CLEVELAND -- The latest way to help you lose weight just made its way to northeast Ohio.

Can you guess how many calories you eat in a day, or how many you'd have to cut in order to shed some pounds?

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5 On Your Side health reporter Alicia Booth reported that a new device can take some of that mystery out of weight loss.

It can work for people who have had gastric bypass or those who just want to lose a few pounds.

Dawn Beljin's battle with weight is a familiar one. At 36, she longs for her thinner days because ever since she had a baby, things just haven't been the same.

"I was always fine with my weight up until I had my daughter … and since then, I've had these probably 30 pounds of unwanted weight," said Beljin.

Despite her battle to cut calories, Beljin just can't win the war.

"I've dropped 5, 10 pounds, maybe up to 15, and then I seem to gain it right back," said Beljin.

That's why she's a good candidate to try a new weight loss device, the new metabolism tester at the Northern Ohio Bariatric Center, at Parma Hospital.

Exercise physiologist Bob Hetzel discovered the Medgem and brought it to Cleveland.

"It takes the guess work out of the equation," said Hetzel.

The device will show patients what their resting metabolic rate is, how many calories they're burning just by living and breathing.

"We can say you have to reduce your diet by 500 calories, but what are we reducing that from? Now we have the X-factor. This is the number we need to be subtracting those calories from to create weight loss," said Hetzel.

The device measures expired oxygen while the patient breathes into it for about 10 minutes.

When Beljin used the device, she got a few big surprises.

At 5 feet 1 inch tall and 150 pounds, she's not eating nearly the calories she thought she was.

The Medgem showed, without accounting for exercise, she's taking in only 1,390 calories a day, 1,668 if you count how much she moves around at work.

And based on the numbers they calculated and her current weight, she found she didn't really need to lose those 30 pounds.

But the doctors agreed that 10 pounds would be OK, at half a pound a week, and that means cutting only 250 calories a day.

"I truly expected to walk out of here with him telling me, 'You're right, you do need to lose that 30 pounds,'" said Beljin.

Beljin took the test about three weeks ago and lost at least a couple of pounds.

She said taking the test was a good motivator.

In some cases, insurance may cover the metabolism test. To take the test at Parma Hospital will cost about $50.

If you would like to find a facility near you that provides metabolic testing, click here.