Your weight is a balancing act, and calories play a big role. Find out how calories determine your weight and ways you can best cut calories from your diet.
Despite all the diet strategies out there, weight management still comes down to the calories you take in versus those you burn off.
Fad diets may promise you that avoiding carbs or eating a mountain of grapefruit is the secret to weight loss, but it really comes down to eating fewer calories if you want to shed pounds.
Calories: Fuel for your body
Calories are the energy in food. Your body has a constant demand for energy and uses the calories from food to keep functioning. Energy from calories fuels your every action, from fidgeting to marathon running.
Carbohydrates, fats and proteins are the types of nutrients that contain calories and are the main energy sources for your body. Regardless of where they come from, the calories you eat are either converted to physical energy or stored within your body as fat.
These stored calories will remain in your body as fat unless you use them up, either by reducing calorie intake so that your body must draw on reserves for energy, or by increasing physical activity so that you burn more calories.
Tipping the scale
Your weight is a balancing act, but the equation is simple: If you eat more calories than you burn, you gain weight.
Because 3,500 calories equals about 1 pound (0.45 kilogram) of fat, you need to burn 3,500 calories more than you take in to lose 1 pound.
So, in general, if you cut 500 calories from your typical diet each day, you'd lose about 1 pound a week (500 calories x 7 days = 3,500 calories).
It isn't quite this simple, however, and you usually lose a combination of fat, lean tissue and water. Also, because of changes that occur in the body as a result of weight loss, you may need to decrease calories further to continue weight loss.
Cutting calories doesn't have to be difficult. In fact, it can be as simple as:
- Skipping high-calorie, low-nutrition items
- Swapping high-calorie foods for lower calorie options
- Reducing portion sizes
Saving calories by cutting high-calorie, low-nutrition items
Skipping one or two high-calorie items is a good place to start when cutting calories. For example, you could skip your morning latte, soda at lunch or that bowl of ice cream you always have after dinner.
Think about what you eat and drink each day and identify items you could cut out. If you think that skipping your indulgence will leave you with a craving, try a low-calorie substitution.
Swapping high-calorie foods for lower calorie options
Simple substitutions can make a big difference when it comes to cutting calories. For example, you can save 60 calories a glass by drinking fat-free milk instead of whole milk. Instead of having a second slice of pizza, reach for some fresh fruit. Or snack on air-popped popcorn instead of chips.
Reducing your portion sizes
The sizes of your portions affect how many calories you're getting. Twice the amount of food means twice the number of calories.
It's common to underestimate how much you're eating, especially if you're dining out. Controlling your portions is a good way to control calories.
Try these tips to control portion sizes and cut calories:
- Start small. At the beginning of a meal, take slightly less than what you think you'll eat. You can have seconds later if you're truly still hungry.
- Eat from plates, not packages. Eating directly from a container gives you no sense of how much you're eating. Seeing food on a plate or in a bowl keeps you aware of how much you're eating. Consider using a smaller plate or bowl.
- Check food labels. Be sure to check the Nutrition Facts panel for the serving size and number of calories per serving. You may find that the small bag of chips you eat with lunch every day, for example, is two servings, not one, which means twice the calories you thought.
- Use a calorie counter. Check out reputable resources that offer tools to count calories, such as websites or smartphone applications. One to try is the SuperTracker at ChooseMyPlate.
Putting it all together
Replacing high-calorie foods with lower calorie alternatives and reducing your portion sizes can help you cut calories and improve weight control. For a successful — and sustainable — weight management plan, you also need to increase your physical activity. Combining regular activity and healthy eating will best help you achieve and maintain a healthy weight.
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How Many Calories Are in a Pound of Body Fat?
Calories are the energy in food.
They fuel everything you do, from sleeping to running a marathon.
Calories can come from carbs, fat and protein.
Your body can use them to fuel work right away, or store them for later use.
Some calories can be stored as glycogen (carbs), but the majority is stored as body fat.
This article explains how many calories are in a pound of body fat.
It also discusses the 500-calorie deficit myth and presents some tools for predicting realistic weight loss.
What Is Body Fat?
Let's take a moment to define what we mean by body fat.
For starters, body fat is not just pure fat.
Pure fat has a very high energy content, or about 9 calories per gram. This amounts to about 4,100 calories per pound of pure fat.
However, body fat is not just pure fat. Body fat consists of fat cells, called adipocytes, which also contain some fluids and proteins in addition to fat.
Therefore, the calorie content of body fat is going to be a bit less than the calorie content of pure fat.
Body fat is mixed with fluid and protein. Therefore, its composition and calorie content is not the same as pure fat.
Does One Pound of Body Fat Contain 3,500 Calories?
In 1958, a scientist named Max Wishnofsky concluded that the caloric equivalent of one pound of body weight lost or gained was 3,500 calories (3).
He based his conclusion on the scientific evidence available at the time. Decades later, his result has been cited thousands of times in the media and scientific literature (4, 5, 6, 7).
It's basically become common knowledge that one pound of body fat contains 3,500 calories. But is it really true? Let's attempt to find out.
We will be using generally accepted values for this calculation. However, some research does show slight variations.
In general, we can assume that:
- One pound equals 454 grams.
- Pure fat contains 8.7–9.5 calories per gram.
- Body fat tissue is 87% fat.
Using those values, we can conclude that a pound of body fat actually contains anywhere from 3,436 to 3,752 calories.
However, it is important to note that these calculations are based on old research.
Some of the studies state that body fat tissue contains only 72% fat. Different types of body fat may also contain varying amounts of fat.
A pound of body fat may contain anywhere between 3,436 and 3,752 calories, roughly estimated.
