When total caloric expenditure is held constant, combining localized resistance training with aerobic exercise does not result in greater regional fat loss compared to aerobic exercise alone.

Study: Aerobic, resistance, or combined exercise training and cardiovascular risk profile in overweight or obese adults: the CardioRACE trial

When people exercise the same total amount of time, doing both lifting weights and cardio burns the same amount of fat as doing just cardio alone — adding weights doesn’t help you lose more fat in specific areas.

Study: Effects of aerobic, resistance, and combined exercise training on body fat and glucolipid metabolism in inactive middle-aged adults with overweight or obesity: a randomized trial

The study found that just doing cardio burned fat just as well as doing cardio plus weightlifting, even though both groups exercised the same amount. So, adding weights didn’t help lose more fat from specific areas like belly or thighs.

Study: Spot reduction: why exercise probably can’t help you target fatty areas of the body

You can't burn fat just from one part of your body by doing exercises that target that area—even if you do lots of sit-ups or arm curls. Fat loss happens all over your body when you burn calories, not just where you exercise.