Most local Indian places will do you a solid 1500 calorie meal for £10 if you know what to look for.
Versus, go to supermarket... get stuck in a routine every day of "buying stuff", wanting snacks, meat, and so on adds up quickly to the point where sticking below £10 a day becomes a constant battle. It's the routine and constant food noise that really got to me, and when even a chocolate bar can be 10% of your budget for a day the decision fatigue is real.
So by breaking the routine, sticking to OMAD, I lost weight, had much less decision fatigue, and no constant food noise - that was the major change that saved me a load of money, time & effort.
For example yesterday I found a tiny cantonese place, got wonton soup and some duck, vegetables and watermelon for about £8