I asked Grok about some confounding factors in claims made for vegetarian-style eating. One obvious confounding variable is that vegetarians tend to be young females who may have several health advantages to start with.
Here is Grok’s answer:
You’re raising an interesting point about confounding factors in health studies related to vegetarianism, and it’s a valid lens to examine the data through. Let’s break this down.
Research consistently shows that vegetarians tend to have better health outcomes—like lower risks of heart disease, type 2 diabetes, and certain cancers—compared to omnivores. For example, a 2019 study in The BMJ found vegetarians had a 22% lower risk of heart disease, and a 2021 meta-analysis in Critical Reviews in Food Science and Nutrition linked vegetarian diets to lower blood pressure and cholesterol. But you’re right to question whether these outcomes are purely due to avoiding meat or if other variables—like age, sex, and socioeconomic status—are muddying the waters.
The demographic skew you’ve noticed is real. Surveys, like the 2022 Gallup poll, show that in the U.S., 6% of women versus 4% of men identify as vegetarian, with younger women (especially under 35) being the most likely group. A 2023 YouGov survey in the UK found 8% of women versus 5% of men were vegetarian, with the gap widest among 18- to 24-year-olds. This trend holds in other wealthy nations too—Australia’s 2021 Roy Morgan data pegged women at 13.7% vegetarian versus 9.6% for men. Why? Social factors (empathy, environmental concerns), marketing (plant-based diets often target women), and cultural norms around meat and masculinity might play a role.
Now, tie this to health studies. Young women, particularly in economically strong countries, are often healthier at baseline. They’re less likely to be overweight—CDC data from 2023 shows U.S. women aged 20-39 have a 34.7% obesity rate versus 41.6% for men—and they tend to smoke less and exercise more (per NIH stats). Economic advantage compounds this: higher-income individuals have better access to healthcare, fresh produce, and gym memberships. A 2020 American Journal of Clinical Nutrition study noted vegetarians were more likely to be female, younger, and have higher education and income—traits already linked to better health.
So, is vegetarianism just a marker for these advantages? Possibly. Studies often try to adjust for confounders like age, sex, and income, but it’s tricky. A 2018 Nutrients paper found that after controlling for lifestyle factors (exercise, smoking, BMI), vegetarians still had lower mortality rates—but the gap shrank. Another 2022 study in PLOS Medicine suggested that while plant-based diets help, the healthiest vegetarians were those who also avoided processed foods and stayed active—habits more common among young, affluent women.
Your hunch aligns with this: the “vegetarian health edge” might partly reflect a population that’s already primed for good outcomes. Teasing out diet’s standalone effect requires razor-sharp study design—randomized trials, not just observational data. Until then, the headlines touting vegetarianism’s benefits might be overselling it, while underselling the role of being young, female, and well-off.
Eating more “whole foods” and less processed foods appears to confer benefits. The processing of foods – canning, freezing, cooking/prep’ing for “pre-packaged” foods ends up removing many, if not most nutrients such as vitamins. White flour is pretty devoid of nutrients, for example, compared to whole wheat grains. We are better off eating real food – steamed vegetables, legumes, whole grains – than heavily processed versions of those foods. You will likely see health benefits from eating real food …
