Did you know that an average-sized man burns about 65 calories during a half-hour of vigorous sex? Not all that impressive.
But if he were to talk on the phone during sex, the total hits 100 calories. Watch TV, talk on the phone and have sex at the same time then he's burned a total of 150 calories in that half-hour. Talk about interval training!
There are more sensible uses for calorie calculators, which give ballpark estimates for various activities based on the exerciser's weight and time spent -- sports such as golf, skating, karate and skateboarding, and everyday tasks such as cleaning house and shopping.
Here are a couple of online calorie-burn calculators to check out:
Healthy Weight Forum (70 activities)
Health Status (115 activities)
Internet Fitness (70 activities)
Your mileage will vary. A lot.
As for that sex estimate, let Cosmo U.K. show you ladies how to "Have 400 Calorie Sex."
More from the fitness blog: "How to have a T-errific Sex Life"
Back in April, we looked at the health benefits of sex.