Carolina Asks: How do weightlifters stay lean while lifting? Do they incorporate cardio if so what type and when?
The first thing to address is that it's a misconception by people coming into weightlifting from other sports (especially CrossFit in my experience) that weightlifters are fat, and there is a fear that if you become a weightlifter, you'll suddenly get fat. You have to step back and consider the facts: There are fat weightlifters, and there are lean ones. There are even fat CrossFitters. I have seen over the last 12 years or so many CrossFitters convert to weightlifting, and the ones who were lean coming into it stayed lean, although you will typically see (eventually) a shift in muscularity, i.e. where the lifter carries more mass.
Typically athletes are either lean or not naturally, and what they do in terms of training and nutrition has significantly less of an influence than their genetics. Almost to a person, the leanest lifters I’ve coached have had the worst nutrition (e.g. pizza and cookies) while those with perfectly dialed-in nutrition ranged from pretty lean to not even close. I realize people hate to hear this, but that truth has been borne out in my experience over and over. There are so many factors that go into it, such as natural testosterone and gH levels, regular quantity and quality of sleep, the amount of stress and the athlete's innate and learned coping mechanisms for that stress, etc.
The other factor that should be addressed, in case you're looking at certain elite lifters when asking this question, is that anabolic drug use can do a great job with leanness and muscularity. Not everyone on drugs is lean, and not everyone lean is on drugs, but you do need to keep that in mind.
Having said that, training and nutrition still can and do influence body composition to at least some degree (how much varies among athletes). In any case, nutrition will have a far greater influence than training. You can create larger calorie deficits and elicit more hormonal shifts through nutrition than you’ll typically be able to through training. Unfortunately, there isn't a formula for that either - some people respond well to reduced carbohydrate, and others are the opposite, leaning out more with higher carbs and reduced fat. You'll have to experiment with that, and also see how each influences your training performance - if low carbs keeps you lean but prevents you from training at the level you need, it's not a good choice. And of course, the other complication is that you need to maintain a specific bodyweight if you're competitive.
Using training (i.e. cardio, crossfit, etc.) in an attempt to lean a lifter out is often counterproductive—it sends contradictory signals to the body for adaptation, and eats up some of the very finite resources each athlete has for recovery. If some kind of conditioning must be done, I find it better to get it by making relatively minor changes the structure of the existing training—perform your warm-ups quickly with no rest, do your accessory exercises (where possible) in circuits with little to no rest, don't sit down during your workouts
, and generally rest less between all sets. This will give some amount of conditioning without fundamentally changing the training or adding inappropriate exercises or work to the program.