Summer would not be summer without liberal glasses of cold drinks.

It is essential to keep the body well hydrated to replace water lost in sweat and guard against heat stroke.

But many people tend to forget that everything we drink, just like everything we eat, has nutritional consequences. So, while summer is still young, we'll look at the myriad possibilities to pour over those tinkling ice cubes.

First, of course, there's water, the only essential that is also absolutely calorie-free. Water is delicious on it own but, for variety, a dedicated weight-watcher could add a twist of lemon or lime or a squeeze of orange.

The calories in tea and coffee are so few as to be for all practical purposes nonexistent. They can be kept that way by adding flavorings like cinnamon or cloves, a dash of almond or brandy flavoring extract, or a twist of lemon orange or lime. From there on, however, whatever beverage you choose will add calories.

For example, an eight-ounce glass of ginger ale supplies about 80 calories; root beer about 90; colas 105. As regards MODERATE use of alcohol, there are good things to be said, particularly for wine and beer, which offer a few nutrients as well as calories. One drink before dinner has long been recognized as a tension-reliever and an appetite stimulant. A glass of wine before bedtime is a good soporific for an elderly person who has trouble sleeping. There is evidence that moderate drinkers may have less statistical risk of heart attack than either heavy drinkers or total abstainers.

Of course, alcohol is packed with calories, all of them empty calories. And there's the added fact that mixers, if they're anything but water or club soda, provide extra calories of their own. Thus, depending on how much you pour and the mixer you use, a simple highball can run anywhere from 110 calories to 275. For example:

BEVERAGE CALORIES

Ale, 1 glass - 155

Beer, 1 glass - 110

Rum, 1 1/2-oz. jigger - 150

Whiskey, 1 1/2 oz. - 110

Gin, 1 1/2 oz. - 125

Wine dry, 20 percent alcohol, 4 oz. - 160 light dry, 12 percent, 4 oz. - 100 sweet, 20 percent, 4 oz. - 180

Tonic (quinine water), 8 oz. - 88

Bitter lemon or orange, 8 oz. - 125

The problem is that most of us cannot take in too many empty calories without either cutting back on the good foods that supply essential nutrients or gaining weight. For example, take an average, desk-bound non-active American male, about 35 years old, weighing about 170 pounds. To maintain that weight, he needs about 2,800 calories a day.

Suppose he has two 1 1/2-jigger scotches before dinner (on top of the one before lunch). At 110 calories each, that leaves him 2,470 calories. Then assume he's eating an average American diet, which means he's consuming about 600 calories a day in sugar. All those empty calories add up to 930, leaving 1,870 into which to cram all the nutritious food he needs to maintain health.

That's not an impossible task, but it requires some care.

There are, of course, a number of beverages we would like to recommend over all others. These are listed in the following table and, as you see, offer many essential nutrients that make them desirable components of a good diet year round.