One urban legend states that a diet that has large amounts of protein will somehow leach or suck all the calcium from your bones. This has been proven to be false.
The root of this myth is a study done in the 1980s with fractionated protein powder. Apparently people who took this powder then experienced calcium loss from their bones. Note that these people weren't taking vitamins to supplement their diet.
As just about any nutritionist can tell you, eating powders of food parts is not the same as eating the real, nutritious original food item. Also, having an issue arise when you eat one thing (powder) instead of another (real meat) could be really showing that it was the insufficiency of the artificial food that caused the problem.
So to further explore the issue, long term studies were done with regular meat-eaters who ate meat in a normal way - whether it was burgers, grilled steaks, pork chops or whatever. The studies found that there was no calcium loss, either in the short term or long term.
What the studies showed was that calcium (and other minerals) in your body need to have vitamins A and D in your system in order to be used properly. Protein powder doesn't have those vitamins, while animal fats do. So a person just taking protein powder in essence suffered from a vitamin A and D deficiency because they no longer were getting an adequate supply of those vitamins in their diet. They lost the calcium from their system because of the vitamin deficiency.
A person eating a normal diet of beef, pork and chicken gets vitamin A and D from the fats in those meats, and therefore does not experience the vitamin deficiency syndrome.
Standard natural sources of Vitamin D are animal fats, fish fats, and fish oils. Most adults are at least mildly lactose intolerant, so the Vitamin D artificially added into milk does those adults little good.
Vitamin A is found primarily in eggs, liver, meats, cheese, and milk. It is also found in carrots, spinach and kale.
So there are three lessons to be learned from these studies.
1) Eat natural foods. When you resort to ingesting powders, you miss out on much of the health of the original food.
2) Take vitamins to fill in the cracks. If you do have vitamin deficiencies, you want to fill those in.
3) Eating meats does not cause any calcium issues. If anything, eating meats helps ensure that you get your nutrients in a natural manner, rather than in a pill form.