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THOUGH LOSING WEIGHT feels complicated, the math on it is pretty simple.

Ultimately, weight loss comes down to one thing: a calorie deficit. This is defined as calories put in verses calories put out. When you eat more calories than you use, those spare calories get stored to use for later. This ends up as our fat tissue. When we use more calories than we eat, we utilize those fat stores to provide the extra calories we need to perform our daily tasks.

The only certain way to lose weight, then, is to put out more calories than you consume. This is called a calorie deficit.

Simple, right? By no means are we saying that losing weight is easy—there are many factors that may hinder weight loss, like hormone troubles and other medical conditions. But, when it comes down to the science, it's not as complicated as fad diets market it to be. Weight loss will not happen without a calorie deficit. All you need is a little math to figure out your numbers.

Make no mistake, though: Counting calories and putting yourself into a calorie deficit does not mean you have to micromanage the way that you eat. There are easy calculations designed to help you start dropping pounds in a safe and effective way—without hassle, and without stress.

Here's the best way to determine calorie intake, which is your first step to maintaining a calorie deficit, which is your first step to finally stepping onto the scale and seeing the number you want.

What Is a Calorie Deficit?

Really, weight loss is like accounting, but with the exact opposite goal: You want to end up in the red, burning more calories than you consume. Although calories have been knocked around in recent years, they are still a dependable guide to help you establish a daily intake goal when it comes to healthful food.

As Dana Ellis Hunnes Ph.D., M.P.H., R.D., a senior clinical dietitian at UCLA medical center and author of Recipe For Survival, explains, a calorie deficit occurs when you expand more calories from activity and daily living than you take in from the foods and beverages that we consume.

“There is more than one way to achieve a calorie deficit," Ellis Hunnes says. "One way would be to consume fewer calories than you expend, and a second way would be to burn more calories than you take in. A third way would be a combination of the two where you take in fewer calories and burn more calories than you consume overall.”

You don't want to aim for a maximal calorie deficit. If you cut too many calories, you'll end up breaking down muscle stores rather than fat stores.

What Are the Benefits of Maintaining a Calorie Deficit?

There are physical benefits and mental benefits.

You’ll Lose Weight

Ellis Hunnes highlights that one benefit to maintaining a calorie deficit, “as long as it is not too big of a deficit that you’re constantly in starvation mode and feeling hungry,” is that weight loss will naturally ensue. “However, one must be careful that they do not reduce their caloric intake too much so that they do not lose muscle mass.” The National Institutes of Health deems a healthy weight loss one where you lose about 10 percent of starting weight over six months. That equates out to about 1/2 to 3/4 of a pound a week.

You May Decrease Inflammation

Chronic inflammation is behind everything from heart disease to erectile dysfunction.

“A benefit to maintaining a calorie deficit is it decreases inflammation and the expression of IGF-1,” says Ellis Hunnes. “Since many chronic conditions are exacerbated by inflammation, having a calorie deficit can lower inflammation and therefore lower the risk of developing a chronic condition,” she says, adding that this research again has been shown in animal studies and even in certain human studies.

You May Live Longer (Maybe)

The verdict may still be out, but this potential for enhanced lifespan is certainly exciting. “A benefit to maintaining a calorie deficit is a potential increase in longevity. Studies in monkeys and mice indicate that a calorie deficit of around 80 percent of calorie needs extends the life of the animal,” says Ellis Hunnes. “While this has yet to fully pan out in humans, the research is there in animal studies.”

You Won't Have to Exclude Foods

When you maintain a calorie deficit, you no longer have to make any food—or food groups—off-limits. That means that you don’t have to restrict what you eat, even if you may have to cut back on how much of it you enjoy.

How Much of a Calorie Deficit You Need?

To lose one pound of fat, you need to be in a deficit of 3,500 calories.

By no means does that mean you need to be in a deficit of 3,500 calories every day. The rate at which you lose weight is dependent on several things, like how much weight you have to lose, and how timely it is that you lose it. If you need to cut a lot of weight quickly to better your health, than you’ll need to be in a higher calorie deficit. For example, if your weight is putting you at high risk for something like a heart attack, you might need to cut weight fast.

In general, though, it’s regarded to be safe to lose a half to one pound a week. That’s a deficit of 250 to 500 calories a day. For reference, 250 to 500 calories is about one to two servings of pasta, or one to two six-ounce chicken breasts.

Talk to a doctor about the how much and how quickly you should cut weight. Knowing this information will help you better calculate how much you should cut out each day.

How to Calculate a Calorie Deficit

Here's your two-step plan.

Step 1: Figure Out Daily Calorie Intake

The first best place to start is with how many calories you’re currently eating.

Track everything you eat and drink for three days (just one day might not give you the most accurate assessment) and tally your daily total at FitDay.com or with an app like Lose It!, MyFitnessPal, or MyPlate. Don't worry, this is easier than it sounds.

