Newsletter #204 - Exercise and Genetic Risk of Obesity 🧬
Hey guys! This week, I wanted to take a very brief look at how genes influence obesity risk, and how exercise might affect that association. I am talking specifically about the FTO gene, which holds the strongest known association to risk for obesity. It has been estimated that those who carry two copies of the risk variant of FTO have around a 70% increased risk of becoming obese.
So, why exactly is that? It’s important to bear in mind that FTO does not seem to increase obesity risk through changes in metabolism or fat storage. Rather, research shows that people with certain variants of FTO tend to eat more meals and snacks, consume more total calories per day, and they gravitate toward fats, oils, and sweet stuff.
It is also worth noting that randomized controlled trials show that people who carry FTO risk variants respond equally well to weight loss interventions. In other words, the impact of FTO is modulated by environmental factors - it does not impair one’s ability to lose weight through lifestyle change.
And this makes a lot of sense, if you think about it. The obesity epidemic is a relatively new phenomenon, and can’t really be plausibly explained by changes in our genetic code. Indeed, an analysis of data from multiple generations in the Framingham Heart Study found that FTO was only associated with obesity in people born after 1942, lending further support to the idea that FTO mainly increases susceptibility to weight gain in an obesogenic environment.
So how does exercise specifically affect FTO? And through what molecular mechanisms? Scroll on down to learn more 👀
To learn more, scroll on down 👇🏻
This Week's Research Highlights
🚶🏻♂️ Physical activity modulates the impact of FTO on obesity risk.
Researchers performed a meta-analysis of genetic data from 45 studies of adults in North America and Europe (n = 218166). They divided participants into two categories based on whether they were physically active or inactive. They found that the association of the FTO risk allele with odds of obesity was reduced by 27% in adults who were physically active. Worth noting that this definition of “physically active” was pretty modest, to say the least - anyone who reported more than one hour of exercise per week, or was above the lowest 20% of physical activity for their sex, was classified as physically active.
🏃♀️ Very high levels of physical activity nearly abolish the effect of FTO.
Researchers examined a group of 704 Old Order Amish in Lancaster County in Pennsylvania. This is a useful population for the purposes of this study, because their traditional lifestyles mean that many of them achieve levels of activity that mirror that of our ancestors, and certainly more than the Westerners that were being assessed in the study I just described. The researchers equipped the participants with activity trackers for a week to gauge their physical activity levels, and tested their blood for their FTO genotype. They found that FTO was associated with increased likelihood of being overweight or obese - but only in individuals with lower physical activity scores. When the researchers zeroed in specifically on the most physically active subjects, FTO made no difference in their weight. Author Soren Snitker summarizes the results: “We probably carry genes that 150 years ago were not risk factors for obesity, but because of changes in our environment, they become liabilities.”
💪 High intensity exercise decreases FTO expression in muscle.
A team of scientists in Melbourne recruited 28 untrained subjects and had them exercise on a stationary bike on two separate occasions: once at high intensity (80% of VO2peak), and again at a low intensity (40% of VO2peak). When the researchers took muscle biopsies from the subjects, they found that FTO mRNA expression was significantly decreased after the high intensity exercise. This may be through activation of AMPK, which has previously been shown to lower expression of FTO. So, it is possible that frequency, duration, and intensity of physical activity all affect the extent to which exercise can block the obesogenic effects of FTO.
Random Trivia & Weird News
🐱 Research has confirmed what we already know - cats love to sit inside boxes, even fake ones.
Anyone who owns a cat has probably noticed their affinity for anything cozy and rectangular, like shipping boxes, baskets, suitcases, drawers, etc. But a study published last year found that cats even prefer to sit inside 2-D shapes that resemble squares. Researchers had cat owners put down four circles with 90 degree angles cut into them, creating an optical illusion of a square.
Sure enough, the cats gravitated toward the illusory square, almost as much as the real squares, suggesting that they respond to these kinds of optical illusions much like we do. Why precisely they are so drawn to boxes, and things that look like boxes, is whole o mystery, yet to be determined.
Podcasts We Loved This Week
- Danny Lennon & Alan Flanagan: Artificial sweeteners – Health impacts and “safe” levels. Via Sigma Nutrition Radio.
- Nora Kenworthy & Mark Igra: Why the GoFundMe healthcare plan doesn’t work. Via Science Friday.
Products We Are Enjoying
3-in-1 Plyometric Box
I have been using this box for a couple of months and I highly recommend it to anyone who is interested in doing plyometric exercises.
It’s made of a sturdy foam material, so you don’t have to worry about getting hurt if you miss on a jump, like with those metal boxes they have at gyms. It’s also highly versatile - you can just rotate it if you want to perform a different height.
I have the 16 pound one, but you can also get a 60 pound version if you’re worried about wobbling on the landing.
humanOS Catalog Feature of the Week
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