Why the 3,500-calorie rule doesn't always work
"A well-known piece of diet advice is the 3,500-calorie rule: If you decrease your intake by 500 calories a day or 3,500 calories a week, you will lose one pound a week. This is based on the fact that a pound of fat stores about 3,500 kilocalories (or calories)," explains registered dietitian Cindy Solis, Gundersen Nutrition Therapy.
Cindy Solis, RD, Gundersen Nutrition Therapy
But she's quick to add this rule doesn't work well. Here's why:
First, you would have to cut back an average of 500 calories per day from the calories your body needs for weight maintenance. "If you have been gaining weight, eliminating 500 calories per day will not result in a one-pound weekly loss. More likely, you will see a less-significant weight loss, keep your weight stable or slow down the rate at which you are gaining weight," says Cindy.
Secondly, the rule requires calorie counting and people tend to underestimate how many calories they are consuming—by 600 calories or more a day, according to research. Similarly, people tend to overestimate the calories they burn when exercising.
Even for the most compliant and diligent calorie tracker, the rule still does not hold up long term. According to Cindy, "Your body weight and your composition affect your metabolism. Body composition—the percentages of fat, bone, water and muscle—generally changes as your weight decreases. The 3,500-calorie rule does not account for this."
So what you can do?
Cindy says, "Stay active and be consistent. A balanced diet along with regular exercise will prevent unfavorable changes in your body composition as you lose weight."
"Exercising to purge calories is not very effective for weight loss," she points out. "Consistent daily physical activity helps to maintain or build muscle and rev up your metabolism."
While calorie tracking may help build awareness, Cindy says that for most people it's not accurate or useful long term. Instead, listen to your body. Respect your physical hunger, fueling your body with nourishing foods and stop eating when you are full. Choose nutritious, balanced options most of the time and allow for occasional treats.
Finally, focus on the process and take time to celebrate the little successes. Don't fixate on the scale; instead think about the positive healthy changes as you lose weight. Do you have more energy? Are you sleeping better? Are there improvements in your blood pressure, blood sugar or other health issues? Are you back living your life? These are the things worth celebrating.