To become fit most people go on a diet. What they really want to achieve is fat loss. Then the question becomes - how do I burn body fat?

Isn't that the 64 thousand dollar question?

If the body feels threatened then it will store energy as fat as a reserve against that threat. Much of this protective activity by the body is involuntary, meaning that we might be afraid of the dark, but that is not likely to cause our body to store energy.
However, if we are starving ourselves trying to lose weight, the body will react and actual start to store fat against the contingency of starvation. Your body will literally be fighting your efforts to lose weight.

Back to how to convince the body to burn body fat and not store fat as an energy reserve.

We all have eating and activity routines. We establish a pattern, a history from which our body will attempt to predict our future energy needs. It will store energy to offset future demands. If the body perceives no future shortfalls in the energy supply, then it will see no need to store energy.

The 'Calorie Shifting' weight loss strategy attacks the predictability of our eating patterns. It addresses the total amount of calories required together with the types of calories. The net result is that this strategy confuses the body so that it cannot see a pattern from which to predict future requirements. With no future demands predicted, there is no need for fat storage.

Proteins and carbohydrates are sources of energy. When the body burns the sources of energy different hormonal reactions occur. Calorie shifting manipulates the natural responses of the body. The body then burns fat which is our goal.

Carbohydrates which are densely caloric are minimized within the calorie shifting diet. This leaves fats, proteins and low glycemic carbs. The body will burn primarily fats and carbs to produce energy for our daily requirements.

A quick tangent here, more numbers in later posts: the losses associated with each type of energy source are: 3% for fat and 25% for carbohydrates and 25% for proteins. The human body is a very efficient machine. When given the choice between a 3% loss and a 25% loss, it will choose the 3% loss if there are no overriding additional factors.

Back to burning fat to meet energy requirements. With calorie shifting, we are giving the body several energy choices: body fat, food fat, food protein and food carbohydrate. Unless it feels threatened and decides to store energy as fat, it will burn the fats before the carbs and protein to maximize conversion efficiency.

When the body burns our body fat to produce our daily energy, then body fat is reduced and we accomplish our goal of weight loss.

1 gram of fat contains 9 calories
1 gram of carbohydrate contains 4 calories
1 gram of protein contains 4 calories

Energy expended by the body to convert to energy:
3% of fat calories are burned to convert to energy or storage.
25% of carbohydrate calories are burned during conversion.
25% of protein calories are burned during conversion.

Here are my statistics
Male
60 years old
190 pounds
5 foot 10 inches tall
Basal metabolic rate = 1727 calories
Activity Levels
Inactive = 2100 calories
Somewhat Active = 2300 calories
Active = 2500 calories
Very Active = 2900 calories

Take note of the basal metabolic rate in comparison to the active rate. The difference is only 773 calories.
If we assumed that those calories were all fat as our energy source, then that's about 86 grams or .2 pounds or 3 ounces of fat.
If we assumed that those calories were all proteins or carbohydrates as our energy source, then that's about 193 grams or .42 pounds or 6.8 ounces of either carbs or protein.

Here are some conversions tables for the metric impaired.
grams to pounds
grams to ounces"

Here are the energy demands in grams and ounces for either energy source (fat or carb/protein) for several metabolic levels. I have continued to use myself as the guinea pig.

Basal metabolic rate: 1727 calories which is 192 gm or 6.7 ounces of fat. Alternatively that is 432 gm or 15.1 ounces of carbs or protein.

Basal metabolic rate: 1727 calories which is 192 gm or 6.7 ounces of fat. Alternatively that is 432 gm or 15.1 ounces of carbs or protein.

Inactive metabolic rate: 2100 calories which is 233 gm or 8.2 ounces of fat. Alternatively that is 525 gm or 18.4 ounces of carbs or protein.

Somewhat active metabolic rate: 2300 calories which is 256 gm or 9 ounces of fat. Alternatively that is 575 gm or 20.1 ounces of carbs or protein.

Active metabolic rate: 2500 calories which is 278 gm or 9.7 ounces of fat. Alternatively that is 625 gm or 21.9 ounces of carbs or protein.

Very active metabolic rate: 2900 calories which is 322 gm or 11.3 ounces of fat. Alternatively that is 725 gm or 25.4 ounces of carbs or protein.

The point of all these numbers is to demonstrate that there is not a lot of difference between the basal metabolic rate and a metabolic rate associated with a reasonable level of activity.
Accordingly, depending on exercise alone to lose weight might present a significant challenge. Do not misunderstand me on this point. Exercise is a cornerstone to good health. It is also an ally of fat loss programs.
But it is more important to shift calories and to ensure that the proper calories are being burned.
If fat loss is your goal, you would be much wiser to walk for 30 minutes twice a day, then jog, or run or do strenuous aerobic exercises.
As the body senses more stress and strain it shifts its burn source from fat to carbohydrates.
To lose fat - we want to burn fat.
The body burns fat during light exercise.