You will look spindly if you remain sedentary and eat fewer calories, yes. Importantly, you can eat the same amount of food if you eat things that aren't laced with sugar and have higher fiber content. This is a good rule of thumb for cutting the excess calories when you're first starting out.

The trick is to metabolize the food you eat. You do that with exercise, primarily cardio. Then your body's new homeostatic program also involves "supporting the frame of the body during physical movement" and you begin to develop some muscle, preventing the emaciated look.