Hi Dr. Kristophine!
So I'm in nursing school and something one of my instructors said about obesity really bothered me and IK you're a doctor who Actually Knows about weight as it pertains to health so I wanted to see if you'd weigh in (pun not intended)
She said, in reference to cancer risk factors,
"poor nutrition, especially one that is high in saturated fats, increases your risk for obesity which increases your risk for cancer... Physical activity, again obesity is a risk factor for multiple disease processes, cancer being one of them... So being immobile increases your risk for obesity which increases your risk for certain cancers."
When I heard that in our lecture vids, to me it seemed like she was using the wrong variables to connect poor diet and lack of exercise to cancer
[disclaimer: this instructor is dangerously incompetent, often wrong in her lectures, no one ever does well on her exams because she doesn't teach properly, and my other instructors for that class are accumulating evidence to get her removed from that position] so I don't take much of what she says as legit, but I'd like to know WHY its illegitimate, if it is
If you don't feel like addressing this all yourself, I'd also appreciate you throwing some resources at me to read
What she’s doing is looking at a set of interconnected variables and assuming a causal relationship. This is dangerous—I would cover why, but I don’t teach psych stats labs anymore—and what she should probably be saying instead is that being sick tends to go with being fat, rather than that being fat causes being sick. To the best of my knowledge, no one has proposed a clear pathway by which being fat would lead to cancer. Now, fat tissue does make estrogen, which raises risk for some cancers—but lowers it for others, and protects bone density, so it’s always a personalized discussion in patients I’m looking at putting on estradiol.
Now, there are definitely dangerous things you can do with diet. Trans fatty acids are more likely to lead to vascular health problems than good old fashioned natural butter. But “diet—>fat—>cancer” is just bullshit, and if any of my beloved haters out there want to produce high-quality and compelling evidence to the contrary, go right ahead.