In reply to bouldery bits:
> Because I like to make all my decisions based on anecdotal evidence, I want to know, what dietary changes worked for you?
> After some surgery a few years back my weight crept up.
> I've now lost all that weight, using the strategy of calories in < calories out over a sustained period and I am back at a weight that works for me and I'd like to maintain. Now though, I want to eat for 'performance.'
> I know this makes me sound like one of them triathlon Wally's, but hear me out.
> Nowadays, I do lots of running for fun, a bit of a cycling, a bit of surfing and some walking in the hills. What should I be eating to maintain my current weight whilst also making my body work really good and stuff?
> There are lots of books and that but largely folk are trying to sell something or have an agenda of some kind.
> So, what has worked for you guys personally?
As a rule of thumb, any diets that encourage not eating for long periods or cutting out entire food groups/large ranges of foods are a bad idea. I'll put this up front - I'm vegetarian and don't drink milk/limit milk products purely on ethical grounds. I'm sure I could improve my dietary quality by consuming both, but my priorities lie differently.
Basically just get it so that calories in = calories out. Save your high sugar foods for before and during performance - so you can have your cake and eat it (literally) so long as its a) before you do some exercise and b) still in your calories in = out. High intensity exercise is fuelled by sugar - so give yourself some! There rest of the time try and keep the sugar down as others have said. Sugar isn't the enemy, sugar AND inactivity are the enemy.
The other thing you'll want to help you perform is enough protein and spread out accordingly. Exercise causes damage you then "super compensate" from (i.e. your body repairs the damage then adds a bit extra) and you need to resources to do this with - protein. My understanding is that you want to get as much as possible, without it using up too much of your caloric budget. If you eat to excess it will a) pass straight through you or b) get used as a pretty inefficient energy source via gluconeogenesis (the liver converts it to sugar). Better to eat a good amount of carbs so that your body isn't do this IMO (as for performance, efficiency is king). To put some numbers on this my understanding is that you want to be shooting for 2g/kg/day for performance (note this is way above the governments recommendations). For someone who is about 75kg, this is 150g. This gets a little more complex in that you need to spread this out through the day (there is an absorption ceiling) in servings of 25-30g. I go for 5 rounds of 30 g myself - 3 meals and 2 snacks. Breakfast, Lunch, Afternoon Snack, Dinner (I eat quite late, 7:30-8ish as I prefer a big meal after training), and pre-bed Snack. For the pre-bed one I almost always just have a protein shake. Can always swap these around if the timings don't work, and there is easily scope for a second breakfast. If you're using a calorie counting app anyway you can keep track of your protein intake easily.
Fat I don't really worry about. I fiddle with the other too and it's just there.
Final thing that makes a difference for me is making sure I get enough iron, sodium and calcium. I'm vegetarian and don't drink milk so basically I supplement for iron and calcium with a decent multivitamin. Some on this thread will argue that the fact I need to do this means my diet is deficient, but I'd argue that the act of supplementation acknowledges I don't get these nutrients from other parts of my diet and I'm fixing it to make my diet non-deficient. Regarding sodium, I cook 99% of my food from scratch so it's pretty low in salt - I make an effort to add sodium and will often have an electrolyte tablet in my water or m are a DIY juice/water/salt mix when I train.
Re resources - the ClimbSci podcast is very interesting and easy to listen too (albeit long) which is run by a couple of chaps who focus on climbing specifically. More generally, I've found the Complete Guide to Sports Nutrition (Anita Bean) pretty good without trying to sell you any weird fad diets.