How many calories are there in a cup of tea
Tea without adding anything, has slight, but not zero calories. Cup of brewed black tea (200-250 ml) has about 2 calories (according to the USDA Nutrient Database), which is almost nothing compared to the Recommended Daily Intake of 2000 calories for an adult. The calories come mostly from trace amounts of carbohydrates in the tea leaf. The same is true for most herbal teas.
Sugar adds empty calories
A typical teaspoon of refined (white) sugar amounts to about 4 grams of sugar, which has 15 calories. A typical sugar packet, like those served with tea or coffee in some restaurants, has about 3 grams, or 11 calories. These calories are empty, meaning that they impart no other nutritional value: no vitamins, minerals, or protein.
Milk adds calories and nutrients
Milk or cream can contribute to the calories in tea, but the total amount contributed is usually small relative to the dairy products people consume in food. These calories come from both sugars (like lactose, naturally occurring in dairy products) and fat in milk. 2 spoons of whole milk (a lot more than most people put in their tea) has only 18 calories, 9 of which are from fat. Even adding cream, using the typical amount people add to their tea is unlikely to contribute largely to calories.
Unlike sugar, milk also adds significant nutritional value. Milk contains protein, about 3,5 grams per 100 grams, and some vitamin A, and also is a good source of calcium. In many countries, milk is also fortified with Vitamin D. Vitamins A and D are both fat-soluble vitamins, so they are not well-absorbed from skim milk.
Teas that taste better without sugar or milk
If you feel the desire or need to sweeten your tea, you may wish to consider looking at naturally sweet teas. If you are only used to drinking black tea, you may wish to consider exploring green, white, or oolong teas, many of which can have naturally sweeter, smoother, and less bitter flavors.
Many of the strong black breakfast teas that dominate the tea-drinking cultures in Western countries have been selected for their ability to pair well with milk, cream, or sugar. Asian cultures generally drink their tea pure and unsweetened, and the teas from this culture may taste better to you in this format.