There's a common misconception of what the phrases, "losing weight", "burning fat" and "increasing muscle tone" mean. While many treat these three phrases as separate goals, the truth is that they're different ways of saying the same thing. Weight loss is a reduction in body fat; burning fat causes a decrease in body weight and increase in muscle tone. Regardless of what you want to call it, the same steps lead to weight loss, decreased body fat and increased muscle tone.
Excess body fat is the enemy. It causes an unsightly physical appearance and a wide range of health issues ranging from heart disease to cancer. Excess body fat is the consequence of eating too much and/or exercising too little. The solution is simple: expend more energy and/or consume less calories (combining both works best).
A calorie deficit is the "magic" behind weight loss (or fat burning if you prefer). A calorie deficit is a state in which you burn more calories than you consume. A calorie surplus is the opposite of a deficit: a state in which you consume more than you burn. During a calorie surplus, the body is forced to deal with extra energy (the difference between how much you eat and burn).
If you consume 3,000 calories but only burn 2,000, the body has to do something with the extra 1,000 calories (3,000 - 2,000 = 1,000 calorie surplus of energy). Energy doesn't simply disappear; it's either used or stored. Without adequate amounts of physical activity, the body stores an energy surplus as fat leading to weight gain.
Ways to Lose Weight/Burn Fat/Increase Tone
A calorie surplus is the cause of unwanted body fat/weight gain. The opposite of a surplus (calorie deficit)is the solution. A calorie deficit forces the body to use non-food sources of energy, in other words, body fat.
If you consume 2,000 calories in a day but burn 3,000, those extra 1,000 calories must come from something other than food. A calorie deficit causes weight loss, body fat reductions and an increase in muscle tone.
The calorie deficit equation has two variables (calories consumed and calories burned) meaning there are multiple ways to create one. The first is decreasing calorie intake. When you eat less, the body is forced to look for non-food sources of energy (body fat). The second way is burning more calories. When you increase energy expenditure beyond what you provide in food, the body is again forced to look to body fat to make up the difference.
Do I have to eat less to burn fat?
The only requirement of burning fat or losing weight is a calorie deficit. A calorie deficit simply means you're burning more than you're consuming. You don't necessarily have to eat less, though doing so makes it all much easier.
To create a calorie deficit without eating less, you'd simply have to burn more calories. As long as you burn more than you consume, you'll lose weight/burn fat. Eating less however, makes creating a calorie deficit much easier.
If you were to take a combined approach (eating less AND exercising more), you could create a deficit of 700 calories by:
- burning 350 more calories each day ~ 3.5 mile run
- consuming 350 less calories each day
- total: (350 more calories burned) + (350 less calories consumed) = 700 calorie deficit
Creating a deficit of 700 calories through exercise alone is possible:
- burning 700 more calories each day ~ 7 mile run
- consuming the same
- total: (700 more calories burned) + (0 less calories consumed) = 700 calorie deficit
The result of each scenario is a deficit of 700 calories. In the combined approach, approximately 3.5 miles of running was enough. In the exercise-only approach, the same size deficit requires a 7 mile run. This sort of physical activity is out of reach for many people.
The Bottom Line
While it's mathematically possible to burn fat without eating less, an exercise-only strategy isn't the best way to accomplish your fitness goals. Eating less, combined with exercising more, makes burning fat/losing weight/increasing muscle tone a lot easier.