Depending on who you talk to and what their qualifications are, you will get different answers to this question: should I do cardio or weights in order to lose weight?
The answer: both, but emphasize weights in each workout! Now, this may seem like something that doesn't seem to be the best or that you may think you don't want to do because you don't want to get bulky, but I want to take the time today and go over why this is the best option!
Most "fitness influencers" will tell you that you need to go and do some type of cardio on either a machine or some high intensity cardio (HIIT training) but did you know that your body stops burning calories from that workout right after you are done? Once you complete all the movements or you do your 30 minutes on the treadmill your body just stops burning those extra calories. Now, your metabolism still works through the day to burn along with the steps that you take help as well, but this does not provide the best option in order to lose weight.
So, as mentioned above, the cardio that you do provides benefit while you are doing it, but then your metabolism has to take over. As you get older and the more fat weight you gain, the slower that metabolism gets because it starts to get used to not working as hard, so now how do we speed that up? The answer is adding weight training into your routine.
Essentially your muscle mass that you have acts as a spark that ignites your fat burning furnace. The bigger the spark and the more you put onto it, the more fat you burn. This is why you see really big bodybuilders with a ton of muscle look pretty lean throughout the year even when they do not compete and why you see athletes looking the way that they do, especially football players.
In order to sustain hits and provide enough force on the field, they need to pack on muscle and size, When you see them shirtless, you notice how lean they actually are and how some even have abs, this is why.
Now, I know I used bodybuilders and football players to help to describe this, but this does not mean that you will gain a bunch of muscle once you start lifting weights as there is so much more to gaining weight than just touching them. You need to make sure you eat enough, have god levels of testosterone, proper sleep and recover, and then progressively making the weight heavier. For women specifically, unless you use "supplements" that are not easy to come by, you will look to gain good muscle, but never be too muscular.
Take into account Gal Gadot, Scarlet Johansson, Brie Larson, and most other action women in the movie industry that played superheroes on the big screen. You can find that they did some sort of weight training in order to look the way they did for the movies, and they are not big muscular women, but have a physique desirable to most women.
It is just important to remember that touching weights does not mean that you will instantly blow up in size, but rather will help you decrease your fat mass and help you expedite your fitness goals and get you to the desired look faster!