I tried to lose weight by working out at the gym. It didn’t work out. Then I realised it was the diet I needed to change. So I went full carnivore, ie eating meat based products including eggs and just drinking water. I lost about 20kg within weeks. I eliminated carbohydrates from the food I eat.
This is what worked for me. As for gym workouts, they too are necessary for gaining muscle mass or converting some fat into muscle. Muscle is important as we age, to reduce falls and other benefits.