So there are many scenarios of why you should read this and here are some of them:
1. You don't want to lose weight but you want to "tone up"
2. You think that to lose weight, you are leaning out
There is a common misconception that if you lose weight no matter how tiny you are, you are going to look like a fitness model and have the perfect muscular structure and everything is going to be right in the world. This leads many girls driving themselves into the group to accomplish this by thinking that more and more weight loss is what's going to get them there. I was a prime example of this. When I began "dieting", I was incredibly uneducated so I just thought that meant no calories. That led me to the left side. When I became knowledgeable about how to properly fuel my body and resistance train to sculpt my body, I became the right. Now, this did NOT happen overnight and it's seriously over like 5 years so don't expect overnight changes.
See we all have a base of muscle. When you "diet down" or "lean out", you reveal that muscle, however sometimes when girls get to the leanest that they can be, it's just not good enough so they keep dieting more. It's not normally a dieting down problem but rather a building muscle problem. I'm an extreme example. There are many people that will not end up looking like I do on the right nor do they want to. I get that, and I'm not trying to get everyone to be a bodybuilder but it's important to recognize that sometimes when you diet down, you may still look "skinny fat". The hard truth is that it's going to take a lot of time to build that muscle.
I think that then leads girls to thinking that they need to build muscle first. Many times, girls begin a diet with a bulk. Just no (or at least I don't agree with this). They think they want to build the muscle first and then cut. I think that first you need to cut to see what you are working with (on a reasonable amount of calories) and then if you get to a point where you don't like what you see, then you should slowly add food in and start weight training. My cut and build happened at the same time to be honest. This is called "beginner gains". If you've never lifted weights before and you start, you are going to like what you see most likely.
Here are some reasons that you should lift weights while leaning out or losing weight:
1. It builds your metabolism. Muscle = metabolism end of story. So, this means that you are going to be able to cut at a higher caloric intake
2. It shapes your body ("toning up"). I don't ever say this to people but when they say, they don't want to lose weight but want to "tone up", I know what they really mean is "I want to build muscle on my frame that I have now." and honestly this isn't always the easiest task and can present to be the hardest clients because it's going to take a long time to build muscle.
Women can reasonably gain about 1 pound of muscle every 4-6 weeks. That's if all the stars align correctly with diet and workouts right on track. It's HARD.
If you are at this point, losing more weight and doing more cardio to get there is literally the EXACT opposite of what you want to do. If you think "I'm almost there" and think that you just need to get that final extra layer off, most likely you are just going to end up burning more muscle, lowering your metabolic capacity, and ending up smaller with the same muscular structure so basically looking the same with less shape.
Also, if you say that you want to lean out without losing weight, that's not very possible either. Most of the time, if you really do have a layer of fat over your muscle base, then leaning out is going to just inevitably equal weight loss.
If you begin a diet, and you gain 1-5 pounds in the first week, THIS.IS.NOT.MUSCLE. It simply means that you are not in a caloric deficit and need to adjust your nutrition, NOT quit weight training. If you find that you are "bulking up" while weight training, then you need to fix your nutrition, NOT stop lifting.
This is such a hard topic to discuss and the general population's view on this is very backwards so it's very hard to explain to people because they are already have in their minds what they believe. However, I hope this explains the difference a little more.
With love and weight training,