Obesity is increasingly a problem in our society. The statistics indicate that we are getting fatter as a whole, which is not healthy at either a personal level or a societal level.
Yet, we know that the question is simply one of calories. Eat more calories than you burn and the body stores the excess food as fat.
From our metabolism's point of view, no point in wasting all of that energy you've gone to the trouble to consume.
Eat fewer calories than you burn and the fat comes off.
This is the principle behind dieting. By restricting the calories in our diet and combining that with a healthy exercise program, it is possible to lose weight. Or, at least, it should be possible.
Sounds simple, doesn't it? And this is, in the words of one researcher, an "unassailable truth."
No question about it.
For many people, though, dieting doesn't seem to do the job.
Further, the fatter they get, the fatter they get. That is, being a little overweight seems to encourage the development of even more fat and a tendency to become even more overweight. It is a negative feedback loop.
Why is that?
The answer is that while the total calorie intake is important, it isn't the only component controlling our body weight. Indeed, with an obesity epidemic sweeping North America, much science is being brought to bear on the question of how and why do we gain or lose weight - at a biochemical level.
This has led to some new concepts and research in the area.
For example, the fact that fat is an endocrine tissue is now seen as important in weight control.
Endocrine tissues produce signaling agents that control other parts of the body, such as hormones.
This has led researchers to consider that the brain is the target for feeding hormones.
Fat tissue produces hormones that regulate our feeding behaviour along with the body's energy regulatory mechanism.
Both the desire to eat and the amount of heat we generate are under the control of hormones.
If this is the case, then the hormones produced by the fat cells of the body are modifying the behavioural responses of the brain which means that obesity could be viewed as a neuroendocrine disease - a disease in which the endocrine system affects the neurological processing of the brain.
That this might be the case is evidenced by the interaction of our guts and our brains.
Certainly, some of the chemicals that humans ingest have interesting effects on the mind. They can also modify the body's biochemistry.
In the mid-1970s, various scientists became increasingly interested in the mechanisms involved in the mind-body interaction. Clearly, the mind was able to interact with the body through the nervous system but they reasoned that there had to be more involved.
They were able to isolate a number of peptides that appeared to allow the body to communicate back to the brain.
The new paradigm that emerged was one in which a person's brain, gut and fat cells all communicated using these peptides.
Some researchers have even argued our fat constitutes a separate organ, which engages with other parts of the body.
And this hormonal communication is set against a backdrop of both environmental and genetic factors.
As an example, consider the peptide leptin, which is able to transport across the blood-brain barrier.
That is, it has a receptor lining the blood vessels in the brain that allow the compound to transfer from the blood vessels to neurological tissue and alter brain chemistry.
Defects in leptin production result in excessive weight gain.
Leptin acts as a control agent.
Essentially, the fat cells produce leptin, which activates its receptors in the brain - specifically, in a region of the brain called the arcuate nucleus.
This, in turn, sends signals to the body to halt feeding and increase thermogenesis or the burning of calories to generate heat.
The result is that increasing levels of fat suppress food consumption by diminishing appetite and increase energy output. Or, at least, that is what is supposed to happen.
Unfortunately, the receptor site for the leptin in the brain can become saturated. When this happens, the food consumption/exercise mechanism goes out of tilt. Increasing levels of fat do not result in a stronger signal to stop eating nor an increase in energy output. Instead, the signal gets blocked.
Although this is not the only peptide involved in food consumption, it is an example of one of the many ways that biochemical research is shedding light on the ways that our bodies work.
Understanding what is happening at the most basic levels may mean that we can change eating patterns permanently. That would mean no more dieting.
It might even mean an end to the obesity epidemic.
