Doctors Explain Why Sugar Can Make You Literally Feel Hungover

Why brownies or a big açai bowl can make you feel like you’ve been out partying.

by JR Thorpe
A line of donuts. Are sugar hangovers real? Doctors explain what's behind the phenomenon.
Jennifer A Smith/Moment/Getty Images

After just two — OK, four — cheesecake brownies from your newly reopened neighborhood bakery, the headache hits. It's an hour later, and you just want to lie down in a dark room and never see another sugary treat again. It's worth wondering: Are sugar hangovers an actual thing?

"Sugar hangovers are a real phenomenon," Dr. Scott Braunstein M.D., medical director for Sollis Health, tells Bustle. "However, the name is slightly misleading." Regular hangovers happen because your liver and stomach are attempting to clear alcohol and its byproducts from your system, while sugar hangovers are a bit simpler. Sugar doesn't produce toxic byproducts like acetaldehyde, thank goodness, but it does pose a bit of a challenge for your body.

"When we're talking about a sugar hangover, we're really just talking about the rollercoaster ride our blood sugar takes when we introduce a lot of glucose into the bloodstream," Dr. Jaclyn Tolentino, D.O., a physician at Parsley Health, tells Bustle. Eating a lot of sweet things quickly, she says, causes rapid fluctuations in your blood sugar, which affects your brain, energy levels, and a lot of other bodily functions, including the amount of insulin your body produces to process that flood of sugar.

Insulin is a hormone that's responsible for regulating your blood sugar whenever it gets too high or too low. When you're in the throes of a sugar rush, your insulin production goes into overdrive; it signals your liver and muscle cells to start absorbing glucose from the blood, to level you out. That surge of insulin may make you a bit crabby, and bring on headaches, fatigue, or stomach issues, Dr. Tolentino says. It won't last forever; it's just your body absorbing your sugar hit, and getting back its equilibrium.

But sugar hangovers can also be quite serious. "In some people who are more susceptible, the body responds to the spike by producing a disproportionate amount of insulin," Dr. Braunsteins says. That means you might start feeling the symptoms of hypoglycemia, where there's too much insulin in the body and your blood glucose levels plummet. "The symptoms are brain fog, sweating, tremors, irritability, and fatigue," he says. He suggests eating a little more sugar to raise your blood sugar over time, until you feel normal again; if this happens a lot, or if the feeling persists, consult your doctor.

There's also the possibility that your sugar hangover isn't just about sugar; it could also be about lactose. If a slice of creamy cheesecake or a smoothie give you stomach weirdness, you could be showing signs of lactose intolerance, where your digestive system hasn't got enough of the lactase enzyme to properly process dairy. Lactose intolerance can cause a range of symptoms, including bloating, nausea, gas, abdominal pain, and weird stomach growling noises.

If you end up feeling irritable, achy, or sleepy after a big dessert or extra-sweet breakfast, it's nothing to worry about. "You can combat some of those effects by hydrating well, and making sure your next meal is rich in leafy greens and lean protein," Dr. Tolentino says. If you find that you get confused and trembly after too much sugar, though, you might want to talk to your doctor about your insulin levels and how to regulate them.


Dr. Scott Braunstein M.D.

Dr. Jaclyn Tolentino D.O.