You’ve probably heard the weight-loss “rule” that it takes 3,500 calories to lose a pound. The idea is that you can lose one pound by creating a 3,500-calorie deficit — either by burning 3,500 calories or by eating 3,500 fewer calories.
But it’s not that simple. How many calories it takes to lose a pound varies from person to person, and it can change from week to week. Here’s what you need to know about calories — and how many you need to reach your goals.
What Are Calories?
Short answer: Calories are the amount of energy a food or drink provides.
One calorie is the amount of energy it takes to raise the temperature of 1 gram of water by 1 degree Celsius. But the calories we see listed on nutrition labels actually refer to kilocalories — the amount of energy needed to raise the temperature of 1 kilogram of water by 1 degree Celsius.
Historically, researchers used a tool called the bomb calorimeter to determine how many calories a food contained. Now, scientists and manufacturers typically rely on the Atwater system, which calculates the calories in a food based on the calorie values of its macronutrients:
- Carbohydrate = 4 calories per gram (grams of carbohydrates in the form of insoluble fiber may be subtracted from the total number of grams)
- Fat = 9 calories per gram
- Protein = 4 calories per gram
- Alcohol, aka the “fourth macro” = 7 calories per gram
How Many Calories Should You Eat Each Day?
First things first: It’s important to understand why we need calories. We use the energy from food (aka calories) to live and breathe, grow and repair cells, circulate blood, and adjust hormone levels, and for many other processes that hum away even when we’re parked on the couch.
These functions make up our basal metabolic rate (BMR), also called resting metabolism. This is the minimum number of calories you should consume each day; dipping below that number can actually sabotage your weight-loss efforts.
Of course, physical activity — whether we’re talking about mundane tasks like folding laundry or more vigorous endeavors like going for a run — burns additional energy. And genes, hormones, and gut bacteria can also play a role in how your body uses calories, says Sonya Angelone, MS, RDN, and spokesperson for the Academy of Nutrition and Dietetics.
So how many calories do you need each day? There’s no one-size-fits-all answer for this — it depends on your age, your size, how much muscle you have, your activity level, and your weight goals. (You can estimate your daily calorie goal based on these factors using the National Institute of Health’s Body Weight Planner.)
How Many Calories Does It Take to Lose a Pound?
The “3,500 calories to lose a pound” rule is appealing because it sounds simple — if you want to lose a pound per week, just aim for a 500-calorie-per-day deficit. But weight loss is more dynamic than that.
“Weight loss is more than a math equation,” Angelone says. “For most people, 500 calories is a modest reduction and one that is realistic to maintain. However, it doesn’t naturally translate to a one-pound weight loss per week.”
In fact, the 3,500-calorie rule can significantly overestimate the amount of expected weight loss, because it doesn’t account for important factors like the way energy expenditure can decrease as you lose weight. “As those pounds come off, your metabolic rate goes down because there’s less of you,” says Andrea N. Giancoli, MPH, RD, registered dietitian and Openfit nutrition manager.
Another problem with the 3,500-calorie rule: If you approach weight loss as a simple “calories in, calories out” equation, you may be tempted to severely restrict your calorie intake to create a bigger deficit. But that can backfire by slowing down your metabolism, Angelone says: “Then you don’t require as many calories, so weight loss will slow down.” Dietary restriction can also lead to decreased muscle mass, which further hinders your weight-loss efforts.
Rather than trying to calculate how many calories it takes to lose a pound, focus on eating a healthful, balanced diet.
Why What You Eat Matters
A calorie is a calorie, right? Well, not really. While you don’t want to consume more calories than you need, research suggests weight loss isn’t just about the number of calories you eat and burn, but also where those calories come from. Let’s put it this way: Your body will respond differently to 400 calories’ worth of roasted chicken and steamed veggies versus the same calorie allotment of soda and donuts.
“It’s important that we choose quality foods rather than empty calories,” Giancoli says. Otherwise, it’s easy to miss out on important nutrients.
High-quality foods — like whole grains, nuts, lean protein, fruit, vegetables — can help support sustainable weight loss over time. There are plenty of nutritious foods that are naturally low-calorie, like fruits and veggies. Plus, there are smart ways to make healthier swaps for your favorite higher-calorie foods. “Calories should be based on eating a variety of healthy, minimally processed foods,” Angelone says.
The Benefits and Drawbacks of Calorie Counting
For many people, counting calories can be a great starting point — it offers a form of structure, and tracking calories can help you get a handle on what you consume, how much you consume, and when you consume it. But calorie counting takes a lot of effort and time, and it’s not for everybody, Giancoli says.
And the biggest problem with counting calories, Angelone says, is that we tend to focus more on numbers — not how full we are or which foods make us feel good.
Bottom line? The 3,500-calorie myth is just that — a myth. Can a combination of eating less and exercising more help you lose weight? Of course, but there’s no perfect mathematical equation for weight loss. For healthy, sustainable weight loss, focus on cutting out the junk, adding in wholesome foods, and sticking to a fitness routine you enjoy.