Calorie Calculator

This Calorie Calculator is based on several equations, and the results of the calculator are based on an estimated average. The Harris-Benedict Equation was one of the earliest equations used to calculate basal metabolic rate (BMR), which is the amount of energy expended per day at rest. It was revised in 1984 to be more accurate and was used up until 1990, when the Mifflin-St Jeor Equation was introduced. The Mifflin-St Jeor Equation also calculates BMR, and has been shown to be more accurate than the revised Harris-Benedict Equation. The Katch-McArdle Formula is slightly different in that it calculates resting daily energy expenditure (RDEE), which takes lean body mass into account, something that neither the Mifflin-St Jeor nor the Harris-Benedict Equation do. Of these equations, the Mifflin-St Jeor Equation is considered the most accurate equation for calculating BMR with the exception that the Katch-McArdle Formula can be more accurate for people who are leaner and know their body fat percentage.

The value obtained from these equations is the estimated number of calories a person can consume in a day to maintain their body-weight, assuming they remain at rest. This value is multiplied by an activity factor (generally 1.2–1.95) dependent on a person's typical levels of exercise, which accounts for times during the day when a person is not at rest. 1 pound, or approximately 0.45 kg, equates to about 3,500 calories. As such, in order to lose 1 pound per week, it is recommended that 500 calories be shaved off the estimate of calories necessary for weight maintenance per day.

It is important to remember that proper diet and exercise is largely accepted as the best way to lose weight. It is inadvisable to lower calorie intake by more than 1,000 calories per day, as losing more than 2 pounds per week can be unhealthy, and can result in the opposite effect in the near future by reducing metabolism. Losing more than 2 pounds a week will likely involve muscle loss, which in turn lowers BMR, since more muscle mass results in higher BMR. Excessive weight loss can also be due to dehydration, which is unhealthy. Furthermore, particularly when exercising in conjunction with dieting, maintaining a good diet is important, since the body needs to be able to support its metabolic processes and replenish itself.

Calorie Counting as a Means for Weight Loss

Calorie counting with the intent of losing weight, on its simplest levels, can be broken down into a few general steps:

1. Determine your BMR using one of the provided equations. If you know your body fat percentage, the Katch-McArdle Formula might be a more accurate representation of your BMR. Remember that the values attained from these equations are approximations and subtracting exactly 500 calories from your BMR will not necessarily result in exactly 1 pound lost per week.
2. Determine your weight loss goals. Recall that 1 pound (~0.45 kg) equates to approximately 3,500 calories, and reducing daily caloric intake relative to estimated BMR by 500 calories per day will theoretically result in a loss of 1 pound a week. It is generally not advisable to lose more than 2 pounds per week as it can have negative health effects. Consulting your doctor and/or a registered dietician nutritionist (RDN) is recommended in cases where you plan to lose more than 2 pounds per week.
3. Choose a method to track your calories and progress towards your goals. If you have a smartphone, there are many easy-to-use applications that facilitate tracking calories, exercise, and progress. Many have estimates for the calories in many brand-name foods or dishes at restaurants. Manually maintaining a spreadsheet or journal are also viable alternatives.
4. Track your progress over time and make changes to better achieve your goals if necessary. Remember that weight loss alone is not the sole determinant of health and fitness. It is also ideal to take measurements under consistent conditions, such as weighing yourself as soon as you wake up and before breakfast.
5. Keep at it!

In its most basic form, calories consumed minus calories expended will result in weight gain if the result is positive, or weight loss if the result is negative. However, this is far from a comprehensive picture, and many other factors play a role in affecting healthy, sustainable weight loss. Consistent with the view that only net calories are important, there exist cases such as the Twinkie diet, where a person solely counting calories managed to lose 27 pounds over two months — though this is certainly not suggested.

Aside from being one viable method for facilitating weight loss, calorie counting has other advantages including helping to increase nutritional awareness. Many people are completely unaware of, or grossly underestimate their daily caloric intake. Having actual caloric measurements can also assist in weight loss, since tangible calorie goals can be set, rather than simply trying to eat less. Tracking calories also puts exercise in a quantifiable perspective, increasing a person's awareness regarding how much exercise is required to counteract a snack.

Zigzag Calorie Cycling

Zigzag calorie cycling is a weight loss approach that aims to counteract the human body's natural adaptive tendencies. Over a period of time, it is possible for the body to adapt to a lower number of calories consumed, resulting in a weight-loss plateau. Zigzag calorie cycling involves alternating the number of calories consumed on a given day — a combination of high-calorie and low-calorie days that meet the same overall weekly calorie target.

For example, if your target calorie intake is 14,000 calories per week, you could consume 2,300 calories three days a week, and 1,775 the other four days, or you could consume 2,000 calories each day. In both cases, 14,000 calories would be consumed over the week, but the body wouldn't adapt and compensate for a steady 2,000-calorie diet. This also allows a person more flexibility in their diet, allowing them to plan around occasions such as work or family gatherings.

There is no concrete rule or study that dictates the most effective way to alternate calorie consumption. Depending on a person's activity level, it is generally recommended that the high-calorie and low-calorie days vary by approximately 200–300 calories, where the high-calorie day is often the number of calories needed to maintain current weight.

How Many Calories Do You Need?

Some factors that influence the number of calories a person needs to remain healthy include age, weight, height, sex, levels of physical activity, and overall general health. For example, a physically active 25-year-old male that is 6 feet in height requires considerably higher calorie intake than a 5-foot-tall, sedentary 70-year-old woman. Though it differs depending on age and activity level, adult males generally require 2,000–3,000 calories per day to maintain weight while adult females need around 1,600–2,400 according to the U.S. Department of Health.

Harvard Health Publications suggests women get at least 1,200 calories and men get at least 1,500 calories a day unless supervised by doctors. As such, it is highly recommended that a person attempting to lose weight monitors their body's caloric necessities and adjusts them as necessary to maintain its nutritional needs.

Calories: Different Kinds and Their Effects

The main sources of calories in a typical person's diet are carbohydrates, proteins, and fat, with alcohol also being a significant portion of calorie intake for many people. Some studies have shown that the calories displayed on nutrition labels and the calories actually consumed and retained can vary significantly.

Generally, foods that take more effort to chew — fruit, vegetables, lean meats, whole grains, etc. — require the body to burn more calories since more calories are required to digest them. Furthermore, certain foods like coffee, tea, chilies, cinnamon, and ginger have been found to increase the rate of calories burned. There are different classifications of foods in terms of calories: high-calorie foods, low-calorie foods, and empty calories.

While there is no clear-cut or ideal amount of macronutrient proportions a person should consume to maintain a healthy diet or lose weight, eating a "healthy" diet replete with a variety of unprocessed foods such as vegetables, fruits, and lean meats is correlated with being healthier, and is more likely to result in sustainable weight loss. Also, remember that calories from drinks comprise an estimated 21% of a typical person's diet — many of these fall under the category of empty calories.

Remember: All foods, including "healthful foods," should be consumed in moderation, and distinctions can often be misleading since even natural foods like fruits can have large amounts of sugar, and foods labeled as "health foods" can potentially replace one unhealthy component with another.

Calories in Common Foods

2000, 1500, and 1200 Calorie Sample Meal Plans

Calories Burned from Common Exercises (1 hour)

Energy from Common Food Components