How Long Does It Take for Excess Calories to Turn to Body Fat?

Illnesses related to obesity cause nearly 300,000 deaths per year in the United States, which makes obesity second only to smoking as the leading cause of preventable death. Due to the health risks associated with excessive body fat, it is vital to understand how the body gains weight and the amount of calories it takes for the body to begin storing this energy as fat accumulation.

One pound of body fat consists of a total of 4,086 calories, but within each fat cell are water, minerals and protein, as well as fat. Thus, the actual caloric amount within 1 lb. of body fat is 3,500 calories.

Once food is consumed, your body either uses calories as energy to fuel your body, or stores these calories in fat cells to be called upon at a later time. Dr. David Katz, reports in "O, the Oprah Magazine," that the body begins to store consumed calories as fat within four to eight hours from the beginning of the meal. As you consume these calories, the body automatically stores the first 1,000 calories within the liver and muscles for immediate energy reserves. This calorie storage is known as glycogen. Once the glycogen calories are utilized for energy, the body then activates stored calories within fat cells, known as triglycerides, to replenish the depletion of glycogen calories.

Aerobic activity enhances the body's ability to deplete stored fat cells through enhanced oxygen delivery throughout the body and increased release of fatty acids into muscle tissue, which results in fat stores being more readily available to be burned. Aerobic activities are defined by the Georgia State University Department of Kinesiology and Health as any activity that actively engages muscle groups and causes an increase in heart rate and breathing. Examples of aerobic activities include jogging, jumping rope, swimming, stair-climbing and bicycling. The American Heart Association suggests healthy adults should perform a minimum of 150 minutes of moderately-intense aerobic exercise per week, with a single exercise session lasting at least 10 minutes.

Along with aerobic exercises, strength training is vital to maintain calorie burning. Website Shape Fit says each pound of muscle burns 30 to 50 calories per day just to sustain itself. Thus, the more muscle mass your body contains, the more calories your body automatically burns. The American College of Sports Medicine suggests performing strength training exercises, which challenge specific muscle groups, such as pushups or bench presses, at least two times per week on nonconsecutive days.