No it does not work in the long term, it is absolute bullshit 'science'. Our bodies need carbs for fuel, carbs are out ENERGY. Cut them out and you get various side effects, fatigue obviously being one and bad moods soon follow.
EAT CARBS. They are NOT evil. Complex carbs I am here referring to so Wholewheat bread, pasta, brown rice, potatoes, FRUIT! Because fruit is also a carb don't forget. Bananas are a massive carb, they're also an incredible energy source.
Just cut down on shit and move your body. It's as easy as that. Don't cut out a whole food group, just cut DOWN on things that have little to no nutritional value- I include white pasta and bread in this along with the usual suspects like pizza, chinese take out, cake, biscuits, chocolate and so forth.
Try yoga, Pilates, walking, running, swimming... Anything to move and tone your body. It will come off in its own time, I promise.