It is much like any other diet really.
Protein to help with muscle loss
Build up to drinking 2L of water if you can (some do more) - helps with any constipation and generally good to keep hydrated
Some people struggle with too many carbs, high fat, fizzy juice, alcohol, anything sweet, spicy - others are fine - you need to play it by ear for yourself
More walking and strength training is ideal if you can sustain it. If you can do more, it will benefit you in the long run.
If you are calorie counting work out your TDEE through the TDEE calculator . net to find out what your calorie deficit should be. Recalculate your TDEE every month/pen as it will reduce as you lose.
If you respond immediately to the medication you might find it hard the first couple of week to eat enough calories. Try to get some in with calorie dense low volume foods such at mixed nuts, or you might start to feel a bit wobbly or hit problems with hair loss etc from too rapid weight loss.
If you don't respond immediately to the medication don't get too disheartened, some people have to move up to higher doses (after a min of 4 weeks on each dose) before they feel any effect, but it will hopefully come eventually.
Apps like My Fitness Pal (free) and Nutracheck (paid) can help with tracking calories. Do this over a week, as some days you will probably eat less/more.
There is a >5st to lose thread where some of us with a bit more to lose and so will take longer to get there hang out, all newcomers welcome - www.mumsnet.com/talk/weight-loss-injections/5290678-mounjaro-wegovy-with-5st-30kg-to-lose-thread-6?reply=143086634