Is cardio the key to weight loss? I don’t think so.
When you do cardio, you breathe hard, you sweat, your heart rate goes up, and it feels like something major is happening.
Those are the same feelings many people associate with fat loss, so cardio seems like the obvious answer. 
Cardio has many benefits.
It helps your heart, improves conditioning, builds work capacity, and yes, also burns calories.
But when it comes to weight loss itself, the answer is still simple:
No, you do not NEED to do cardio to lose weight.
Should you do some? YES.
To lose weight, you need to be in a calorie deficit.
That is what matters most.
Cardio feels powerful because it is hard, but hard does not always mean effective in the way people think.
Cutting 300 calories from a 1,000 calorie dinner is just as beneficial for fat loss as doing 45 minutes of cardio, and that food decision takes almost no time.
If you think about it, you’re likely a few food choices away from cutting enough calories to equal hours of cardio each day.
If the average person eats a large dinner, especially when eating out, removing a few hundred calories from that meal can make a meaningful difference without adding any extra time to the day.
Now, that does not mean cardio is useless.
It means cardio is not the main driver of fat loss.
Calories are.
At the same time, most people do not just want the scale to say a lower number.
They want to be leaner.
They want to keep their muscle.
They want to lose fat and look toned, strong and healthy. 
If you lose weight without strength training, you are more likely to lose muscle along with fat.
That can leave you at a lower body weight without looking much different.
Losing 10 pounds while strength training and eating in a calorie deficit will look much different than losing 10 pounds through cardio alone.
That is why the best plan is not:
Only cardio
And it is not:
Only lifting weights and ignoring your food
The best plan is to strength train, eat in a calorie deficit, and use cardio as a smaller part of the program.
For most people, that is the winning combination.
Strength training should be the main event.
Nutrition should drive the fat loss.
Cardio should support the process.
Takeaways:
1. You do not need to do cardio to lose weight.
2. You do need to be in a calorie deficit to lose weight.
3. Cardio has real benefits, but it is not the main driver of fat loss.
4. Cutting calories from food is often easier than trying to burn those calories off with exercise.
5. Strength training helps you keep muscle while losing fat.
6. Losing weight without strength training can lead to muscle loss.
7. The best strategy is strength training, a calorie deficit, and some cardio to support the process.
– James Pratt