> exercise has also been proven to greatly reduce the risk of depression and Alzheimer's I'm not convinced that it has. Lifestyle interventions in general tend

> exercise has also been proven to greatly reduce the risk of depression and Alzheimer's I'm not convinced that it has. Lifestyle interventions in general tend to be given a lot of hype based on very little hard evidence, probably because lifestyle advice is unregulated and appeals to our biases about cultivating virtue. Of those I'm motivated enough to dig into, claims of lifestyle changes having a large effect on disease tend to be based on at least one of: 1) unfounded assumptions about the significance of a correlation (e.g. since exercise intolerance is a symptom of several cardiovascular and neurological conditions, it may be that getting less exercise is an effect rather than a cause of such a disease) 2) cherry-picking poor-quality or pilot studies 3) exaggerating the practical importance of a well-established but small effect 4) assuming that an intervention proven to improve X in a healthy population must help prevent or treat a disease that involves lowered or impaired X For depression in particular, the effect of physical activity per se virtually vanishes in more rigorous studies, or when comparing leisure to non-leisure physical activity [1] [2]. Basically, the psychosocial meaning of "exercise", and the social structure surrounding it as a positive activity, seems to matter more than the actual exercise. [1] https://www.cochrane.org/CD004366/DEPRESSN_exercise-for-depression https://www.cochrane.org/CD004366/DEPRESSN_exercise-for-depr... [2] https://www.ncbi.nlm.nih.gov/pubmed/21037212/ https://www.ncbi.nlm.nih.gov/pubmed/21037212/