Assuming you can only go to gym once a week the below-mentioned 5 exercises will be an effective way for you to: 1) preserve muscle mass and 2) burn calories.
Muscle legs? Amazing for lower body development, hamstrings and glutes along with core.
2. Dumbbell Bench Press
3. Wide Grip PullUp
You will be hitting your lats, biceps and forearms. Pull ups target your lats better than any other exercise.
You will be hitting your lower body particularly hamstrings, glutes, lower back, mid-back, traps, forearms… actually everything – this exercise will engage your entire body.
5. Dips or Overhead Press
You will be hitting your front deltoids and triceps. If you do it standing it will actually incorporate your entire body.