How Many Calories Should a 19-Year-Old Eat a Day?

How many calories a 19-year-old should eat daily depends on size, goals, activity level and gender. Active males looking to build muscle need a lot more calories than petite women who are primarily sedentary. If you can't meet with a dietitian to figure out your personal needs, use an equation that factors in your weight, height and goals on an online calorie counter. Any caloric calculation is simply a guideline from which to establish a healthy eating pattern for life.

Average calorie needs for a 19-year-old give you an idea of what you should consume, but not everyone fits the "average" mold. The USDA Dietary Guidelines for Americans define the average male as 5 feet, 10 inches, weighing 154 pounds and the average woman as 5 feet, 4 inches tall, weighing 126 pounds.

If you're close to this size and sedentary, you need about 2,400 to 2,600 calories as a man and 1,800 to 2,000 calories as a woman. For those who are moderately active, a man needs 2,600 to 2,800 calories and a woman 2,000 to 2,200 calories. For the "active" 19-year-old, 3,000 calories a day is appropriate for a man and 2,400 calories for a woman. The USDA defines moderately active as walking a 3- to 4-mph pace for 1.5 to 3 miles daily and active as walking 3 miles or more per day at 3 to 4 mph.

If you play college sports or are larger, or smaller, than the "average" statistics, the USDA estimates aren't accurate. A formula can help you calculate your individual needs. The Harris-Benedict is the most widely used equation to help figure out daily resting metabolic rate, also called basal metabolic rate, or BMR. This is the number of calories you need to simply survive, apart from any daily activity or exercise.

To use the formulas, you'll need to convert your weight into kilograms and height into centimeters. Simply divide the number of pounds by 2.2 to get kilograms. To convert your height, multiply the number of inches tall you are by 2.54 to get your height in centimeters.

For a man: BMR = (88.4 + 13.4 x weight in kilograms) + (4.8 x height in centimeters) – (5.68 x age)

So, if you're a 6-foot tall, 180-pound male, according to this equation, you need 1,954 calories if all you do is lie in bed all day.

For a woman: BMR = (447.6 + 9.25 x weight in kilograms) + (3.1 x height in centimeters) – (4.33 x age)

If you're a woman who's 5 feet, 6 inches and weighs 140 pounds, your resting metabolic rate comes out to 1,474 calories.

To figure in your activity level, multiply your results by 1.2 if you're sedentary; by 1.375 if you do light exercise one to three times per week; by 1.55 if you participate in sports or exercise three to five times per week; by 1.725 if you do hard exercise or sports practice six to seven days per week; or by 1.9 if you're extremely active and do physical labor and sports training every day.

If you'd rather not do the math, find an online calorie calculator; plug in your information and let it calculate your daily calorie needs for you.

For the examples above, a 19-year-old, 6-foot, 180-pound male who has college basketball practice six times per week needs about 3,370 calories daily, while the 19-year-old, 5-foot, 6-inch girl who goes to the gym just twice per week needs about 2,026 daily calories.

Once you figure out a basic calorie intake to maintain your weight, tweak it to fit your personal goals.

To lose weight, create a 500- to 1,000-calorie deficit. For many people, creating this deficit by trimming calories alone isn't possible. You should not eat fewer than 1,200 calories per day if you're a woman or 1,800 calories per day if you're a man -- or risk nutritional deficiencies, a stalled metabolism and muscle loss. So, to create the deficit, you may need to move more as well as eat slightly fewer calories; if that's not possible, settle for a slower rate of loss.

If you're a 19-year-old looking to put on weight or muscle, create a calorie surplus. A healthy rate of gain is about 1/2 to 1 pound per week, so you need to consume 250 to 500 calories extra per day. Gain this weight mostly in the form of muscle by accompanying your calorie increase with a greater protein intake and weight-training at the gym.

Counting calories isn't your only option when it comes to healthy eating. Instead of worrying so much about the numbers, consider what you're eating every day. Choose mostly whole, unprocessed foods such as vegetables, fruits, lean proteins, whole grains and unsaturated fats, such as those found in avocados, nuts and salmon.

At 19, you're still building bone density and growing muscle. Severe calorie or nutrient deprivation can affect this process. You want to get adequate calcium from three or more servings of low-fat dairy daily, or alternatives such as tofu or canned fish with bones.

Keep sugary and fried foods to a minimum to prevent undue weight gain. Drink water instead of sugar-sweetened beverages. Even if you're at a satisfactory body weight, excess sugar and unhealthy fats can cause health problems.