Long-term inactivity can “profoundly” increase blood sugar levels even when restricting food intake, according to a new study that involved 20 men lying in bed for two months straight.
The findings, published recently in the journal Clinical Nutrition, revealed the dangerous long-term impact of inactivity on the body’s metabolism that may also have implications for future crewed space missions.
In the research, 20 young and healthy male participants stayed in bed for 60 days straight while scientists, led by those from the University of Bath in the UK, assessed their health measures.
The participants stayed in bed even while they ate, showered, and went to the toilet, and were also fed a much-reduced diet to stop them from gaining weight, as scientists determined how well the men’s bodies controlled blood sugar levels.
Even when their food intake was reduced to match their much lower energy expenditure, the study found that the men’s inactivity “negatively and profoundly” impacted their blood sugar levels.
The average blood sugar levels among participants increased by around six per cent during the day, and by 10 per cent at night following the bed rest study.
The ability of their body to take up blood sugar into muscles also decreased by nearly a quarter, scientists say.
Researchers say the participants were “struggling” to control their blood sugar – an important risk factor in developing diabetes and heart disease.
Had the men not reduced their calorie intake during the course of the bed rest study, scientists speculate their blood sugar concentrations would have risen even higher.
The new findings have major implications for future space missions and for the millions of people who face periods of long-term inactivity due to poor lifestyles, chronic conditions, ill health, or injury, researchers say.
“Our results reveal that the withdrawal of physical activity profoundly impacts physiological health over and above the impact of controlling diet,” Dylan Thompson, who led the study at the University of Bath, said.
“This shows that adjusting diet alone sadly cannot overcome all the negative effects from reducing physical activity – even if you manage to avoid gaining weight,” Dr Thompson said.
Researchers are hoping to develop countermeasures for bedbound people on Earth as well as those going into space.
Recent studies suggest electrical stimulation of leg muscles may help recreate some of the effects of exercise on the control of blood sugar.
“Even in extreme cases where individuals have lost movement completely, we believe there are exciting technological options that could impact muscular contraction for blood sugar control which we are keen to explore and develop,” Dr Thompson added.