Newsletter #238 - Exercise, Klotho & Brain Insulin Sensitivity
This week, I decided to take a closer look at a couple of new studies that revealed powerful effects of exercise against physiological aging and in obesity management. Around this time of year (in the Northern hemisphere, that is), the days are shorter and a little colder, and there just seems to be a multitude of tiny barriers to working out. I think many of us (myself included) occasionally need to be reminded of the profound, scientifically validated benefits of physical activity — maybe now more than any other time.
This Week's Research Highlights
🚴 Exercise interventions lead to a consistent rise in levels of the anti-aging protein Klotho.
In Greek mythology, one of the most feared and respected deities was Clotho, who spun the thread of life. She held the power to determine who lived and who died, and thus represented mortality and inescapable destiny. Aptly enough, an enzyme named for her, Klotho, has been shown to be strongly associated with lifespan in both rodents and humans, and administration of Klotho to mice enhances physical and mental performance. Regrettably, only a minority of people naturally generate high levels of Klotho throughout life, so there is immense interest in finding ways to boost it.
To gain insight into how physical activity influences this protein, researchers affiliated with the Catholic University of Brasilia performed a systematic review and meta-analysis of controlled trials that investigated the effects of exercise on levels of Klotho in the blood. After analyzing 12 trials including a total of 621 participants, the researchers found that levels of Klotho increased significantly and consistently after chronic exercise training (for a minimum of 12 weeks).
Interestingly, this appears to be dependent upon the transient increase in free radicals induced by hard exercise. The metabolic challenge of strenuous physical activity leads to an elevation in free radicals, and Klotho seems to be regulated by reactive oxygen species. We tend to think of oxidative stress as a bad thing, but ironically it seems to be critical for a ton of the health benefits of exercise (check out this podcast for more info on how that works).
🩸 Exercise restores brain insulin sensitivity in people with obesity, leading to metabolic and cognitive improvements.
Insulin resistance and obesity are closely linked. Typically, when we talk about insulin resistance, we are referring to cells in the muscles, fat, and liver. However, recent evidence shows that the brain is an insulin sensitive organ, and insulin signaling has been shown to play a particularly important role in weight maintenance in animal models. To see whether physical activity could reverse brain insulin resistance in humans, researchers at the University of Tübingen in Munich recruited 21 participants with obesity and put them through an 8-week supervised aerobic exercise program (3 sessions per week, one hour per session). Before and after the intervention, researchers used functional MRI and administered insulin intranasally to assess brain insulin sensitivity.
Sure enough, the exercise program resulted in enhanced insulin action in the brain — all the way up to the typical level of a person with a healthy body weight. This improvement in brain insulin sensitivity, in turn, elicited benefits throughout the whole body, including increased mitochondrial respiration in skeletal muscle, reduced visceral fat, reduced hunger, and better performance in tests of cognition. Lead author Stephanie Kullmann summarized:
The exercise intervention increased the insulin-stimulated activity in brain regions that are responsible, among other things, for the perception of hunger and satiety and for the interaction of motivation, reward, emotion and exercise behavior.
- Improved mitochondrial respiration in skeletal muscle,
- Reduced visceral fat,
- Reduced hunger,
- and better performance in tests of cognition.
Random Trivia & Weird News
In 1939, the US celebrated Thanksgiving on two different days — for the sake of the economy.
Thanksgiving has traditionally fallen on the last Thursday of November because that was the day that Abraham Lincoln observed it when it was initially declared a national holiday back in 1863. However, in 1939, this meant that Thanksgiving was scheduled for the last day of November, just 24 days before Christmas. Some retailers expressed concern that they would lose business because it would compress the holiday shopping season. Roosevelt yielded to this pressure and moved Thanksgiving to November 23rd.
As you might expect, this resulted in widespread resistance, with some states outright defying the proclamation. As a result, Thanksgiving was celebrated on different days depending on location. The public outcry eventually led to Congress passing a law ensuring that Thanksgiving would always be celebrated on the fourth Thursday of November.
Podcasts We Loved This Week
- Emma Boyland: How Food Marketing Impacts Eating Behavior. Via Sigma Nutrition Radio.
- Karl & Spencer Nadolsky: Pearls from Obesity Week. Via Docs Who Lift Podcast.
Products We Are Enjoying
Whole Foods Market Limited Edition Frozen Riced Cauliflower Stuffing
I'm normally wary of meals that incorporate cauliflower as a substitute for rice or other starches, but this is really good. It has become one of my favorite seasonal products. Unfortunately, it’s not around for very long, so you’d better run and grab it soon. Also, I’d recommend following the stovetop instructions closely when you make it, to ensure that it doesn’t turn out too watery.
humanOS Catalog Feature of the Week
Thanks for reading, enjoy the weekend, and we will see y'all next week!