Trouble having effect of alcohol

Hi. I’m not an alcoholic but i really enjoy the effect of alcohol. When i drink at the weekend evening i can drink many beer 7,5% without even geting small effect. To be real, equal to A whole 70cc whisky 40%. But at lunch time just 1 liter 7,5% beer has a LOT of effect. I never drink before 3 hours after eating whenever it is anyway. Isnt this wierd?