It’s fairly normal to suddenly find hangovers are a big problem as we get older… it feels like one day you’re able to go out, knock back a hideous amount of booze, then bounce back the next day ready to do it all over again… and all of a sudden those two pints of beer create the hangover from hell.

Not sure about tolerance though. What country are you in… is it easy / cost effective to get a liver test done? It might be down to lots of perfectly natural factors… if you lost weight; if you have a different diet (some foods ‘soak up’ alcohol better than others and cause it to be absorbed more gradually, if you’re drinking on a salad instead of say, pasta you’ll see a difference); you could be drinnking different beers.

Also, if you’ve had significant weight gain, this causes your liver to get fatty, which puts a strain on it; I’m not a medical professional but would think that could have an effect too.