It’s officially spring break season and college students are eagerly swapping their textbooks for tequila as they flock to vacation destinations across the country. Even though heavy alcohol consumption has become synonymous with spring break, some undergrads have become more health-conscious about their drinking.

Individuals who are concerned about the effects of liquor should know all types of alcohol are hard on the body. However, there are some differences between “dark” and “clear” alcohol. Here are common questions and helpful answers regarding dark and clear alcohol:

What separates dark versus clear alcohol?

In terms of alcohol content, there's no difference between dark and clear alcohol with the same "proof" or percent alcohol by volume (ABV). Alcohol proof is defined as twice the percent ABV. For example, a 100-proof alcohol would be 50 percent ABV.

Most standard "hard" liquors, such as whiskey, bourbon, gin and vodka, are around 80 proof or 40 percent ABV.

There isn't any difference in calories between the hard alcohol varieties either, as long as they are the same proof. For reference, calories per gram for alcohol and the macronutrients are:

- alcohol = 7 calories per gram
- carbohydrate = 4 calories per gram
- protein = 4 calories per gram
- fat = 9 calories per gram

So on a calorie density basis, alcohol falls somewhere between fat — a very dense source of calories — and carbohydrates and protein.

For hard alcohol with added sugar, you may end up with more calories from carbohydrates. However, you'll also end up with fewer calories from the alcohol itself, because you're diluting the alcohol and lowering the proof.

This is why the best way to "compare apples to apples" is to compare only alcohol varieties that have the same proof, or alcohol by volume.

What elements make up dark alcohol and how can they impact the body?

Dark alcohol gets its color from substances called congeners. Congeners are small amounts of naturally occurring substances in dark alcohol. They are generated during fermentation, distillation and in some cases, aging. Anything that is not ethanol — the form of alcohol intended for drinking — can be considered a congener.

Congeners include substances that give both color and unique flavors to gold and brown alcohol varieties such as whiskey (the "e" means it's American), scotch whisky (no "e" means it's from Scotland), bourbon, tequila, rum, brandy, rye and cognac. Beer and red wine also contain congeners. Examples of congeners include methanol, acetone (same stuff found nail polish remover), tannins, esters and aldehydes.

Alcohol researchers have proven congeners do not affect how intoxicated or "drunk" a person will become when ingesting alcohol. Only the ABV or proof determines how significantly an alcoholic beverage will affect or impair a person's cognitive abilities and coordination.

However, that’s not the end of the story with congeners: They can worsen a hangover.

Even though congeners occur in very tiny amounts, some of them are considered toxic. Of course, alcohol itself is toxic as far as the body is concerned, and this is why alcohol in excess leads to hangovers. Congeners don't worsen the toxic effects of alcohol, but they can add to these effects.

The result is a worse overall hangover experience after drinking dark liquor compared with drinking the same amount of a clear liquor. The headache, body aches, nausea and heartburn delivered by alcohol are worse if that alcohol also contained congeners.

What different elements make up clear alcohol and how can they impact the body?

Clear alcohols contain little to no congeners for two reasons. Depending on what you ferment — potatoes for vodka versus grains for whiskey — you may generate fewer of these extraneous substances to begin with.

Secondly, congeners can be removed with purification processes. Even if they do turn up in a clear alcohol, they can be removed before the product is bottled and sold.

Even though they don't contain congeners, clear alcohol can certainly lead to hangovers if you drink enough of it! Alcohol (ethanol) itself has toxic effects. However, compared with dark liquor, clear varieties will result in a slightly less-intense hangover, gram per gram consumed.

Many people find clear liquors taste cleaner and sharper than dark liquors, however, most of what people enjoy is a matter of personal preference and habit. As most people who enjoy alcohol know, this is often an acquired taste.

How exactly does dark and clear alcohol impact a person differently?

The main difference is how "pure" these products are. The darker varieties contain minute amounts of other substances, called congeners. The clear varieties do not contain congeners. For clear liquors congeners are not generated in fermentation and distillation or they are removed with purification processes.

The amounts of congeners in dark liquors are not significant enough to change the proof or ABV, but they do add color and flavor.

Another interesting difference between clear dark liquors is "aging." Many dark liquors are aged in a barrel or other container for many years. The alcohol mixture can interact with the container and even pick up additional substances that impart color and flavor to the finished product.

Again, these substances may taste and smell good while imparting a lovely color. But they are congeners and will add to hangover woes. As noted above, they will add to the already toxic effects of large quantities of ethanol.

Clear liquors typically are not aged, although they can be. If they are aged, again, the congeners are removed before bottling so the finished product doesn't contain them.

At the end of the day, which alcohol is better for my health?

That depends on how much a person drinks. Both alcohols can be pleasant to enjoy, but both can harm health if drinkers consume too much. If there’s one large similarity between both dark and clear alcohol, it’s that they’re best consumed in moderation.

Suzanne Dixon is a registered dietician and oncology writer for the Mesothelioma Center at Suzanne has delivered more than 200 lectures on on cancer, nutrition, epidemiology and public health to academic, professional, patient and consumer audiences. Dixon has more than 20 years experience in nutrition and epidemiology, having previously managed the outpatient oncology nutrition programs at the University of Michigan Health Systems.