To be effective, ST needs to be challenging your muscles at close to their maximum capacity. And the more challenging, the more effective. The other thread is quite right in saying you should be fatigueing your muscles in 12 reps or less (the fewer the better).
The way you do ST is pretty much the same regardless of your objectives. What changes is the intake side of things.
So yes, if you can do 20+ reps, it is definitely time to increase the weight. But don't try a big jump - increase it by the smallest increment possible, and if you can still do more than 12 reps, increase it again the next time, until you hit a weight where you can no longer do 12 reps.
Without ST, up to 25% of your weight loss can come from lost muscle, rather than fat. As muscle burns calories even at rest, over time this lost muscle will make longer term weight loss harder. Moderate ST such as you have been doing until now may slightly slow this rate of muscle wasting, but challenging ST will slow it further. More challenging ST will also increase your calorie deficit, as more protein will go into repairing muscle tissue, rather than being burned for energy.
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.
| current weight: 178.0