Activity

• Activity levels influence the rate of fat oxidation. Fat and oxygen are used in conjunction to produce energy, so any type of exercise increases the rate of fat oxidation. An idle lifestyle, on the other hand, will decrease it. Studies by "Medicine & Science in Sports & Exercise" show that lower intensity exercise, such as jogging or steady cycling, burns mainly fat for energy during exercise. Intense exercise, on the other hand, such as circuit training, burns predominantly carbohydrates for fuel. Intense exercise, however, has been shown to increase metabolic rate overall, thus increasing the rate of fat oxidation even during periods of rest.
  
  

Foods

• Diet and nutrition are contributing factors to the rate of fat oxidation. Some foods naturally increase the metabolic rate and therefore the rate of fat oxidation. These foods include grapefruit, broccoli, lean turkey, oatmeal, hot peppers, apples and pears. Foods low in sugar or carbohydrates generally increase the rate of fat oxidation. Most protein sources such as meat, whey supplements and eggs also increase fat oxidation.
  
  

Fat Oxidation Inhibitors

• Foods that inhibit fat oxidation include sugar, fried foods, white bread, most processed foods and alcohol. This reduction in fat oxidation is caused by a sudden spike in insulin levels. High insulin levels encourage the body to utilize the excess carbohydrates as fuel, thus decreasing fat oxidation. Foods high in saturated fats, such as fried foods, increase cholesterol and slow the rate of fat oxidation. A diet high in carbohydrates slows fat oxidation as high levels of glycogen stored in the muscles fuel the body.
  
  

Metabolic Rate and Thyroid

• The thyroid gland determines the body's resting metabolic rate. An under-active thyroid gland will result in a slow rate of fat oxidation and an overactive thyroid gland will result in a fast rate of fat oxidation. The efficiency of the thyroid gland can be determined by genetics or environmental factors such as lack of food. The "American Journal of Clinical Nutrition" concluded that lack of proper nutrition impaired the body's ability to oxidize fat properly.
  
  

Caffeine

• Caffeine products have been shown to increase the rate of fat oxidation and resting metabolic rate. Coffee, caffeine pills, black tea, oolong tea and green tea have been shown to increase the metabolic rate by up to 12 percent.