Many people who’ve decided to lose weight find themselves stuck with a tricky question — should they do cardio or lift weights? They’re the two most popular types of workouts, but it can be hard to know which is a better use of your time.

Cardio burns more calories, but it’s harder to target fat loss and not muscle loss. Cardio can also increase cortisol, a stress inducing hormone. If you eat more calories than you’re burning, you’re not accomplishing anything for fat loss. If you burn more calories than you eat, you will end up losing muscle and fat proportionally. Many scientists have researched how many calories people burn during various activities. Based on this research, you can use your body weight to estimate how many calories you will burn during different types of exercise, including cardio and weight training. For most activities, the more you weigh, the more calories you will burn. If you weigh 160 pounds (73 kg), you will burn about 250 calories per 30 minutes of jogging at a moderate pace. If you were to run at a faster pace of 6 miles per hour, you would burn around 365 calories in 30 minutes. On the other hand, if you weight trained for the same amount of time, you might only burn around 130–220 calories. In general, you’ll burn more calories per session of cardio than weight training for about the same amount of effort.

With weight lifting, if you eat more calories than you burn, you could put on muscle instead of fat and still lower your overall body fat percentage. This is typical for new lifters. If you eat less calories than you burn, you can maintain your muscle composition while targeting fat almost entirely. This isn’t really possible with pure cardio. Although a weight-training workout doesn’t typically burn as many calories as a cardio workout, it has other important benefits. For example, weight training is more effective than cardio at building muscle, and muscle burns more calories at rest than some other tissues, including fat. Because of this, it is commonly said that building muscle is the key to increasing your resting metabolism — that is, how many calories you burn at rest. One study measured participants’ resting metabolisms during 24 weeks of weight training. In men, weight training led to a 9% increase in resting metabolism. The effects in women were smaller, with an increase of almost 4%. While this may sound good, it’s important to think about how many calories this represents. For the men, resting metabolism increased by about 140 calories per day. In women, it was only about 50 calories per day. Thus, weight training and building a little bit of muscle won’t make your metabolism skyrocket, but it may increase it by a small amount. However, weight training also has other important calorie-burning benefits. Specifically, research has shown that you burn more calories in the hours following a weight training session, compared to a cardio workout. In fact, there are reports of resting metabolism staying elevated for up to 38 hours after weight training, while no such increase has been reported with cardio. This means that the calorie-burning benefits of weights aren’t limited to when you are exercising. You may keep burning calories for hours or days afterward.

I’d say the approach that lets you target fat loss is better for burning fat. In a nutshell, cardio helps you burn more calories per session while weight lifting helps you burn more calories every day. 

*Cardio – Loses the most weight (muscle and fat).

*Weight lifting – Builds the most muscle (while burning fat).

Source: Quora