After four weeks, the average weight loss is around 2% of body weight; after eight weeks, it's over 4%. Mounjaro (tirzepatide) reduces appetite and hunger, helping you eat fewer calories; this effect is almost immediate.

However many people begin losing weight way earlier, typically within a few weeks of starting the injections, because they notice an immediate reduction in appetite. Others may require higher doses to see these effects. One study showed an average of 6% weight loss after 2 months.