It is possible to get results by working out at home, but it is harder than at a gym. The reasons have to do with the equipment available. Unless you spend a lot of money, the gym will have better equipment than you do at home. This is an advantage for variety, which helps with your motivation, provides a better environment for the muscles to grow, and is more attractive to friends who will make your workouts easier and keep you motivated.

If you know exactly what you want to do, you can get the exact piece of equipment on which to do it at home. But will this be the right equipment next week, or next month, or next year?