Burning body fat requires creating a calorie deficit, which means burning more calories than you consume. To lose 1 pound of fat, you need to burn approximately 3,500 calories. This is because 1 pound of fat contains about 3,500 calories of stored energy. So to lose 1 pound of fat per week, you need to burn 500 calories more per day than you eat (3,500 calories divided by 7 days = 500 calorie daily deficit).
How many calories are in 1lb of fat?
Fat tissue contains about 3,500 calories per pound. This number is an estimate and can vary slightly depending on factors like gender, age, and body composition. But 3,500 calories per pound is a commonly accepted average. So if you create a 3,500 calorie deficit through diet, exercise or both, you will lose approximately 1 pound of body fat. Keep in mind that you also lose water weight when burning fat, so the number on the scale may decrease slightly faster than just pure fat loss.
Basal Metabolic Rate (BMR)
Your basal metabolic rate (BMR) is the number of calories your body burns at rest to maintain basic bodily functions like breathing, blood circulation, cell production, nutrient absorption, brain function, hormone regulation, etc. It does not include calories burned through physical activity. BMR makes up the largest portion, 60-75%, of your total daily calorie expenditure. BMR is influenced by factors like:
- Age – BMR decreases as you get older
- Sex – Men tend to have a higher BMR than women
- Body size & composition – More muscle mass increases BMR
- Genetics – Some people inherit a naturally faster or slower metabolism
The average sedentary adult has a BMR of about 1,200-1,500 calories per day. You can calculate your approximate BMR using an online calculator.
Calories Burned Through Activity
In addition to your BMR, you burn calories through physical activity and exercise. The more active you are, the higher your total daily calorie expenditure will be. Here are estimates for how many calories common activities burn per hour for a 125 lb (57 kg) person:
| Activity | Calories Burned Per Hour |
|---|---|
| Walking (2 mph) | 185 |
| Light jogging (5 mph) | 355 |
| Cycling (10 mph) | 260 |
| Swimming laps | 365 |
| Weightlifting | 220 |
| High intensity interval training | 445 |
The exact amount of calories burned during physical activity depends on your weight, intensity level, conditioning, genetics and other factors. Heavier people burn more calories for the same exercise duration. High intensity burns more calories per minute than low intensity. And as your cardio fitness improves, your calorie burn becomes more efficient.
Daily Calorie Deficit Needed to Lose 1lb per Week
Now that you know how many calories are in a pound of fat and what influences calorie expenditure, you can estimate the deficit needed to lose 1 pound weekly:
- There are 3,500 calories in 1 lb of fat
- To lose 1 lb of fat per week, you need a 3,500 weekly calorie deficit
- Divided over 7 days per week, that equals a 500 daily calorie deficit
So in simple terms, burning about 500 more calories than you eat every day should result in an average fat loss of 1 pound per week. This calorie deficit can be created through:
- Consuming 500 fewer calories per day
- Burning 500 extra calories per day through exercise
- A combination of diet and exercise
Creating a 500 Calorie Deficit Through Diet
To lose weight through diet alone, you need to reduce your food intake by about 500 calories daily. This could involve:
- Skipping high calorie beverages like soda, juice, coffee drinks
- Monitoring portion sizes of foods and snacks
- Choosing lower calorie options for meals and ingredients
- Increasing intake of non-starchy vegetables, fruits and lean proteins
- Tracking calories with an app to stay within daily calorie needs
Cutting out 500 calories per day from your current diet may sound challenging. But simple changes like skipping sugary drinks, decreasing portions, and filling up on veggies rather than calorie-dense foods can help decrease your daily intake without feeling too hungry or deprived.
Creating a 500 Calorie Deficit Through Exercise
You can also create a 500 calorie per day deficit through increased physical activity and exercise. Based on the calories burned estimates above, this might involve:
- Walking briskly for 60-90 minutes per day
- Jogging or running for 30-45 minutes per day
- Taking a vigorous cycling or aerobics class for 45-60 minutes
- Swimming laps for 45-60 minutes
- Weight training for 60-90 minutes per day
Any activity you enjoy and can do consistently works. The key factors are the intensity and duration. Aim for moderate to vigorous intensity and long enough duration to hit a 500 daily calorie burn. Combining cardiovascular exercise like jogging or swimming with strength training provides the best body composition improvements.
Combining Diet and Exercise for Weight Loss
For most people, the best approach combines decreased calorie intake along with increased calorie expenditure through exercise. Shoot for a 250-500 calorie daily reduction from your diet and make up the remaining deficit with activity. Not only does this create the needed 3,500 weekly deficit, it also:
- Prevents the hunger and metabolic slowdown that can come with large calorie restrictions
- Is more realistic to maintain long-term than drastic calorie cutting
- Provides health benefits and lean muscle retention from regular exercise
The best diet and exercise program for you depends on your food preferences, activity capabilities and lifestyle. But in general, aim for moderate calorie reductions, daily activity like brisk walking or jogging, and 2-3 strength workouts per week. Take a sustainable approach that you can maintain even after reaching your fat loss goal.
Factors That Impact Fat Loss
While a 500 daily calorie deficit is estimated to produce 1lb fat loss per week on average, actual results can vary based on:
Initial Body Fat Percentage
People who start with a higher percentage of body fat tend to lose fat faster than lean people, at least initially. Someone with 40% body fat will see quicker fat loss than someone with 20% body fat given the same calorie deficit. This is because the fat stores are more readily accessible for energy in an overweight person. Leaner individuals lose fat more slowly.
Genetics and Metabolic Factors
Due to genetic differences, some people tend to store and lose fat more easily than others. Fat distribution patterns also differ. Women tend to store more fat subcutaneously (under the skin), while men store more fat around the abdomen and organs. Hormones, insulin sensitivity, metabolism, and other factors can also impact fat loss results for a given diet and exercise plan.
Calorie Accounting Inaccuracies
It’s impossible to perfectly track calories from food. Food labels can be inaccurate. Calorie burn from exercise varies based on fitness, intensity, etc. So the 500 calorie deficit rule is just an estimate. Your actual results will depend on how close you come in achieving this deficit daily.
Water Weight Fluctuations
Your scale weight will decline faster than just fat loss alone due to accompanying water weight changes. During fat loss, the fat cells release stored water. Additionally, reductions in carbohydrate intake can lower water retained in the body. This water weight tends to come back once you return to normal calorie intake.
Lean Muscle Mass
The more lean muscle you have, the higher your resting metabolism will be. Resistance training while cutting calories helps maintain and even build lean muscle mass. This leads to greater fat loss over time by offsetting the drop in metabolism that can come with weight loss and aging.
Conclusion
In summary, burning about 3,500 calories more than you consume is estimated to result in 1 pound of fat loss. This equates to a daily calorie deficit of 500 calories from diet, exercise or a combination of both. Actual fat loss rates vary based on genetics, metabolic factors, accuracy of calorie measurements, water fluctuations, and lean muscle mass. For sustainable, long-term weight loss aim for moderate calorie deficits through thoughtful diet changes and regular exercise.
