If you train 3 or 4 times a week, and if you maintain a balanced diet, Taekwondo can help with losing weight.
Losing weight is complicated. Central to losing weight is maintaining a balanced diet – not eating too many highly-processed foods, not eating too much sugar, eating plenty of vegetables, and so on. Getting the right amount of sleep is also very important. Exercise is only one part of losing weight.
The most important aspect of exercise when trying to lose weight is doing enough exercise. Regardless of what sport you decide to do, the most important thing is that you do intense exercise at least 3 times a week (4 times a week is good too, but there’s no need to do it 5 or more times a week).
Taekwondo is excellent for general fitness. It improves your general aerobic fitness and stamina, but because of the difficult kicking techniques involved, it also improves your strength, balance, and coordination.
If you’re looking to start Taekwondo in order to lose weight, it’s important to choose the right class. Some classes may be more focussed on self-defence training, which is generally not a high-intensity activity. Sparring is probably the most energy-intense activity in Taekwondo, so choose a class that does a lot of sparring, or a class that incorporates a lot of fitness activities into each lesson.