We're all guilty of signing up for that expensive gym membership that we hardly ever use. The last thing you want to do is slip into some lycra after a hard day at work, it can be difficult to muster the enthusiasm to even get yourself home. So for those of you, like us, who want to drop a few calories without putting in hours of gruelling effort, you'll be pleased to know it could be as easy as running a hot bath. We kid you not.Dr Steve Faulkner of Loughborough University conducted an experiment with BBC journalist Michael Mosley, comparing the relative benefits of having a long, hot bath compared to an hour of cycling.The volunteers were fitted with monitors to record blood sugar levels as well as equipment to measure the amount of calories burned.
The participants were asked to take a long, hot soak in the tub. The temperature was kept at 40°C, and their core temperatures were closely monitored. Once the temperatures had risen and stayed there, the volunteers were allowed out of the bath.Two hours later they were given a light meal.
In the second part of the experiment, the volunteers were told to spend an hour exercising on a bike. The two comparable results were then gathered.Dr Faulkner wanted to investigate if having a hot bath burned the same amount of calories as an hour of exercising.The results were as follows: 'One of the first things that we were looking at,' Dr Faulkner said, 'is the energy expenditure while you're in the bath and what we found was an 80% increase in energy expenditure just as a result of sitting in the bath for the course of an hour.
'This is nothing like as many calories as cycling for an hour (which comes out at an average of 630 calories) but we do burn 140 calories, the equivalent of a brisk 30-minute walk.'Impressive! But that wasn't all, they also found that blood sugar levels were also lower after having a bath.
'Where we started to see differences," Dr Faulkner added, 'was when we looked at your peak glucose output.'Your peak glucose output is the amount your blood sugar rises after eating a meal. This can be dangerous for those who suffer with type-2 diabetes and other metabolic diseases.'We found that peak glucose was actually quite a bit lower after the bath, compared with exercise, which was completely unexpected,' Dr Faulkner added.
In fact the volunteers' post-meal glucose levels were, on average, 10% lower after taking a bath than after exercising.Dr Faulkner suggested this could be down to the release of heat shock proteins – which help to protect your body against damage. They've also been linked to divert sugar from the bloodstream into the muscles, preventing potential damage to arteries and nerves. So whilst having a hot bath or sauna reduces blood sugar levels and burns calories, bad news – it doesn't mean you can replace exercise with a relaxing soak in the tub. Dr Faulkner recommends that you should still aim for around 150 minutes of moderate exercise per week too. Even so, if a bath means we can burn an extra 140 calories who are we to argue?