A calorie deficit is the "magic" that makes weight loss possible. It forces the body to use fat stores for energy causing weight loss. While a calorie deficit is the only way to lose weight, there are a few ways to create one, though they all involve improving eating and exercise habits.
What is a calorie deficit?
A calorie deficit is a state in which you burn more calories than you consume. For example, if you burn 2,500 calories per day but only eat 2,000, you have created a deficit of 500 calories per day. A calorie deficit forces the body to use non-food sources of energy (typically body fat though the body can also burn muscle tissue for energy) to make up for the shortfall causing weight loss.
How to Lose Weight
Creating a calorie deficit is the only requirement for weight loss. The first step is figuring out how many calories your body burns each day. The calorie calculator is a good place to start. It estimates calorie needs based on size, gender and physical activity level.
The next step is to track your calorie intake and ensure you eat 500-1,000 calories less than you burn each day. For example, if the calculator estimates you burn 3,000 calories per day, eating 2,000-2,500 calories creates a deficit of 500-1,000 calories per day. This energy deficit or shortfall (500-1,000 calories per day) causes weight loss. MyFitnessPal is a popular, free and easy to use smartphone app for monitoring calorie intake and body weight.
It's important to remember the calorie calculator only provides an estimate. While the calculator is good at giving the average person a good starting point, it is very possible the estimate is not accurate for you. The only way to gauge the accuracy of the estimate is to carefully track both body weight and calorie intake. Adjust calorie intake accordingly based on the week to week change in body weight (eat less if your weight is going up, eat more if it's going down too quickly).
How to Lose Body Fat
Burning body fat and losing weight are two ways of describing the same process. A calorie deficit forces the body to burn fat causing weight loss. A calorie deficit simultaneously decreases body fat percentage and causes weight loss.
The body stores fat in response to a calorie surplus (eating more than you burn). Genetics determine where fat is stored. For some, the body stores fat predominantly in the arms, and for others, around the midsection.
During a calorie deficient state, the process is reversed. Genetics also determine which areas the body burns fat from. Though you may want to get rid of flabby arms or a large midsection, the process is exactly the same because there is no way to influence where the body burns fat from.
Targeting the midsection with sit-ups or the arms with curls does not force your body to burn fat from those areas; spot reducing is impossible. A calorie deficit is the only way to lose weight and burn fat.
Ways to Create a Calorie Deficit
There are a few ways to create a calorie deficit: eat less, move more or combining both approaches. Though it's possible to lose weight with diet or exercise alone, the fastest, healthiest and longest lasting results only happen when you combine a moderate restriction in calorie intake with more exercise.
Dieting simply requires you eat less. This is a great opportunity to eliminate unhealthy foods such as empty calories. Empty calories are foods are high in energy (calories) but low in nutrients (vitamins, minerals, antioxidants, fiber): candy, soda, cookies, muffins, potato chips and most junk/fast foods. Instead, fill your diet with nutrient dense foods which are low in calories but very high in nutrients: 100% whole wheat products (bread and pasta), brown rice, fruits and vegetables.
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Physical activity increases the size of a calorie deficit without sacrificing food. Incorporate cardiovascular exercise into your routine 3-5 times per week, 30-60 minutes per session. Strength training is also a great way to burn calories and vary a workout routine. Incorporate strength training into your routine 3-4 times per week.
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There are an endless amount of shortcuts (i.e. diet pills, weight loss programs, books, exercise routines) claiming you can lose weight with minimal effort. There are no shortcuts! Creating a calorie deficit (through moderate calorie restriction and increase in physical activity) is the only way to lose weight. Any plan that does not require sacrifice is unrealistic and leads to failure.
The Bottom Line
Losing weight requires you to make difficult changes to everyday habits. Avoid making these changes too quickly. Slowly build up a calorie deficit by moderately cutting intake and increasing physical activity. Slow changes are much more likely to stick than abrupt ones that happen overnight. Slow change is the key to losing weight, keeping it off and improving overall health.