After a 22 year gap I finally got 1st Dan and dropped 20kg from 2014! Ok so Karate is not for everyone but here is a couple of reasons it helped me:
I did not pick a macho bullshit style. I studied Traditional Shotokan which was fo used on self development and not on breaking boards and sporting success. So balance, suppleness and focus were key. Karate is for life, not for the ring and a short career.
There is a high emphasis on Kata, the set routines like dances/shadow boxing. It keeps you moving and on the go no matter what your age, fitness and weight.
2nd I could do other things. Karate is both an individual and team sport. It is one of the few there are. I can do Karate on my own and with a club. Also I can partake in other sports and still practice Karate on my own in my own time and not lose anything or interfere with my commitments.
3rd there is a strict grading system every 4 months. This meant I could set clear targets and goals throughout the year! Did I want to lose 2kg by the next grading, that was my goal plus pass the grading. Did I want to learn my kata backwards in the next 3 months? That was my goal. Did I want to jog a km in a average of 6.30minutes by the next grading? And so on... I had 4 clear markers every year I could not avoid to notice if I wanted to progress in my martial art and I used those markers to set and measure my goals by.
During this time life has gone up and down plus so has my weight. But even though I would recommend Karate as a great way to help you lose weight, it is not really because you get super strong and super fit in the process of doing Karate. It's the additional stuff you do that really burns the fat, the running, diet etc. Karate sets goals and brings martial disapline. That is priceless when losing weight!