Next, estimate the number of calories you need to maintain your weight using the formula below based on your activity level—specifically, how often you work out.

(Note: These following sample calculations are for a 185-pound person.)

A. Zero workouts

Multiply your weight by 10. At 185 pounds, that's 1,850 calories a day. This is your basal metabolic rate.

B. One or two workouts a week

Your weight x 12 (2,220 calories)

C. Two to four workouts a week

Your weight x 14 (2,590 calories)

D. Five or more workouts a week

Your weight x 16 (2,960 calories)

Now compare those two numbers—the number of calories you currently eat vs. the number of calories you need to eat to maintain your weight. How far off are you? If you’re eating more than your target number, you’ll gain weight; if you eat less, you’ll lose weight.

Step 2: Calculate Daily Calories Burned

If you’re not already in a caloric deficit, first aim for a maximum daily deficit of 250 to 500 calories when you're trying to shed some pounds. (Again, healthy and sustainable weight loss is one half to one pound a week.) That means either eating fewer calories or burning more calories throughout your day.

So if our 185-pound man works out 2 to 4 days a week, eating 2,590 calories a day maintains his weight. Here's how his body uses those calories and a few ways he can burn more calories.

1. Basal Metabolic Rate (BMR): 60 to 75 percent of daily calories burned

This is how much energy your body uses just to stay alive. You can get a rough estimate of this number with an online BMR calculator that takes into account your height, weight, gender and age.

70 percent = 1,813 calories

2. Thermic Effect of Food: 10 percent

These are the calories burned by digestion. In general, you burn 0 to 3 percent of the calories of fat you eat, 5 to 10 percent for carbohydrates, 20 to 30 percent for protein, and 10 to 30 percent for alcohol.

10 percent = 259 calories

Because you use far more of the calories from protein for digestion than you do with fat or carbs, make sure you reach your target amount of daily protein. That way, you can burn more sans a ton of effort. For adult men, that means at least 56 grams of protein a day. Opt for a lean protein source like chicken or fish.

3. Physical Activity: 15 to 30 percent

Weight Loss After 40

Weight Loss After 40

These are the calories you expend through your daily activity level, including exercise and any other movement. If you wear a fitness tracker, you can get a pretty good estimate of how many calories you’re burning each day based on steps or heart rate. Or you can enter individual activities and workouts into an online exercise calculator.

20 percent = 518 calories

Also important: Don't forget about liquid calories—and we're not just talking soda here!

It's easy to forget about that morning juice or two glasses of wine with dinner. That's why it's important to keep track of your beverage intake too. Liquids can easily add up and make you consume more calories than you think.

For example, one can of beer contains roughly 153 calories, depending on the brand. Drinking just two adds an additional 300 calories per day, which can be significant if you're only cutting back by 250 to 500 calories daily.

How to Achieve A Calorie Deficit:

Creating a calorie deficit sounds simple: burn more calories than you take in. But nothing is ever as easy as it sounds, is it?

The most important thing when trying to achieve a calorie deficit is by figuring out how many calories you’re intaking on a daily basis. This isn’t as easy as it sounds— it can be tedious to have to measure out all of your food and add up all the nutrition facts.

Luckily, there are tools to make it a little bit easier. There are several apps available that make tracking your calories easily, like MyFitnessPal and LoseIt. These apps have databases of thousands of foods and their caloric content. Log how much you had, and it will do all the calculations for you.

If tracking just doesn’t feel like it’s for you, there’s plenty of other things you can do to cut your calories. Simple habits like cutting snacks, or swapping your side of fries for a salad are both easy ways to cut calories without stressing too much. If you’re looking for more easy ways, we got you.

The key is to focus on what you're taking in. Studies suggest your body takes in more calories from processed food that's been broken down from its natural form. So if you have a smoothie, you'll absorb more calories than if you ate the same fruits in that shake raw. And foods in their whole form tend to be more satiating, which may help you eat less overall.

Run this calorie deficit long-term, while also focusing on eating a wide and rich diet of nutrient-dense, whole foods and you'll lose weight, sure, but you'll also gain so much more.

Why Am I Not Losing Weight on A Calorie Deficit?

If your diet is still rich in junk food—you're not eating a diet that sets you up for long-term health. You also might be consuming a ton of salt which will cause you to bloat and hold onto water weight for a few days, so you may see the scale bump up for a little bit after a salt-heavy meal. Those effects won't last, but it's still important to keep a diet that includes a variety of lean proteins (including heart-healthy, omega-3-fatty-acid-rich fish), lots of fruits and vegetables, and plenty of fiber.

You may also have some kind of underlying condition that make it difficult to lose weight, such as a thyroid problem, diabetes, or congestive heart failure. If you feel like you've done all you can and you're still not seeing results, it might be time to see a doctor.

If you still find yourself struggling, it’s always a good idea to get in touch with a registered dietician. Together you can come up with a game plan to ensure you stay in a calorie deficit.