How much is too much Halloween candy?

Four percent of the candy eaten by Americans in an entire year is eaten in one night — on Halloween.

And the average trick-or-treater’s bag contains about 60 pieces of candy, breaking down to three cups of sugar and one-and-a-half cups of fat.

All of that sugar can have some scary side effects.

Doctors warn that eating too much candy in one sitting can increase blood sugar and heart rate levels.

ABC 17’s Dana Clemens put it to the test. She went to Providence Urgent Care to get her blood sugar levels and heart rate tested before and after eating 10 pieces of candy. According to doctors, that is an average amount for kids to eat on Halloween night.

Before she ate the candy, Clemens’ blood sugar level was at 75 milligrams per deciliter, and her heart rate was 83 beats per minute. Both of these numbers fall within the normal range, according to physicians.

Then she ate the 10 pieces of candy and waited one hour. When she went back, her results surprising.

Clemens’ blood sugar rose to 112 mg/dL. The cutoff for healthy blood sugar is at 120 mg/dL.

Her heart rate had also skyrocketed. It increased to 103 beats per minute, which is three beats over the normal range.

Doctors say those issues are concerning, but the long-term issues are an even bigger worry.

Doctors say fat deposits from eating candy frequently can lead to childhood obesity.

Dr. Jason Zerrer said the key to making sure your child stays healthy is moderation.

“It’s a social holiday, a one-time event, and the important thing is treating it like a one-time event,” he said. “It’s like a vacation, so don’t make a habit of this type of eating.”

Dr. Zerrer does not have a hard and fast rule about the amount of candy a child should be limited to in one sitting because each child digests it differently.

But consider this: each “fun-size” candy bar contains 60 to 100 calories.

While sugar is a big concern, Dr. Zerrer there’s another ingredient parents should be on the lookout for: high fructose corn syrup.

That corn syrup is in many of the popular candies, including candy corn, Skittles, M&Ms, Twizzlers and lollipops.

Reeses Cups, Kit Kats, Hershey’s Dark Chocolate and Dove Chocolate are candies that do not have the corn syrup in them. While they are harder to find, Dr. Zerrer said it’s important that parents try to limit the amount of high fructose corn syrup their child eats.