This “calories per pound” rule usually does not hold up in the real world. This is because eating less or burning more calories does not come strictly from fat. Energy metabolism is complex and is influenced by many factors, including your genetic predisposition, fitness level, type of exercise chosen, present energy stores, and your motivation.

Muscle cells need oxygen and fuel to work. The fuel your body chooses can come from different sources, depending on several factors. Fat is not necessarily the best source of fuel for muscle cell energy. Muscle cells need a constant supply of oxygen in order to burn fat continuously. If you are sedentary and not in shape you cannot supply this constant supply of oxygen and the body uses a fuel sources other then fat. Carbohydrates are an alternative quick burning fuel that requires no oxygen.

The result is carbohydrates and fats are BOTH used to supply the cell’s energy. The proportion of carbohydrate to fat used depends on factors such as the individual fitness level and the type/intensity of exercise performed. We therefore need more then 3600 calories to burn off a pound of fat.

Low carbohydrate diets can help some people lose weight. However, most of the loss will not all be fat especially in the initial stages when weight loss is rapid. Remember that your body does not use only fat for energy because burning fat requires a sufficient supply of oxygen. Overweight people tend to have lower fitness levels than lean people thus their bodies cannot always keep up with oxygen demands required when exercising. This is why an exercise regimine will become easier as your body becomes more fit.

Besides burning fat and carbohydrates for energy, our body can also burn protein for energy metabolism. If carbohydrates are limited, the body simply burns more protein by converting it to carbs in the liver, a process known as Gluconeogenesis. Gluconeogenesis actually goes on all the time but if carbohydrates are restricted the process is accelerated especially during exercise. As we have an abundance of protein in the body simply cutting carbohydrates won’t transform the body into a lean fat-free machine.

To sum up, your body always burns a combination of fats, carbohydrates and protein and there is more reliance on the latter two fuels when movements demand more effort and therefore oxygen. To burn off enough calories per pound of fat we need to take into account the number of calories that come from carbohydrates and protein!