The 500-Calorie Deficit Myth
It is a common myth that if you eat 500 fewer calories each day, or 3,500 fewer calories a week, you will lose one pound of fat each week.
This would equal a total of 52 pounds in a year.
However, the reality is very different.
The 500-calorie deficit myth significantly overestimates the potential weight loss that can be achieved over a period of time.
This estimate seems to work fairly well in the short term, for moderate weight loss in overweight and obese people. But it falls apart in the long term, and sets people up for failure and disappointment.
What this myth fails to account for is the body's response to the changes in body composition and diet.
When you reduce calorie intake, your body responds by making you burn fewer calories. You start moving around less, and the body becomes more efficient. It does the same amount of work, but uses fewer calories than before.
You may also lose muscle mass along with the fat, which also makes you burn fewer calories.
This is often called starvation mode, although the technical term is "adaptive thermogenesis".
Weight loss is not a linear process, and typically slows down over time.
The 500-calorie deficit diet overestimates the potential for weight loss. It does not account for changes in body composition and a reduction in calories burned.
Better Tools for Predicting Weight Loss
Nowadays, there are apps and online tools that may provide a better, more realistic assessment of your predicted weight loss.
The Body Weight Planner, developed by the National Institute of Health, provides calorie levels for both weight loss and maintenance.
It takes into account how diet and exercise contribute to weight loss, as well as how your body responds to reduced calorie intake. It has an immense amount of mathematical calculations behind it.
Another good tool to predict weight loss is the Single Subject Weight Change Predictor, developed by the Pennington Biomedical Research Center.
This tool also allows you to calculate weight loss, based on dietary intake and exercise.
The 500-calorie deficit rule is not a realistic way to predict weight loss. Better tools exist to predict weight loss over a period of time.
Weight Loss Isn't Just Fat Loss
When you're trying to lose weight, what you really want to get rid of is body fat — both under the skin and around the organs.
Unfortunately, weight loss doesn't necessarily equal fat loss. One unwelcome side effect of losing weight is the loss of muscle mass.
The good news is that there are some ways to minimize the loss of muscle mass.
- Lift weights: Studies show that resistance training can be incredibly helpful in preventing the loss of muscle mass when losing weight .
- Eat plenty of protein: With a high protein intake, your body is much less likely to break down your muscles for energy.
Both of these strategies are also useful to prevent a reduction in calories burned as you lose weight.
Weight lifting and high protein intake may help prevent muscle loss for people who are trying to lose weight. They can also help prevent a reduction in the amount of calories you burn.
Take Home Message
A pound of body fat may contain anywhere from 3,436 to 3,752 calories.
However, it is a myth that just eating 500 fewer calories per day (3,500 per week) causes weight loss of one pound.
This may work in the short-term, but the body will soon adapt by making you burn fewer calories. For this reason, weight loss slows down over time.
Do You Really Lose a Pound of Fat for Every 3,500 Calories You Burn?
When it comes to weight loss, math can't solve every problem.
Years ago, scientists played around with a pound of squishy, slimy human fat and found that it contained 3,500 calories of energy.
But—sorry to break it to you—burning a pound of fat isn't as simple as burning through 3,500 calories.
Consider the following and infuriating (at least for thin guys) scenario: Two men go on an exercise and eating plan so that they consume 3,500 fewer calories per week than they burn. One man has five pounds to lose; the other has 50. At the end of one week, the leaner guy might lose about half a pound—and a third of the weight will be from muscle. Meanwhile, the obese guy will have lost more than three pounds, mostly from fat and water.
"There's tremendous variability in how a 3,500 caloric deficit affects different people," says Pamela Peeke, M.D., M.P.H., senior science adviser at Elements Behavioral Health and author of The Hunger Fix.
Why's that? Well, one huge factor determining the results of our dieters is body composition. "The more fat a person has to give, the quicker he will lose weight and weight from fat," Peeke explains. Meanwhile, when you get closer to your body weight, your body holds on to fat stores for dear life and sacrifices muscle over fat, she says. The body is perpetually afraid that it will starve; it's perhaps biology's least-sexy-ever survival mechanism.
Meanwhile, how you try to hit your caloric deficit (which is a necessity to lose weight) has a huge impact on whether you lose weight from muscle, fat, or just water.
The faster you try to achieve a deficit, the more weight you will lose from muscle as opposed to fat. As will be the case if you diet alone, she says. However, exercise—and most markedly, strength training—and protein consumption promote muscle growth so that you will not lose as much muscle. In fact, if you consume an adequate amount of protein (the Academy of Nutrition and Dietetics recommends getting 20 to 30 grams, four times a day and after exercise), you could potentially increase your lean-muscle mass while reducing your body-fat percentage.
What's more, if you are cutting calories from carbs, you will also lose water weight. In the body, every gram of glycogen (carbohydrates) in your body is stored with a few grams of water. So when you go low-carb, your metabolism breaks down those glycogen reserves for energy, and you end up peeing out the accompanying water.
That's another reason why, calorie per calorie, obese people tend to drop weight drastically: They have a lot of water to lose.
You also need to realize that your calorie-cutting strategy does alter your metabolism—and what it takes to take in fewer calories than you're consuming over the long haul. Contrary to popular opinion, people's metabolic rates slightly decrease as they lose weight. That's because it takes more energy (a.k.a. calories) to fuel a 280-pound human than a 180-pound one, she says. And if you lose most of your weight from muscle, your metabolism will plummet—which is one more reason why extreme diets suck.
Now that all that's settled, if you want to determine roughly how many calories your body burns a day, check out the Mayo Clinic's calorie calculator. Aim to take in 300 to 500 fewer calories per day to lose weight.