When it comes to avoiding a hangover, we've all been told to hydrate, hydrate, hydrate AND to never drink on an empty stomach.

You also may have heard that darker alcohols could give you a worse hangover — and Chief of Gastroenterology at Penn Medicine Princeton Health, Dr. Anish Sheth, is here to explain why.

"There are these chemical compounds called conjoners," the gastroenterologist explains, "which are normal byproducts of the fermentation process."

"Darker alcohol — like red wine, scotch, whiskey and bourbon — will have higher levels of conjoners. "[They're] more likely to cause hangovers the following day," he continues. "Clear liquors — like gin and vodka, for instance — are less likely to have these compounds and less likely, therefore, to cause hangovers."

And yes, on top of that, the doc can't stress the importance of hydration and eating enough either. 

WHAT CAN I DO TO PREVENT A HANGOVER?

"Hydration is more than 50 percent of it," Dr. Sheth stresses. "Alcohol is a diuretic. It causes us to lose a lot of fluid in the urine. Drink a glass of water for every alcoholic glass you have."

"Make sure you have something in your stomach," he continues, "[like] a carbohydrate-rich meal to help absorb the alcohol. If you have no food in your stomach, your blood-alcohol level is going to spike."

If you have food in your stomach, though — like the two slices of bread Dr. Sheth used to demonstrate the absorption rate — "the alcohol will be released into your system at a much slower rate." 

WHAT ARE THE BEST FOODS FOR A HANGOVER?

What can you do after the fact if you're a darker alcohol fan and are hungover? "Eggs are a great next-day breakfast meal," Dr. Sheth suggests. "Not greasy eggs, but something nice and dry. Eggs contain something called cysteine. Cysteine actually can help counteract the effects of conjoners."

Other options? Dry toast, foods rich in potassium (like bananas) and electrolyte drinks. In short, "avoid greasy foods," Dr. Sheth stresses.

Remember to always drink responsibly.