Well, a new study does suggest that soaking in a hot bath could burn more calories than you may think.
An hour long bath burns roughly 130 calories, which is about the same number burned on a 30-minute walk, according to research conducted by exercise psychologists at Loughborough University.
For the study, researcher Steve Faulkner monitored the amount of calories burned by a small sample group of 14 men as they bicycled for one hour, and then compared it to records of how many calories were burned by members of the study during an hour-long soak in 104-degree water.
While the internet has jumped at the possibility of a totally sedentary activity producing results similar to a more active option, it's important to recognize that calories burnt inactively do not support muscle growth or many of the other benefits provided through cardiovascular activities.
"The only reason that the body would be burning calories is that hot water would increase thermoregulation to keep the body cool," said Pete McCall, Ph.D, L.A.-based exercise physiologist, to Glamour. "The hot water could dilate the blood vessels and increase circulation; we burn five calories per liter of oxygen consumed — if we can increase oxygen consumption we can increase calorie burning. Maybe taking a warm bath increases oxygen flow from deep, relaxed breathing."
The study found blood sugar levels to be similar following each activity, but did discover that the peak blood sugar level following a bath was 10 percent lower than comparable levels taken after bicycling.
“It seems that activities that increase heat shock proteins may help to improve blood sugar control and offer an alternative to exercise,” said researcher Steve Faulkner. “These activities – such as soaking in a hot tub or taking a sauna – may have health benefits for people who are unable to exercise regularly. Hopefully, our future investigations, coupled with those of other groups worldwide, will help to establish the true potential of passive heating as a therapeutic tool.”
However, if you're considering taking on a new diet or exercise plan, it's usually best to consult with a medical professional first.