Choosing an initial Tirzepatide dose for maintenance

Half a milligram seems quite low. I probably wouldn't begin below 2 mg. The usual starting amount is 2.5. Your call, but doing 2 or 2.5 once a week would be simpler. Try that for the first week, then adjust up or down based on how it goes.

Given how sensitive you were to reta, starting lower could make sense.

I respond strongly to these meds and the first 2.5 mg hit me hard. Even after a year and a half I have never gone past 5 mg. Starting small to test your reaction seems sensible because everyone handles it differently.

Since you are only looking for maintenance and want to avoid feeling ill, beginning low sounds reasonable. I started at 1.25 mg and it worked fine for me; 1 mg might have been enough. I raised the dose slowly, never more than 0.5 mg at a time, to limit side effects.

I have stayed at 2.5 mg since I began a month ago. I could probably have used less but have not needed more. The usual schedule says to increase, yet there is no requirement. I add a small amount of Reta for the glucagon effect, but I could drop the Tirz lower. Two milligrams seems reasonable, and if you are very sensitive it never hurts to try a smaller amount first.

I would replace 0.25 mg of the old dose with Tirz for a week, then move to 0.5 mg, then 0.75 mg. Once you are fully on Tirz you can fine-tune the amount.

You reached goal weight with a very low amount of Reta, well done. I have switched from Tirz to Reta before and expect to go back at some point. You are using Tirz mainly to manage appetite and food noise. Keep in mind the injection peaks around 24 hours later. Start with your 0.5 mg plan, wait and see how you feel, then take another dose when appetite or food noise returns. Track everything and let your appetite guide the timing instead of a fixed schedule. Once you know what works, build a routine around it. For me food noise returns before actual hunger does.

A coworker tried Tirz for the first time at 2.5 mg this week. He felt sick that night with heartburn that kept him awake, but felt better by day three. Responses vary a lot. Trying a lower amount first lets you see how you react before committing to more.

Update: I am on my third 0.5 mg dose twice a week. Food intake has not decreased at all. The only side effect is unpleasant burps the day after the shot, then it feels like I took nothing. I will move up to 0.75 mg twice a week starting tomorrow. I want to avoid going too high too fast, and with the half-life the Sunday dose still adds a little. I could not tolerate the flat feeling on Reta but I miss how quickly and strongly it worked. My metabolism felt completely controlled. Still, feeling normal on Tirz so far might turn out to be the better option.

Update: Now at 1 mg twice a week and Tirz is not doing much. I ate a full burger and fries dinner plus a giant cookie with milk, though the cookie left me feeling sick. I miss the lack of interest in junk food. For the next dose I am going straight to the usual 2 mg.

This advice might come a bit late, but another possibility is simply lowering your Reta dose to see if the anhedonia improves.