We hear all the time that to lose weight you need to eat less and move more. Simple as that. Make these changes and you will lose weight. As I said in the post last week on this topic, this doesn't happen. Diets inevitably fail. I see it everyday and we have a hundred years of nutrition research to support this contention.
I equate the 'eat less, move more' advice to a business consultant telling a business owner to to simply increase revenue and cut expenses! Again, very simple, but not very helpful advice. The positive-energy balance hypothesis, also, doesn't workout so nicely. Why, because the variables (energy intake, energy expenditure, and energy storage) don't change without affecting each other. For example, decrease energy intake (low-Calorie diet) causes a decrease in spontaneous activity and increase in appetite.
So, simply dieting may cause a small decrease in energy stores. Inevitably, the changes in activity level and appetite will cause energy stores (body weight) to rebound back to it's original level. The dieting just disrupted the energy balance and over time it was corrected.
The alternative energy balance hypothesis demonstrates, what I feel, is a more accurate demonstration of causation. It can easily be supported by several biological examples. For one, a growth in a child is not caused by increased energy intake, but by elevated growth-stimulating hormone levels. The increase in growth-stimuating hormones causes not only growth, but increased energy intake and (especially in infants) increased sleep and decreased spontaneous physical activity.
When a female is pregant, energy stores increase in spite of her best efforts to limit energy intake (although total energy stores may be attenuated). Also, exercising (increased energy expenditure) may be associated by a decrease in activity at other times or increased appetite in a pregnant female. Again, energy intake, nor energy expenditure is causing the increase in energy stores (weight gain).
Finally, how does an adult, male lion, who is extremely sedentary, remain so lean? Have you ever seen an obese lion in nature (in pictures at least)? Yet, these animals eat upwards of 80 pounds of meat at a time and could easily, if he wanted to, find more food (being the king of the jungle has it's perks).
So, simply saying that Americans need to move more and eat less is really not helpful. The energy balance equation (while very easy to conceptualize) has been misinterpretted. Decreasing energy intake and increasing energy expenditure disrupts energy balance homeostasis. And, while body weight may temporarily decrease, inevitably physiological forces (that include a complex interaction of a social-psycho-neuro-hormonal regulatory system) return the individual back to their original weight.
The cause of the increase in energy stores (body fat) is not so much that we choose to overeat and move less, but our physiological regulation of energy balance is not suited for our modern environment. Energy balance, we are discovering, is so much more complicated than simply that we eat too much and move too little. Why, unlike the lion or our ancestors, does our energy regulation system fail us?