Diet and exercise. . . .
One thing that I find fascinating is that some advisors say "it's all about diet" and other say "it's all about exercise". I was thinking about this, about the way factors interact. (A bit like "nature and nurture", i.e. genes and environment). Usually it's context-dependent.
What brought this on was an article on a weightlifting/bodybuilding site that said "if you're not losing fat as you want to, or if you're not gaining muscle as you want to, it's almost certainly your diet".
Now this is addressed to a community where (presumably) almost everyone exercises. If you're on a site like that, you do some weight training. Most of the people he's addressing are obsessed with exercise. So in that context, that advice is valid. If it's not working, it's probably the diet. But if you address the same question for a group of weight watchers who all control their calories and obsessively eat the right things, then the correct advice is "if you're not getting the results you want, it's probably about exercise".
The two factors interact, and whichever one has more variability in the particular context, is probably the one to work on.
Nature and nurture: people often try to say, "this characteristic (e.g. height, or criminality, or cancer, or whatever) is xx% genes and yy% environmental. But usually, the genes and the environment interact, so it's like having two switches for a landing light: it's not that each one controls the light 50%, or one controls it 40% and the other 60% -- they both control it 100%. Whichever switch you play with, you can turn the light on and off, whatever the setting of the other switch. With genes and environment, it's more often like two dimmer switches, where either can separately produce the full range of brightnesses. So the xx% / yy% thing doesn't mean anything. It's entirely context dependent, just like the diet / exercise thing.
In a setting where the environment is very uniform and there is a lot of genetic diversity, any scientist who does experiments will find that most variation is caused by genes. If there's less genetic diversity and wide environmental diversity, then most variation is caused by environment.
For example, the classic study on intelligence: look at identical twins separated at birth and raised in different families (how those people must get tired of being studied, there are so few of them and they are so useful). See how the correlation between their intelligence compares to that in the population at large, and between twins not separated.
If you do this in a country where everyone gets reasonably well fed, and reasonably well educated, and so on, a lot of the intelligence will be down to genes. If you did it in a country with some very good areas and some areas of dire poverty with starvation, no schooling, no TV etc, and the separate twins sometimes crossed between those, then the percentage due to environment is suddenly going to look higher.
My advice then: if you're not getting the results you want from your diet / exercise regime, it's probably whichever factor you're not really focussed on.
