The major determinant of body weight is the amount of food we eat. This itself is a balance between the natural drive to replace used nutrients (hunger) and the signals from our gastrointestinal tract that report we have eaten adequately, and which switch off the process of eating to allow efficient digestion of our ingested food (satiety).
Hunger and satiety are opposing drives that are regulated by our brain in order to control the amount of food we eat.
We have evolved powerful brain circuitry to protect our body weight in situations where food is unavailable, for example, starvation. Therefore, we tend to increase our drive to eat while, at the same time reducing, where possible, the amount of energy we expend.
Unfortunately, such counter regulation also occurs when we diet or exercise. We tend to want to eat and to become more sedentary afterwards, making it difficult to lose weight voluntarily.
Understanding our natural regulatory systems
When we eat, our brain receives signals from the gastrointestinal tract to aid digestion and reduce further intake, partly through inducing the feeling of fullness. However, even in this state of satiety, the regulatory pathways can be overcome if we are given the choice to eat a very palatable food (our stomach always seems to find space for pudding!)
The pressures on natural regulatory systems are also extensive in our modern society. For example, we might work or play at night when we should be sleeping.
Researchers at Manchester use a combination of experimental techniques and phenotyping tools in order to understand how the brain regulates energy intake and energy expenditure.
This involves using a state-of- the-art toolkit, including transgenic mice and gene recombination techniques. This allows us to map, record and manipulate specific types of brain cell in vitro, and in freely behaving animals.
This is then coupled with a suite of physiological and behavioural phenotyping technologies, allowing us to record eating and drinking, locomotor activity and energy expenditure.