Everyone knows the golden rule of losing weight: You have to burn more calories than you consume. And even though some may keep meticulous track of calories they consumed, very few know exactly how many calories they burn in a day.

A new line of electronic monitors hopes to provide a solution to that problem. These devices can accurately gauge physical activity – including calories burned – to help calorie-counters in their quest to lose weight.

The New York Times recently offered this sampling of the new monitors:

• The Striiv ($100). A simple touch-screen device about the size of a cell phone goes where you go and measures your steps when walking, running or climbing stairs, providing a measure of calories burned. It ‘awards’ the user with virtual trophies and points for record number of stairs climbed, for example. It may occasionally challenge its user to “Do three minutes of activity.”
• Fitbit ultra wireless activity tracker ($100). Like the Striiv, it measures calories burned by counting steps when walking, running or stair climbing. It can also track the amount of time and quality of your sleep, and it allows you to record what you eat to count calories consumed as well.
• Bodymedia fit link ($200 + subscription). Worn on the upper arm, these devices measure heat, moisture and movement to count calories burned – but just for walking or running. It measures sleep time and quality, and allows you to count calories consumed. Its nutrition assessment component analyzes the quality of the food you’ve eaten in the past three days.
• Motoactv ($250 to $300). This counter comes with a built-in GPS receiver and can be combined with a heart monitor to record a wider range of activities. Users specify the type of activity on its touch-screen, then start a timer. It also offers a musical playlist to accompany workouts.

Despite the high-tech assistance of these calorie-counting devices, their success still hinges on a basic premise: that they be consistently used. Still, perhaps all the bells and whistles will be intriguing enough for gadget lovers to stick with it this time.