It's important to keep active, possibly more active than you normally are. Make it a lifestyle choice so you can replace old habits. Remaining fully sedentary

It's important to keep active, possibly more active than you normally are. Make it a lifestyle choice so you can replace old habits. Remaining fully sedentary and running a 1000 calorie deficit isn't maintaining a diet, it's starving yourself. You'll get the weight back as soon as you call the diet a success and go back to your 'default' lifestyle. (This of course doesn't apply to everyone: medical reasons, disability, etc.)