Losing Fat – Why is it so difficult?

“Fat is an amazing tissue. It has ensured survival of our species through two ice ages and never ending drought and famine. A mere pound of fat stores an astounding 3500 calories for delayed use at any time in the future.” Doug McGuff, M.D.  It seems now that an adaptation that has allowed us to survive through history is now killing us in modern times.

Most people believe that the reason modern man is becoming more obese is the labor saving technologies have made humans more sedentary, and we are much less physically active than our predecessors. This argument seems logical, but the argument is incorrect for two basic reasons.

First, physical activity burns much less calories than we were led to believe. An hour of jogging will burn about 150 calories above our BMR (Basil Metabolic Rate), which is the lowest rate of body metabolism that can sustain life. However, it only takes about 30 seconds to consume 150 calories worth of cookies. Doing enough exercise too utilize a significant number of calories puts the body at greater risk to overuse injuries. Just like anything else in life, exercise is beneficial up to a point. After that point, it becomes counterproductive.

Secondly, our ancestors were not as physically active as we think they were. The work of anthropologists who observe primitive peoples in various regions of the globe show that a primitive hunter/gatherer life style is much less physically active than that of modern man. The real problem with obesity is food abundance. Not since after the Great Depression and WWII has starvation not been a real problem. We have 150,000 generations where efficient fat storage was essential for survival, and 3-4 generations where efficient fat storage can lead to obesity. Over thousands of years of evolution our bodies have become extremely efficient at storing calories for energy, but that makes it extremely difficult for us to loose body fat through energy expenditure.

The moral of the story is that if you want to lose body fat, physiologically speaking, it’s a lot safer and easier to lose it by consuming less calories than from exercise.