“I'm not seeing any results.”

You have been exercising for 3 months to try to lose weight, but you haven't lost much weight. You're telling someone about this problem. You say:

I'm not seeing any results.

see results

To "see results" means to have positive effects from your actions. It's often used to talk about exercise and dieting:

If you put in 6 months of good training, you'll see results.

I'm not (doing something)

You can use the phrase "I'm not ___ing" to talk about a situation that continues for some time. In the example above, the speaker is exercising every week, but she hasn't lost weight. So she says that she's "not seeing" results.

The speaker could also say, "I haven't seen any results" but that sounds a little like she's already decided to stop exercising. "I'm not seeing any results" sounds more like she's searching for a better way to exercise.