Well with the crusade against smoking and the reluctance of doctors to prescribe sedatives, people have to turn to something to help them get through an often unrelenting life of misery and/or poverty and/or grind.
Human beings have needed and sought solace in various substances since the start of time. Difference between then and now is that many no longer have the anti vaxxers much prized Freedom to choose their source of comfort.
Guess what causes a much earlier death than smoking, drinking, and overeating? Street homelessness. Average age of death is 40s.
You want to deal with obesity and alcohol overuse? Then go to the causes.
Poverty.
Mental health issues - both the actual mental illness, and some of the modern psychiatric drugs used to treat the illness. The public health housing emergency.
Oh - and repairing the damage done by successive governments (both sides of the political divide) decades long underfunding and mismanagement of the NHS. Because many people are overweight due to undiagnosed, late diagnosed, or misdiagnosed physical health conditions (that can cause weight gain), and because of long waits for treatment leaving people languishing in pain and less mobile.