoxemia (50, 61, 64, 73) and to blunted systemic inflammation (94, 102), which are typically elevated in obesity. Investigators from the Salk Institute for Biological Studies reported that a brain–gut pathway activated in the brain during fasting acts to promote energy balance by enhancing gut epithelial integrity (95).” ie: Giving the gut time to rest (fasting) may allow more time for the lining of the GI tract to heal or attend to any ‘leaky’ areas. A more intact gut lining gives a fuller and more flourishing microbiome.
Take away from this particular literature review: IF allows the GI tract time to rest and actually perpetuates a healthy landscape for gut bacteria.
The end of 12:12…. How did week 3 go?
The third and final week of 12:12 fasting went well. There was one failure related to not holding to the fasting window (Friday, when drinks with a date went til 12am).
After throwing in the towel on Dry January, drinking was the biggest challenge this week. On Monday, MLK day, I was in the middle of “KonMari-ing” my wardrobe when a friend called for company after a breakup. So I joined a couple friends and provided moral support to our loved one in need, over drinks. One friend came over after to order Thai food and watch a movie, so Monday did not go at all as planned. Tuesday to Thursday were fine with no drinking, most meals from home except for Wednesday dinner (date at Martin’s in Georgetown).
Friday there was a power outage on my block so I was unable to eat before going to the gym (no microwave, no stove, no opening the fridge, you get it). I did grab my smoothie from the fridge and drank it while walking to Sweetgreen for an emergency lunch out. Sweetgreen is a good choice to fall back on, plus I had a giftcard!
Friday evening I met a date for drinks between 9pm-12am. Saturday evening I had another date (when it rains, it pours?) and four glasses of wine, but we ended pretty early for a weekend night. Sunday also did not go as planned because a couple day-drinks (< poor choice on my part) led me to open a bottle of wine at home, have two glasses while watching “RENT” on Fox, and I got basically nothing done that I had wanted to that day.
- Not drinking on weekdays (3 wins, 2 fails counting Sunday)
- No calories in after 9pm on weekdays, 10pm on weekends (one fail)
- Didn’t let power outage on Friday lead to excuses not to exercise or choose a cheat meal over something healthy
- Spreading out smaller meals = never hangry
- Switched to 14:10 on Sunday
Week 4: January 28 to February 3rd
- 14hr fasting : 10hr eating is planned to look like this:
- Meal planning / prep: pretty easy since I’m relying on easy to prep things and soups from my freezer…
- To eat this week:
- Tuesday I need to use up some chicken, tortilla chips, cheese, salsa, and jalapenos… hence nachos for lunch
- Smoothies (still spinach, 1/2 banana, pineapple, soy milk, whey)
- I use Muscle Feast Isolated Whey in Vanilla
- Hashbrowns (potatoes, bell pepper, onion)
- with 2 eggs and 1/2 avocado
- Salads with tomatoes, carrots, dressing (balsamic or Goddess)
- Soups defrosted from freezer
- Left two evenings open for dates but have plenty at home in case
- Monday evening plans involve late pizza and wine so I included this in my planning, complete with shifting the eating window to accommodate
- Left Saturday open and Sunday I’ll end up watching the Superbowl somewhere and plan to make soft pretzels (recipe + pics next week)
- Realistic goal-setting related to drinking:
- Mon – 2 glasses wine
- Tue – Fri no drinking
- Saturday – 2 glasses wine
- Sunday – 5 drinks during super bowl (1 per quarter + halftime)
Not a lot on the grocery list this week since most of this is already on hand. I need to pick up a couple smoothie ingredients and gruyere for the french onion soup.
One goal this year was to write about something not related to my diet experiments at least once a month. So… Thursday, I’ll be publishing a blog post on the history of the Michelin guide! Stay tuned 🙂