How Many Calories Do You Burn Diving?

Recently, we came across an article in Shape that scuba diving was the newest celebrity fitness trend. We were interested to know that Sandra Bullock and Katie Holmes love their new underwater workouts. We were even more curious when the story said the average woman could burn up to 400 calories in just 30 minutes, and that it's not uncommon to burn 500-plus calories during one workout.

And according to the website CalorieCount.com, a 150-pound person can burn 475 calories per hour, equivalent to burning off either a McDonald's Big Mac with cheese, six glasses of wine, or 1.7 Snickers candy bars.

We've always debunked the notion that diving is a high-intensity sport because one typically moves so slowly underwater. But with all these places touting 500-calorie workouts, we had to find out if they were right and why. So we went to the American College of Sports Medicine (ASIM), which produced Allan Goldfarb, an exercise physiologist who teaches at the University of North Carolina, as its expert source. He says that a wide range of activities are measured in metabolic equivalents (METS), which is the ratio of the work metabolic rate to the resting metabolic rate. One MET is defined as 1 kcal/kg/hour, roughly equivalent to the energy cost of sitting quietly. In the "Compendium of Physical Activities," co-created by the National Cancer Institute, scuba diving has an average level of 7 METS, although "moderate" diving has 11.8 METS, and "fast" diving has 15.8 METS. (Compare that to leisurely swimming, which has 6.0 METS, and "general jogging" which has 7.0 METS.).

"The range of oxygen usage in one's maximal aerobic capacity, or VO2 max, is from 25 to 50 liters, so for the diver, it depends on the velocity of movement, the rigidity of the fin, if they have a wetsuit on (that adds weight and drag) how big the tank is, and the diver's experience," says Goldfarb. "The increased energy demand is placed on breathing above normal to move the air, and with greater resistance to the movement needed to overcome water resistance . Thus the higher energy cost."

A newbie diver will probably burn more calories than an experienced one, as the former may flail through the water with all body parts moving, and struggling to keep up with someone who glides easily through the water. No matter your experience, keep in mind you are using your whole body when swimming against resistance (what makes it less strenuous is the fact that you are partially suspended). Compare that to traditional weight lifting -- you're working single body parts at one time, resting and sitting between sets and using only one part of the body for 10-20 seconds at a time -- which simply does not burn many overall calories.

As PADI communications director Theresa Kaplan told Shape, "Scuba diving provides a full body workout that combines cardio and strength training to burn calories, tone muscles and even improve breathing. Maneuvering through water requires constant motion by your entire body, thus toning and strengthening muscles in your thighs, shoulders and your core."

So we stand debunked, but still skeptical. How is it that so many people write to us to complain that they gained five pounds on their last dive trip?