Nutrition on the Job Site: Why Sugar Makes You Tired (and Packs on Pounds)


  • Consuming sugar triggers the feel-good hormone dopamine, which is one reason you might crave it more.
  • Fructose that can’t be metabolized by your liver turns into fat.
  • Take the edge off carbs (sugar) by food combining; consume sugar with proteins or fiber.

That soda you always drink with lunch or that Snickers bar you down at two p.m. to fuel yourself for the rest of the day—is that really working out for you? Or do you feel hyped up for a while, then want to curl up in the nearest patch of sun and zonk out?

Why do so many of us get burned by sugar? And why do we keep coming back?

Why Sugar’s Hard to Avoid

If you’re like most of Americans (and most of the world), you’ve got a nice little love affair going with sugar. And since consuming it triggers the feel-good hormone dopamine, it’s no wonder. Modern culture has gone bonkers for the sweet stuff. Soda and sweet sports and energy drinks are by far our biggest sources of added sugar. And as a relatively recent addition to the human diet, they contain way more sugar than evolution has prepped us for.

Constant and massive sugar intake is a risky business.

The Dark Side of Sugar

Chances are you didn’t actually spread that Coca-Cola out over the whole day, so that ginormous sugar bomb is going to hit your system hard.

Both table sugar and high-fructose corn syrup are about half glucose, half-fructose. That means  anytime sugar is added to a food, it’s heavy on the fructose. Your liver is the only organ that can metabolize fructose—and what it can’t work its magic on becomes fat.

“But isn’t fructose the good stuff found in fruit?” you ask. Sure—but fruit also contains fiber, which works like a time-release on the fructose. Besides, there is much less sugar in an apple than a Coke.

Then, there’s all the glucose you have just ingested. Your body churns out insulin (the sugar taxi) to carry it from your blood to your cells—which sends you into that sleepy state also known as “3pm”.

“There’s a delay between when you stop consuming sugar and when you stop secreting insulin,” says Tiffany Chag, registered dietician at the Hospital for Special Surgery in New York. “This lag can result in insulin moving too much sugar into the cells, and it can leave you feeling tired.”

The Carb Double-Whammy

The sugar-smuggler that’s conspiring with your soda or dessert to give your body a double-whammy right after lunch time? Carbs.

Carbohydrates like bread and potatoes (think french fries) have a high sugar content and little fiber, so they just add to the quick and zany blood sugar roller-coaster.

“When there’s no fiber or vitamins to slow it down, your body burns through the calories from sugar much faster,” says Chag.

Sick of Sweets

You’d probably rather not know what this kind of sugar does to your body long-term. Nothing is certain, but what we can tell you is that constant and massive sugar intake is a risky business.

Firstly, as it’s already been mentioned, the fructose from soda and other desserts that your liver cannot shore up turns to fat and can lead to obesity. The other not-so-teensy issue is that after insulin has done so much yelling at your cells to take sugar from your bloodstream, the cells can get tired and stop listening. “Diabetes is the result of elevated sugar in the blood, because insulin isn’t working the way it should,” notes Chag.

What To Do

So how to take the edge off your sugar crashes without giving up your beloved soda or Skittles?

“Have two eggs with your juice in the morning or a beef jerky with your Coke,” suggested Chag. That way the protein and fiber will spread out the sugar intake—and your energy.

You also might want to think about dialing down your sugar romance a few notches. The American Heart Association recommends that men eat no more than nine teaspoons of sugar a day, and women no more than six. A 12-ounce soda alone contains about 10 teaspoons of sugar (45 per cent glucose, the rest fructose—but we’ll get to that in a minute).

You also might want to dial down your sugar romance. The American Heart Association recommends that men eat no more than nine tsp of sugar a day, and women no more than six. Click To Tweet

“Good deal!” you guys might say. “I’m just a teaspoon over.” For that to work out, you’d have to cut out all other foods with added sugar. And, let’s face it, sugar has been snuck into every processed food we eat. For instance, a bowl of Special K has three teaspoons; one dollop of ketchup has a teaspoon; and a Milky Way—nine teaspoons. And pretty soon you’re at more than double the recommended limit.

So if you feel like you need something sweet, you’re better off with a peanut butter and jelly sandwich than cookies and a Big Gulp. Sure, jelly isn’t real fruit—but PB and J offers a perfect carb-and-protein combo. “I recommend it for after a workout or other exertion,” says Chag.

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