Excess body weight is a widespread problem in the United States, since roughly 7 in 10 adults are either overweight or obese. These statistics, along with the modern lifestyle and all it typically entails -- sitting for hours a day, high stress levels, lack of sleep and poor dietary habits -- might make it seem as if weight gain is inevitable. Understanding the nuances of calorie balance, however, including how many calories you need, how many excess calories it takes to gain a pound of fat, and how many calories you must burn or cut from your diet to lose weight, can help you maintain a trim waistline.
Calories measure the amount of energy supplied by foods and beverages. Your body uses a certain amount of calories to breathe, regulate temperature, contract muscles and otherwise maintain normal function. The rate at which you burn these calories, known as your basal metabolic rate, is relative to your age, gender, weight, height and body composition, and it accounts for 60 to 75 percent of your total calorie needs. Your overall activity level also helps determine the total number of calories you require to maintain your body weight. Consistently taking in more calories than you use each day is a major factor in excess fat accumulation. The energy stored in 1 pound of body fat amounts to 3,500 calories.
How Extra Calories Add Up
When it comes to extra calories, small amounts really can add up. A study published in Lancet in 2011 found that weight gain is usually the result of a small, persistent energy imbalance of just 7 calories a day. Having an extra pat of butter every now and then, splurging on a larger latte or eating a few pieces of candy at the office are examples of how this can happen. Small changes in your daily eating patterns have an even greater impact. If you began drinking a 150-calorie beverage with your lunch every day, for example, you’d boost your weekly caloric intake by 1,050 calories. If you didn’t increase your physical activity or cut calories from elsewhere in your diet, this one drink lead to a 16-pound gain in a year.
Creating a Calorie Deficit
To lose a pound of fat, you must create a calorie deficit, also known as a negative calorie balance. Although you can do this through diet alone, regular exercise enhances the negative balance and greatly increases your chance for long-term success. Losing 1 to 2 pounds a week is considered safe and effective, because losing weight at a faster rate can be harmful and harder to maintain. To lose 1 pound a week, you need to create a calorie deficit of 3,500 calories per week, or 500 calories a day. To burn 2 pounds of fat per week, you must create a weekly calorie deficit of 7,000 calories, or a daily deficit of 1,000 calories.
Just as small amounts of excess calories add up, smaller calorie deficits can also have an impact over time. Dropping a 100-calorie snack from your daily diet can lead to a 10-pound weight loss over the course of a year.
Long-Term Calorie Deficit
Aiming to burn a pound of fat by creating a 3,500-calorie deficit works efficiently for a time, but the rate of weight loss usually slows as pounds drop off, even when the same calorie deficit remains. According to the American Council on Exercise, this phenomenon can be attributed to the changes in metabolism that come from weight loss. These changes mean that someone who follows a calorie-deficit plan that results in a 10-pound weight loss over the course of a year will continue to lose weight at a significantly slower rate -- about 5 pounds a year -- by maintaining the same calorie deficit. You can still boost your body’s weight loss rate, however, by increasing your level of physical activity.
- Centers for Disease Control and Prevention: Obesity and Overweight Statistics
- Centers for Disease Control and Prevention: Finding a Balance
- American Council on Exercise: Fundamentals of Nutrition and Weight Management
- American Council on Exercise: Trimming Off the Fat
- American Council on Exercise: Fitness Professionals and the Fight Against Obesity
- Lancet: Quantification of the Effect of Energy Imbalance on Bodyweight