Every so often someone announces they've given up drinking for a month. They mention it a lot. Annoyingly, the data suggest they may be onto something.
What researchers measured
The best-known study appeared in BMJ Open in 2018. Researchers in London followed 94 moderate-to-heavy drinkers who stopped for a month and 47 who carried on. The first group's insulin resistance, a warning sign for type 2 diabetes, fell by about 26%. Systolic blood pressure dropped by about 6.6%, and weight by about 1.5%. The group that kept drinking saw no significant changes, and the improvements weren't linked to changes in diet, exercise or smoking.
Two growth factors tied to cancer also fell sharply. That doesn't show a month off lowers cancer risk. They are markers, and the study wasn't designed to measure that.
What people notice
A University of Sussex survey of Dry January 2019 participants found that 72% slept better and 84% saved money, which may be the fastest result of all. Six months later, they were still drinking less than at the start of the year. So the feared February binge generally didn't happen.
The fine print
People weren't randomly assigned in the BMJ Open study; they chose which group to join. So it can't prove cause and effect, and it can't say how long the benefits last. It also left out people with known alcohol dependence or liver disease. If you drink heavily every day, talk to a doctor first, as stopping suddenly can be dangerous.
Your liver won't send a thank-you note. It has about 500 other jobs, as Alcohol Change UK points out.