Bare with me, I'm new to this. I just have several questions for you good people. I'm fascinated by this movement and excited to learn more. Where do you get your calcium from? Whats wrong with fruit? Why are some nuts ok and others aren't? What kind of "on the go" snack would recommend for someone who works a physically demanding job 8 to 9 hours a day? Some posters talk of how great they feel on paleo, while others have long lists of complaints. Why? How is paleo different from a zero carb diet? Should I be worried about ketosis?
See this thread on the best way to get started: http://paleohacks.com/questions/9324/whats-the-best-way-to-get-started-with-the-paleo-diet/9327#9327
Also spend some (OK; a LOT of) time on Mark Sisson's site - very accessible writing providing layman-oriented (but not patronizingly so) answers: www.marksdailyapple.com. His philosophy is not orthodox paleo but it is very close - and his articles lay out the science behind the food choices that paleo-style eaters make.
Here's some short answers to your questions:
Where do you get your calcium from? Calcium is available via the richly nutritious animal products and vegetables you'd eat. Not as crazy-high levels of calcium as when you'd eat a calcium chew or chug milk all day long, but guess what? When you don't eat grains, the grains' antinutrients don't deplete your digested food sources (and ergo what you absorb) of their calcium, so you come out even or even ahead.
Whats wrong with fruit? Nothing inherently wrong with fruit, but to a person whose metabolism has been deranged by the typical American way of eating (high omega-6/omega-3 ratio, insulin resistance stemming from years of blood sugar surges and plunges from grains and sugar, etc.), it can trigger an inordinate insulin response and/or cravings for carbs. Also, lots of fructose has been known to be manifested by the presence of a fatty liver - the same phenomenon caused by excess alcohol. With fruits, moderation, seasonality, and personal sensibility is key. Some people can eat a lot of fruit of all kinds with no metabolic issues, some people stick to lower-carb fruits like berries, tart citrus like grapefruit, etc. Others forego fruit altogether in a bid to help heal their metabolism and lose weight.
Why are some nuts ok and others aren't? Nuts are certainly convenient and a sensible on-the-go option for curbing hunger with a dose of protein and fat. That said, it is easy to go (ahem) nuts on nuts. They are very calorie-dense, so even a few handfuls will add up quickly. Also, most nuts have a high omega-6/omega-3 ratio, which is not desirable since Americans (even paleo Americans, natch) tend to consume excess omega-6 anyway. Finally, we probably consume them in much greater quantities than paleolithic gatherers would have found and been able to crack open. But nuts are not the devil. Some advocate soaking them to rid yourself of some of the antinutrients (phytic acid) present, so if you do indulge, consider that as an option.
What kind of "on the go" snack would recommend for someone who works a physically demanding job 8 to 9 hours a day? Lucky you, Melissa just made a great post today with some sustaining and largely nonperishable meal replacement ideas.
Some posters talk of how great they feel on paleo, while others have long lists of complaints. Why? I'm guessing the discrepancy you're reading here is between those who are past the initial hump of converting to paleo and those who have just started. For those who have just started - well, let's just say that in many instances the transition is uncharitable. Headaches, nausea, etc. can be present as a person's body deals with moving from being fueled by the standard American diet to being fueled by healthy, nourishing fats and protein, abundant produce, etc. The more sudden the change, the harder it will be. Some people go cold turkey, and some gradually change one thing at a time (grains...then sugar...then sometimes fruit or dairy...). For most folks who have been paleo longer than a couple of weeks, though, the testimonials that I've read are generally positive: steady energy, no cloudy thinking or headaches, ability to comfortably go hours without eating, etc.
How is paleo different from a zero carb diet? Should I be worried about ketosis? A small proportion of paleo folks are zero-carbers. One famous zero-carber is Charles Washington, though I'm not 100% certain about whether he's officially self-declared paleo or just paleo-friendly. Most paleo folk aren't zero carb because they do eat at least some veggies (if not also fruits, nuts, etc.) in addition to animal products. Ketosis is not to be feared, unless you want to gain weight, in which case avoid ketosis by the addition of some healthier carbs like tubers, root veggies, etc. and also some fruit. We even go into ketosis while we're sleeping!
Wow! Slow down. Give it 30 days of paleo...
The less crapola sucking anti nutrients you eat (eg grains, for example) the less you need insofar as minerals such as calcium. There is so much info out there, Sisson, Robb Wolf, LaMonde, et al. Read dread read.
Nearly everyone feels better on paleo. The few who complain might be just fine-tuning. Those who really don't feel better on paleo probably don't post here.
Zero carb sounds like paleo for dieters. Paleo is more about quality of food over quantity. Yes, there are good carbs and bad carbs,
Get some sleep. No, get a lot of sleep. Don't stress yourself unnecessarily. Exercise in a way that...oh there's so much here to answer...