When you want to lose weight cardio is the first advice, right? However there is one big misunderstanding when it comes to cardio.
Cardio burns much less calories than you would think. The cardio sensors on the machines are usually wrong and not very accurate way to measure how much calories you are burning during cardio sessions. Actually it's almost impossible to know exactly how much calories you are burning during cardio manifests.
Our body wants us to survive
The body does not give a singular fuck about how much muscled or ripped it is. Truth. The body gives however a lot of attention to surviving each day. That and the fact that in nature nothing is ever lost is the reason why extra caloric intake is stored as bodyfat.
The body is very efficient when it comes to burning fat and uses just as little as needed. In other words if we were burning 5000 calories everytime we walk for 5 miles we would simply die becuase this is not efficient and one of the reasons why we burn much less calories than we think during cardio.
Think for a second: if in an hour of cardio you burn 500 calories you have actually used much less extra calories because out of those 500 calories 250 would have been used just to live during that hour. In other words the reward is smaller and if you eat one banana the reward is gone. That's why diet is more effective for burning fat than cardio and faster results are seen from it.
When you introduce 500 or more caloric deficit to your daily intake your body is receiving 500 calories less no matter what. You have a calculated, pure and real caloric reduction and you did not have to sweat like a pig to achieve it.
With that being said cardio comes with other benefits diet will never provide - reduction of excess water, improved cardio vascular system, improved agility, stamina...etc.
Conclusion: Diet is more effective than cardio for losing weight but cardio still offers a lot of benefits outside the fat burning spectrum.