Adults who sit for more than 30 minutes at a stretch face a higher risk of dying from cancer, even if they exercise regularly, according to a new analysis of UK Biobank data. The observational study found that breaking up sedentary time with light activity—standing or walking for a minute or two every half hour—was associated with a relative risk reduction of up to 20%. Researchers excluded cancers diagnosed in the first two years to reduce the chance that undiagnosed illness was causing people to sit more, strengthening the case that prolonged sitting itself contributes to poor metabolic health.

A separate randomised trial, published in the Annals of Internal Medicine, provides direct evidence that even modest sleep restriction can cause weight gain. Ninety-five adults who usually slept at least seven hours a night were asked to cut their sleep by 1.5 hours for six weeks. They experienced a small but measurable increase in body weight and waist circumference, and spent more time sedentary. The findings suggest that chronic sleep loss, common in modern societies, may be an underappreciated driver of obesity, particularly in people already at risk of cardiometabolic disease.

Meanwhile, a meta-analysis of 21 randomised clinical trials, led by researchers at Tufts University in Boston, found that artificial sweeteners are not metabolically inert. Compared with water or placebo, consumption of these sweeteners was linked to higher fasting insulin levels and elevated HbA1c, a marker of long-term blood sugar control. There was also a trend toward reduced insulin sensitivity. The authors hypothesise that changes to the gut microbiome may mediate these effects, though they caution that more research is needed to establish causality.

These findings arrive as regulators in Sweden warn that a dietary supplement called Insulinorm is being illegally marketed as a diabetes treatment, exploiting patients seeking quick fixes. The accumulating evidence on daily habits is expected to inform updated guidelines on physical activity and dietary patterns, with longer-term trials on sedentary behaviour and sweeteners already underway.