Caveats to conventional wisdom on fasting & exercise | #11
Caveats to conventional wisdom on fasting & exercise | #11
Greetings everyone—
This month, we have a few studies that remind us to be humble about what science can teach us. The nature of science is that it is constantly evolving, and what is certain today changes we we learn more. They are reminders that there is still room for uncertainty, and there can be exceptions even in practices we regard as generally helpful.
As I wrote in a blog post last year, a lot of research reaches conclusions which are “less satisfying than we’d like, with lots of caveats and uncertainties. Two of the studies below, the first on the effects of rigorous exercise, the second about intermittent fasting, should be taken in that spirit.
Also, I’ve been writing a lot the past few weeks! Check out the new posts:
Ok—now, on to the recommendations!
#1: Intermittent fasting is good for your body…. BUT
In this interesting study, researchers found that limiting meal intake to less than three meals a day can actually be associated with a rise in all-cause mortality compared to eating three squares a day. Skipping meals set at particular intervals usually leads to taking in more energy at once, and this may cause imbalances in the way our bodies regulate glucose, and thus cause deterioration in the metabolic system.
This is only an observational study (not a randomized control trial) where researchers look at the behaviors of groups of people and try to draw conclusions. But it does raise questions about eating in less than a 10-hour window.
Skipping meals, as the study notes, is also more likely among “those who were younger male, non-Hispanic Black, with less of an education and a lower family income. Meal-skipping was also more prevalent among those who smoked more, drank more alcohol, were more food insecure, who ate less nutritious food, had more snacks, and took in less energy overall.”
#2: Exercise is good for you… just don’t overdo it
In this study, male exercisers were followed for changes in coronary artery calcifications over an average six-year period. Those that exercised at the highest intensity level showed increased progression of coronary artery calcifications and plaque.
To be clear, these were men exercising at consistent extreme levels of effort. For most of us, maintaining a good regimen of moderate to occasional high-intensity effort results in 30-40% less cardiovascular disease. A good argument for focusing on Zone 2 training as a significant part of your movement routine.
#3: More points for getting out in nature
Many previous studies have shown that getting out in nature is helpful. What is the dose and how does it impact those in various socioeconomic groups? From this Finnish study, getting out in green spaces 3-4 times a week was associated with a 33% lower odds of using mental health meds, 36% lower odds of using blood pressure meds, and 26% lower odds of using asthma meds across all socioeconomic groups.
#4: HIIT vs. fasting for brain health
According to this study, six minutes of high-intensity cycling raised brain-derived neurotropic factor (BDNF) 4-5 times compared to low-intensity exercise or 20 hours of fasting. BDNF is associated with increases in neuroplasticity (the ability of the brain to form new connections and pathways) and the survival of neurons. This is linked to better brain health and lessens the risk for neurodegenerative conditions like dementia and Parkinsons.
#5: HRT can be preventative for dementia in certain women
Hormone replacement therapy gets criticized and praised depending on the study you read. This one looked at women in England with the APOE4 gene, which is present in 25% of English women. APOE4 confers a higher risk of dementia. The study found that HRT use is associated with better memory and larger brain volumes among at-risk APOE4 gene carriers. The associations were particularly evident when HRT was introduced early—during the transition to menopause, known as perimenopause.