Short answer...absolutely not. But lets dive into this a little bit more shall we?
Working your cardiovascular system has been proven to provide many health benefits and is a need for many athletes and individuals. However, we are not dealing with health or performance, we are talking about weight/fat loss.
It has been richly researched that the only way to lose fat is to achieve an energy deficit. That is to say, you consume less calories then you burn. This has been proven many times. You can achieve this energy deficit with a number of different diets including Ketogenic (carb free), 2 1 diet, general calorie restriction - the list goes on. Every diet however needs to obide to this principle, otherwise weight loss/fat loss will not happen.
There are a few ways that the body uses calories for energy:
1) Exercise-associated thermogenesis (EAT) - Doing exercise/training will require calorie consumption.
2) Non-exercise activity thermogenesis (NEAT) - General activity such as walking, moving around basically any movement that is not exercise will require calorie consumption for energy.
3) Diet-induced thermogenesis (DIT) - The digestion of food also burns calories
So, as long as you create an energy deficit via these pathways, you will lose weight.
Metabolism: Metabolism describes the chemical reactions in your body. The quicker your metabolism is, the more effective your weightloss will be. BMR (Basal Metabolic Rate) describes the amount of calories you need per day to survive if you just lay in bed all day. BMR will depend on your age, weight, gender and height. Generally speaking, people do not just lay in bed all day (unfortuately I know), so extra calories are needed to ensure the individual is fuelled for their daily activity. Knowing how many calories to eat to subsidise the activity is a matter of trial and error - unless you have access to very sophisticated equipment.
When you lose weight, your metabolism (as well as many other bodily processes) will de-regulate, i.e. slow down - this is called metabolic adaptation. To ensure your continual weight loss, you must ensure your caloric intake is under your metabolic rate. This is when calorie cycling, reverse diets, re-feed days, calorie tracking, activity tracking becomes important and useful. Exercise & activity is another way to boost your metabolic rate.
Do you need to track calories to lose weight? No, but people tend to hugely underestimate their caloric intake. Tracking will ensure that you are on the right path and allows you and a coach to evaluate progress with quantifiable data, and make amendments to the programme if need be.
So, do you need cardio to lose weight? No. Cardio will help increase your EAT which will help burn calories, but that doesn't mean you need it. You can burn calories via resistance training, reduce general caloric intake and/or increase your NEAT.
Very often, hugely increasing an individuals cardio will negatively effect their other training. If your primary goal is to lose body fat, but retain muscle mass (like Matt pictured below), then performing long runs or long rows will not be beneficial. Instead, maximising resistance training & throwing in some low intesnity steady state (LISS) cardio every so often will be the better option.
If you have any questions about this subject, or anything else, please get in touch!